Section 1 The Circulatory System - · PDF filethe circulatory system, and write them on the board. ... 872 Chapter 38 • Circulatory and Respiratory Systems Transparencies TT Bellringer

OverviewBefore beginning this sectionreview with your students theobjectives listed in the StudentEdition. Students will be able todescribe the structure of the heartand blood vessels (cardiovascularsystem), how these structures func-tion in transporting materials allaround the body, and how materi-als move into and out of the bloodvessels. Students will also describethe structure of the lymphatic sys-tem, how it picks up excess fluidsin body tissues and returns them tothe cardiovascular, and the role ofthe lymphatic system in immunity.

Ask students the following ques-tion: Is blood a liquid or a solid?Then, have them write down whatthey think is found in blood. (Manystudents will know that plasma(liquid) and blood cells (solid) are in blood. Blood also contains water,hormones, antibodies, nutrients,oxygen, carbon dioxide, salts, ions,wastes, and other materials.)

ActivityCirculatory Function Ask stu-dents to name possible functions ofthe circulatory system, and writethem on the board. (The circulatorysystem carries oxygen, carbon diox-ide, nutrients, hormones, cells of theimmune system, wastes, and othermaterials; and it is involved in regu-lating body temperature.) VerbalTAKS 2 Bio 10A

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Section 1

872 Chapter 38 • Circulatory and Respiratory Systems

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TT BellringerTT Cardiovascular SystemTT Blood Vessels

• Lesson Plan• Directed Reading• Active Reading• Data Sheet for Quick Lab GENERAL

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Chapter Resource File• Reading Organizers• Reading Strategies • Occupational Application Worksheet

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Section 1 The Circulatory System

Transport and Distribution Regardless of your activities—whether you are roller-blading,swimming, singing, reading, or just sleeping—your body transportsnutrients, hormones, and gases, and it gets rid of wastes. Two bodysystems play major roles in these functions. The circulatory system,which includes the cardiovascular and lymphatic systems, trans-ports these materials to different parts of the body. The respiratorysystem exchanges gases with the environment—it takes in oxygen,O2, and releases carbon dioxide, CO2.

The human , shown in Figure 1, functionslike a network of highways. The cardiovascular system connects themuscles and organs of the body through an extensive system of vessels that transport blood, a mixture of specialized cells and fluid.The heart, a muscular pump, propels blood through the blood vessels.

Different kinds of molecules move through the cardiovascularsystem:

1. Nutrients from digested food are transported to all cells in thebody through the blood vessels of the cardiovascular system.

2. Oxygen from the lungs, where the oxygen is taken in, is trans-ported to all cells through blood vessels.

3. Metabolic wastes, such as carbondioxide, are transported throughblood vessels to the organs andtissues that excrete them.

4. Hormones, substances whichhelp coordinate many activitiesof the body, are transportedthrough blood vessels.

5. The cardiovascular system alsodistributes heat more or lessevenly in order to maintain aconstant body temperature. Forexample, in a warm environ-ment, blood vessels in the skinrelax to allow more heat to leavethe body. In a cold environment,blood vessels constrict, conserv-ing heat by diverting blood todeeper tissues. This diversion ofblood prevents heat from escap-ing the body.

cardiovascular system

Objectives● List five types of molecules

that are transported by thecardiovascular system.

● Differentiate between arteries, capillaries, and veins.

● Relate the function of thelymphatic system to the func-tions of the cardiovascularand immune systems.

● Relate each component ofblood to its function.

● Summarize how a person’sblood type is determined.

Key Terms

cardiovascular systemarterycapillaryveinvalve lymphatic systemplasmared blood cellanemiawhite blood cellplateletABO blood group systemRh factor

Figure 1 Blood vessels,blood, and a heart.The cardiovascular systemtransports materialsthroughout the body anddistributes heat.

Cardiovascular System

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Student Edition TAKS Obj 2 Bio 4B TAKS Obj 2 Bio 10A TAKS Obj 2 Bio 10B TEKS Bio 4B, 9A, 10A, 10B

Teacher Edition TAKS Obj 3 Bio 4C TAKS Obj 2 Bio 10A TEKS Bio 4C, 5C, 9A, 10A, 11C

pp. 872–873

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Teaching TipBlood-Brain Barrier Providestudents with the information con-tained in the Medicine Connectionfeature at the bottom of this page.Point out that, while the exclusionof most chemicals from the brain isadvantageous, it can be a seriousproblem when physicians try totreat disorders involving the brainand brain function. A major diffi-culty in treating brain tumors, forexample, is that most of the chemi-cal agents used to treat cancer cannot reach targets across theblood-brain barrier. The blood-brain barrier also prevents most ofthe anti-retroviral drugs now usedto treat AIDS from entering thecentral nervous system. In additionto infecting cells of the immune system, HIV directly infects cellswithin the brain itself and theblood-brain barrier prevents thesedrugs from battling HIV-infectedcells in the brain.

Using the Figure Direct students’ attention toFigure 2. Point out that veins havea much wider inside diameter thanarteries. This difference relates tothe differences in function of thesetwo kinds of vessels. Arteries trans-port blood away from the heartunder high pressure and force itinto tiny capillaries. Veins transportblood rapidly and under low pres-sure back to the heart. Point outthe thicker muscular wall of theartery in the figure. Also point outthe valve located in the vein.

Interactive Reading AssignChapter 38 of the Holt BiologyGuided Audio CD Program to helpstudents achieve greater success inreading the chapter.

SKILLBUILDER

READINGREADING

TAKS 2 Bio 10A

TAKS 3 Bio 4C; Bio 5C, 11C

GENERAL

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Chapter 38 • Circulatory and Respiratory Systems 873

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actively transported into the fluid surround-ing the brain cells. This barrier’s most important function is toprovide neurons with the exact amount of glu-cose they need. If glucose levels go up or downeven slightly, neurons can begin to malfunction.The blood-brain barrier also maintains a precisebalance of necessary ions within the brain. Theconnections between neurons are sensitive toion concentrations, and even minor changescan affect nerve transmission. Bio 5C, 9A, 11C

The blood-brain barrier is made up of a sin-gle layer of endothelial cells that are tightlypacked together and line the inner surfaces ofcapillaries in the brain. Endothelial cells inother parts of the body have gaps betweenthem through which water, ions, molecules,and even some blood cells can easily diffuse.Water is the only constituent of the bloodthat can diffuse freely across the blood-brainbarrier. Substances required by the brain,such as glucose and other nutrients, are

Venule (connects veins

to capillaries)

Arteriole(connects arteries

to capillaries) Connective tissue

Smooth muscle

Endothelium

Valve

Capillaries(exchange gases, nutrients,

wastes, and hormones)

Vein(returns blood to the heart)

Artery(carries blood away from the heart)

Blood VesselsBlood circulates through the body through a network of vessels.

(AHRT uh reez), shown in Figure 2, are blood vessels thatcarry blood away from the heart. Blood passes from the arteriesinto a network of smaller arteries called arterioles (ahr TIHR eeohls). Eventually, blood is pushed through to the capillaries.

are tiny blood vessels that allow the exchange ofgases, nutrients, hormones, and other molecules in the blood. Themolecules are exchanged with the cells of the body. From the capil-laries, the blood flows into small vessels called venules (VEHNyools). From the venules, blood empties into larger vessels calledveins (vaynz). are blood vessels that carry the blood back tothe heart.

Arteries With each contraction, the heart forcefully ejects blood into arteries.To accommodate each forceful pulse of blood, an artery’s wallexpands and then returns to its original size. Elastic fibers in thewalls of arteries allow arteries to expand.

The wall of an artery is made up of three layers of tissue, asshown in Figure 2. The innermost layer is a thin layer of epithelialtissue called the endothelium. The endothelium is made up of a single layer of cells. Surrounding the endothelium is a layer ofsmooth muscle tissue with elastic fibers. Finally, a protective layerof connective tissue with elastic fibers wraps around the smoothmuscle tissue. Just as a balloon expands when you blow more airinto it, the elastic artery expands when blood is pumped into it.

Veins

Capillaries

ArteriesReviewing Information You can remember thatarteries take blood awayfrom the heart and veinscarry blood toward the heartby remembering the letter aat the beginning of the wordartery and at the beginningof the word away.

Magnification: 1,150�

Blood vessels transport blood and allow for the exchange of substances.

Figure 2 Blood vessels

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DemonstrationShow the class a picture of a personin a hospital bed. Ask why hospitalworkers try to get patients to walk,if only for a few minutes each day.(Students should recognize that musclemovements squeeze the walls of veins,thus preventing blood from accumu-lating and clotting in parts of the bodysuch as the legs. Other methods ofenhancing circulation used in hospitalsinclude special compression hoses andpumps that promote blood flowthrough the lower extremities.) Askstudents what happens to them ifthey stand in one place for a longperiod of time, as during a schoolassembly or concert. (Most will haveexperience some discomfort and possi-bly dizziness if they have stood for along time.) Tell students that they canhelp move blood back to the heartwhile standing if they repeatedlybend their legs at the knees.TAKS 2 Bio 10A, 10B

Teach, continuedTeach, continued


Answer

Student answers will vary, butshould indicate that in generalexercise increases circulation.

Bio 11C

Real Life

Capillaries No cell in your body is more than a few cell diameters away from acapillary. At any moment, about 5 percent of your blood is in capil-laries. In capillaries, gases, nutrients, hormones and other mol-ecules are transferred from the blood to the body’s cells. Carbondioxide and other wastes are transferred from the body’s cells to thecapillaries.

The extensive back-and-forth traffic in the capillaries is possiblebecause of two key properties. Capillary walls are only one cellthick, so gas and nutrient molecules easily pass through their thinwalls. Capillaries are also very narrow, with an internal diameter ofabout 8 µm (0.0003 in.)—a diameter only slightly larger than thediameter of a red blood cell. Thus, blood cells passing through a cap-illary slide along the capillary’s inner wall, as shown in the photo inFigure 2. This tight fit makes it easy for oxygen and carbon dioxideto diffuse to and from red blood cells through the capillaries.

VeinsThe walls of veins consist of a much thinner layer of smooth muscle,than the walls of arteries. They are farther from the heart pump andexposed to lower pressures. Veins do not receive the pulsing pres-sure that arteries do.

As shown in Figure 2, veins also differ from arteries in that they are larger in diameter. A large blood vessel offers less resis-tance to blood flow than a narrower one, so the blood can movemore quickly through large veins. The largest veins in the humanbody are about 3 cm in diameter—about the same diameter asyour thumb.

Most veins have one-way valves. A is a flap of tissue thatensures that the blood or fluid that passes through does not flowback. Valves in veins, such as the one shown in Figure 3, prevent theblood from flowing backward during its trip to the heart. When theskeletal muscles in your arms and legs contract, they squeezeagainst the veins, causing the valves to open and thus, allowing the

blood to flow through. When the skeletal muscles relax,the valves close, preventing the backflow of blood.

Sometimes the valves in the veins become weak and theveins become dilated (larger in diameter). Veins that aredilated because of weakened valves are called varicoseveins. Dilated veins that occur in the anal area are calledhemorrhoids.

Lymphatic SystemBecause the blood plasma is rich in proteins, most of thefluid remains in the capillaries due to osmotic pressure.However, every time the heart pumps, some fluids areforced out of the thin walls of the capillaries. The fluidthat does not return to the capillaries collects in spacesaround the body’s cells. The fluid that collects around the

valve

Magnification: 122�

Figure 3 Valves in veins.Valves are most abundant in the veins of the arms and legs, where the upwardflow of blood is opposed by gravity.

Real LifeHow long are all of yourcapillaries? If all of the capillaries ofyour body were laid end toend, they would extend allthe way across the UnitedStates! The network ofcapillaries in the body is several thousand miles long. Finding InformationFind out how capillariesrespond to long-termaerobic training. 11C

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Student Edition TAKS Obj 1 Bio/IPC 2B, 2C TAKS Obj 2 Bio 4B TAKS Obj 2 Bio 10A TAKS Obj 2 Bio 10B TEKS Bio 4B, 10A, 10B, 11CTEKS Bio/IPC 2B, 2C

Teacher Edition TAKS Obj 1 Bio/IPC 2B, 2C TAKS Obj 2 Bio 4B, 10A, 10B TAKS Obj 5 IPC 4A, 4B TAKS Obj 5 IPC 6B TEKS Bio 4B, 5A, 10A, 10B, 11CTEKS Bio/IPC 2B, 2CTEKS IPC 6B

pp. 874–875 IPC Benchmark Fact

Remind students that as the circulatory system distrib-utes heat throughout the body, energy transfers fromthe particles of one object to the particles of anotherobject because of their different temperatures. Whenthe energy transfer or heat flows, it moves from thehotter object to the cooler object. TAKS 5 IPC 6B

IPC Benchmark Mini-Lesson

IPC Skills TAKS 5 IPC 4A, 4BCalculate speed in systems such as the human body.Investigate applications of Newton's laws.Activity Tell students that there is an inverse rela-tionship between pressure and flow rate. The faster a fluid flows through a tube, the lower the pressurethe fluid exerts on the walls of the tube. Blood flowsfaster through capillaries than it does through arter-ies. Using this information have students explain whycapillary walls can withstand the pressure resultingfrom blood flowing through them.

Teaching TipStability and Homeostasis Pointout to students that swollen lymphnodes contain large numbers ofimmune system cells (white bloodcells) that are actively engulfingbacteria or virus particles. For thisreason, the nodes become inflamedand tender when the body is fight-ing an infection.

Using the FigureDirect students’ attention toFigure 4. Have them examine thevessels and lymph nodes, includingthe tonsils and spleen. Ask them toidentify some ways in which thelymphatic system is different fromthe cardiovascular system. (Thelymphatic system does not run in acircuit, as the cardiovascular systemdoes. The lymphatic system alsodoes not have its own pump, like theheart of the cardiovascular system.)TAKS 2 Bio 10A

GENERAL

TAKS 2 Bio 4B


Mapping theValves in VeinsSkills AcquiredInferring relationships,identifying functions

Teacher’s NotesInstruct students to allow theirarms and hands to hang in a relaxed manner for 1 to 2minutes before beginning theexperiment. This demonstrationwill also work on the veins inthe back of the hand.

The effect will be more pro-nounced if the blood issqueezed out of the veinbetween the first and secondfinger. Have students do this bygently stroking the vein towardthe heart.

Answers to Analysis1. toward the elbow, and so

toward the heart2. Blood will have to go against

gravity, enlarging the veinslightly.

3. Blood will pool in the veins inthe legs.

travel through the bloodstream or lymphaticsystem to other parts of the body. Cancer cellsmay spread to lymph nodes near the primarytumor. Cancer cells can also spread to otherparts of the body, distant from the primarytumor. Doctors use the term metastatic diseaseor distant disease to describe cancer that spreadsto other organs or to lymph nodes other thanthose near the primary tumor. When cancer cellsspread and form a new tumor, the new tumor iscalled a secondary, or metastatic, tumor.TAKS 2 Bio 4B; Bio 5A

Cancer is a group of related diseases thatoccur when cells keep dividing but new cellsare not needed. These extra cells may form amass of tissue, called a tumor. Tumors can beeither benign (not cancerous) or malignant(cancerous). Cancer can begin in any organ ortissue of the body. The original tumor is calledthe primary tumor and is usually named forthe part of the body where it begins.Metastasis means the spread of cancer. Cancercells can break away from a primary tumor and

REAL WORLDREAL WORLDCONNECTIONCONNECTION

cells is picked up by the lymphatic system andreturned to the blood supply.

The collects and recycles fluidsleaked from the cardiovascular system and is involvedin fighting infections. As shown in Figure 4, the lymphatic system is made up of a network of vesselscalled lymphatic vessels and tiny bean-shaped struc-tures called lymph nodes. Lymph tissue is also locatedin various places throughout the body, including the thymus, tonsils, spleen, and bone marrow.

Lymphatic vessels carry the leaked fluid, calledlymph, back to two major veins in the neck. Similar toveins, lymphatic vessels contain valves that prevent thebackflow of the fluid. The fluid is pushed through the lymphatic vessels when the skeletal muscles in thearms and legs contract.

The lymphatic system also acts as a key element inthe immune system. Immune cells in the lymph nodesand lymphatic organs help defend the body againstbacteria, viruses, other infecting microbes, and can-cerous cells. Lymph nodes, which are concentrated inthe armpits, neck, and groin, sometimes get tenderand swell when they are actively fighting infectionand filled with white blood cells. Health-care pro-fessionals are trained to detect certain types of infections by feeling for the lymph node swellings onthe body.

lymphatic system

Mapping the Valves in VeinsBy applying pressure to your arm, you can locate the valves in the veins of your arm.

Materials

nontoxic felt-tip pen

Procedure

1. Have a classmate make a fistand extend his or her arm,with the hand palm up andslightly below elbow level.Locate a prominent vein onthe inside of the forearm.Using one finger, press downon the vein at a point near thewrist to block the blood flow.

2. Gently place a second fingeralong the vein about 5 cmfrom the first finger (toward theelbow). Release the secondfinger, but not the first. Thevein should refill partway. Markthis point, which indicates thelocation of a valve, with a pen.You may have to try more thanone vein to locate a valve.

Analysis

1. Identify the direction bloodflows in the vein you chose.

2. Propose why the subjectmust make a fist and hold hisor her arm slightly down.

3. Infer what effect standing inone place for long periods oftime might have on the veinsin the legs.

Lymphatic System

Thymus

Lymph node

Spleen

Lymphatic vessel

Bone marrow

Tonsils

Figure 4 Lymphatic tissues. Lymphatic tissues are located throughout the body.

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TAKS 1 Bio/IPC 2B, 2C; TAKS 2 Bio 10A

TAKS 1 TAKS 2

Math Skills A human adult hasabout 5 L (1.25 gal) of blood.Plasma is more than 90 percentwater. The body contains some 30trillion red blood cells and about60 billion white blood cells. Everysecond about 2 million new redblood cells are made in the bonemarrow to replace those that die atthe end of their 120-day life span.Have students calculate how manynew red blood cells are made everyhour. ([2,000,000 cells/s] �[60 s/min] � [60 min/h] �7,200,000,000 cells/h) Logical

DemonstrationAdd red water to a test tube tomake it about 40 percent full. Thencarefully add vegetable oil until thetest tube is full. Explain to studentsthat the fluids in the test tuberesemble a centrifuged blood sam-ple. Centrifuging pulls the heaviercomponents to the bottom of thetube. Lighter components stay atthe top. The vegetable oil repre-sents plasma, a yellow fluid. Thered water represents red bloodcells. Note that platelets and whiteblood cells, normally foundbetween the two layers, are notrepresented in this model. VisualBio 3E, Bio 5A

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TAKS 2 Bio 4BLS

BUILDERSKILL



MISCONCEPTION ALERT

The Color of Blood Students might thinkthat blood is one of two colors, red or blue.Diagrams that portray bright red arteriesand deep blue veins may enhance students’confusion. Oxygenated blood is, in fact,scarlet in color, while deoxygenated bloodis maroon, closer to dark red than to blue.The blue color seen in the superficial veinsof a person with fair skin is misleading: theskin and connective tissue that overlie theveins distort the true color of the bloodwithin the veins. Bio 5A

Answer

Student answers will vary, butshould be well researched.Students should present theirresearch results to the class.

Bio 11C

Real Life

StrategiesStrategiesINCLUSIONINCLUSION

Have students create a poster or bulletinboard of the Lymphatic System. UsingFigure 4, have students label the differentlymphatic tissues found in the body. Theymay add note cards describing the functionof each of the tissues and attach them to theposter or bulletin board. They may be ableto present their findings to the class and beable to tell how doctors use lymph nodes todetect infection. TAKS 2 Bio 10A; Bio 3E

• Learning Disability • Attention DeficitDisorder

Real LifeSeveral proteins fromvampire bats stop bloodfrom clotting. These proteins, includingone named draculin, arebeing used to developdrugs to fight heartdisease. Finding Information Investigate other drugsthat are currently beingdeveloped to help fightheart disease.

Components of BloodBlood has been called the river of life because it is responsible fortransporting so many substances throughout the body. In life-threatening situations, a person’s blood volume is carefully moni-tored, as shown in Figure 5. Typically, blood appears to us as a red,watery fluid. Blood is composed of water, but it also contains a vari-ety of molecules dissolved or suspended in the water, as well asthree kinds of cells.

Plasma About 60 percent of the total volume of blood is , the liquidportion of blood. Plasma is made of 90 percent water and 10 percentsolutes. The solutes include metabolites, wastes, salts, and proteins.

Water Water in the plasma acts as a solvent. It carries other substances.

Metabolites and Wastes Dissolved within the plasma are glucoseand other nutrient molecules. Vitamins, hormones, gases, andnitrogen-containing wastes are also found in plasma.

Salts (Ions) Salts are dissolved in the plasma as ions. The chiefplasma ions are sodium, chloride, and bicarbonate. The ions havemany functions, including maintaining osmotic balance and regu-lating the pH of the blood and the permeability of cell membranes.

Proteins Plasma proteins, the most abundant solutes in plasma,play a role in maintaining the osmotic balance between the cyto-plasm of cells and that of plasma. Water does not move by osmosisfrom the plasma to cells because the plasma is rich in dissolved pro-teins. In fact, the total amount of protein in cells and in plasma isthe same, making cytoplasm and plasma essentially isotonic withrespect to each other.

Some plasma proteins help thicken the blood. The thickness ofblood determines how easily it flows through blood vessels. Other

plasma proteins serve as antibodies, defending the body from disease. Still other plasma proteins, called clotting pro-teins or blood-clotting factors, play a major role in bloodclotting. When blood is collected for clinical purposes, theblood-clotting factors are removed from the blood and storedfor later use.

Blood Cells and Cell Fragments About 40 percent of the total volume of blood is cells and cellfragments that are suspended in the plasma. There are threeprincipal types of cells in human blood: red blood cells, whiteblood cells, and platelets.

Red blood cells Most of the cells that make up blood are—cells that carry oxygen. Each milliliter of

human blood contains about 5 million red blood cells. Redblood cells are also called erythrocytes (eh RIHTH roh seyets).

red blood cells

plasma

Figure 5 The river of life.The loss of too much bloodcan create a life-threateningsituation.

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Student Edition TAKS Obj 2 Bio 4B TAKS Obj 2 Bio 10A TAKS Obj 2 Bio 10B TEKS Bio 4B, 10A, 10B, 11C

Teacher Edition TAKS Obj 2 Bio 4B TAKS Obj 2 Bio 6C TAKS Obj 2 Bio 10A TEKS Bio 3E, 4B, 5A, 5C, 6C, 11C, 11D

pp. 876–877

Using the FigureRefer students to Figure 6. Havestudents relate the shapes and sizesof the cells and cell fragments inthe figure to their functions. (Redblood cells have a large surface areafor gas diffusion, and the characteris-tic “donut” shape enables them tosqueeze through tiny capillaries. Theshape of the white blood cells enablesthem to engulf other particles, andtheir size ensures that they can defendthe body against a large number ofinvaders. The shape of the plateletsallows them to stick together to forma small plug.) Have students com-pare the pictures with preparedmicroscope slides of human blood.

Visual

ActivityBlood Composition Blood hasseveral different components, andlearning them can be confusing.Have students construct aGraphic Organizer, such as theone shown at the bottom of thispage, that describes the structureand function of each of the bloodcomponents discussed in the text.Students should also show thecomposition of plasma, the fluidportion of the blood. Visual

Group ActivityBlood Diseases Have studentswork in small groups to conductlibrary or Internet research on dis-eases and disorders of the bloodand blood vessels. (Some examplesof diseases they could investigateinclude cancers such as leukemiaand lymphoma, anemia, sickle-celldisease, hemophilia, Raynaud’sphenomenon, thalassemia, and vonWillebrand disease.) Studentsshould collect information on thecauses, symptoms, treatment, andother pertinent information. Haveeach group prepare a report topresent to the entire class.TAKS 2 Bio 6C; Bio 11D

TAKS 2 Bio 4BLS

GENERAL

TAKS 2 Bio 4B; Bio 5A, 5CLS

GENERAL


Graphic Organizer

Blood

Metabolites

Wastes

Salts

Proteins

Platelets—blood clotting

Plasma—liquid portion of blood

Red blood cells—carry oxygen

White blood cells—defend body against disease

Use this graphic organizerwith Activity on this page.

Most of the interior of a red blood cell is packed with hemo-globin. Hemoglobin is an iron-containing protein that binds oxygenin the lungs and transports it to the tissues of the body. Mature redblood cells do not have nuclei and therefore cannot make proteinsor repair themselves. The absence of a nucleus gives a red blood cellits biconcave shape, as shown in Figure 6, and a short life span(about 4 months). New red blood cells are produced constantly bystem cells, specialized cells in bone marrow.

An abnormality in the number or function of red blood cells canresult in anemia. (uh NEE mee uh) is a condition in whichthe oxygen-carrying ability of the blood is reduced. Anemia mayresult from blood loss or nutritional deficiencies.

White Blood Cells There are only 1 or 2 white blood cells, or leukocytes (LOO koh sites), for every 1,000 red blood cells.

are cells whose primary job is to defend the bodyagainst disease. White blood cells, shown in Figure 6, are largerthan red blood cells and contain nuclei.

There are many different kinds of white blood cells, each with adifferent immune function. For example, some white blood cellstake in and then destroy bacteria and viruses. Other white bloodcells produce antibodies, proteins that mark foreign substances fordestruction by other cells of the immune system.

Platelets In certain large cells in bone marrow, bits of cytoplasmare regularly pinched off. These cell fragments, called (PLAYT lihts), are shown in Figure 6. Platelets play an importantrole in the clotting of blood. If a hole develops in a blood vesselwall, rapid action must be taken by the body, or blood will leak outof the system and death could occur.

When circulating platelets arrive at the site of a broken vessel,they assume an irregular shape, get larger, and release a substancethat makes them very sticky. The platelets then attach to the proteinfibers on the wall of the broken blood vessel and eventually form asticky clump that plugs the hole.

platelets

White blood cells

Anemia

Red blood cells White blood cell Platelets

Figure 6 Three kinds ofblood cells. Red blood cellstransport oxygen and somecarbon dioxide. White bloodcells help defend the bodyagainst disease. Platelets areinvolved in blood clotting.

www.scilinks.orgTopic: White Blood CellsKeyword: HX4190

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Teaching TipBlood Clotting Tell students thatwhen people cut themselves shaving,they often put a piece of tissue overthe cut. The fibers in the tissue actlike platelets, beginning the clottingprocess by providing a frameworkfor red blood cells to be caught.TAKS 2 Bio 4B



Blood DopingTeaching StrategiesBring in articles about otherperformance-enhancing (butoften prohibited) practices,such as the use of steroids andcertain nutritional supplementsfor athletes. Explain how theyhelp an athlete’s performancebut harm an athlete’s health.

Discussion• Why do you think the plasma

is reinjected immediately? (tokeep blood volume constant)

• Explain the physiologicaleffects of blood doping andthe reasons for these effects.(increased endurance due tomore oxygen in the blood;decreased heart rate; decreasedlactic acid in muscles due toincreased oxygen, increased aer-obic respiration, and decreasedanaerobic respiration)

• Why would doped blood clotmore easily? (There are moresolids in it.)

TECHNOLOGYTECHNOLOGYCONNECTIONCONNECTION

blood clotting proteins are imbedded in a film, which is freeze-dried onto the bandage.The bandage is pressure-applied, which helpsactivate its clotting agents, which set in about a minute. The bandage is lightweight and can be stored at room temperature, but it must bepacked in a watertight seal or it will “clot” inthe bag by absorbing water from the air. Drybandages retard chemical breakdown andnegate the need for refrigeration, importantcharacteristics for a field dressing. Bio/IPC 3C

Since uncontrolled bleeding is the most commoncause of death for soldiers wounded on the bat-tlefield, military medical researchers have longsought improved bandages that can be used inthe front lines. Army medical researchers havehelped to develop an improved field bandagethat can reduce bleeding by as much as 85 percent compared to previous dressings. Nowundergoing testing, the new bandage containsblood-clotting proteins. It is about four inchessquare and a quarter of an inch thick. The

Transparencies

TT Blood Clotting CascadeTT Systemic Circulation

For wounds such as an open cut, the plateletsrelease a clotting enzyme that activates a series ofchemical reactions. Eventually, a protein called fib-rin is formed. The fibrin threads form a net, trappingblood cells and platelets, as shown in Figure 7. Thenet of fibrin and platelets develops into a mass, orclot, that plugs the blood vessel hole. A mutation ina gene for one of the blood-clotting proteins causeshemophilia, a blood clotting disorder.

Blood Type Occasionally, an injury or disorder is so seriousthat a person must receive blood or blood compo-nents from another person. The blood types of therecipient, the person receiving the blood, and thatof the donor, the person giving the blood, mustmatch. Blood type is genetically determined by thepresence or absence of a specific complex carbo-hydrate found on the surface of red blood cells.

One system used to type blood is the. Under this system, the

primary blood types are A, B, AB, and O. The let-ters A and B refer to complex carbohydrates on the surface of red blood cells that act as antigens,substances that can provoke an immune response.

ABO blood group system

Platelets releaseclotting protein

(enzyme)

Fibrin net forms,trapping blood cells

and platelets

Clotting reaction occurs

Blood vessel damage

Stimulus

Blood clot

Result

Fibrin net Blood cells

Most athletes try to gain an edge over their competitors

through conditioning programsand longer hours in training.Some, however, turn to artificialmethods, such as blood doping.

What Is Blood Doping? Blood doping is a practice usedby some athletes to increase theamount of oxygen their blood cancarry by elevating the number ofred blood cells in their body. Sev-eral months before a competition,some of the athlete’s blood isdrawn. The plasma is separatedfrom the cells. The blood cells arefrozen. The plasma is immedi-ately injected back into theathlete’s bloodstream.

The body senses its deficiencyof red blood cells, and steps up itsproduction of red blood cells. After1 to 2 months, the entire proce-dure may be repeated. A few daysbefore an athletic competition, thefrozen blood cells are thawed andinjected into the athlete, temporar-ily bringing the athlete’s red bloodcell count above normal.

Does Blood Doping Work?Athletes who use blood dopingshow an increase in endurancewhile running on a treadmill, adecrease in their heart rate duringexercise, and a reduction in thelevel of lactic acid in their blood.

The Risks of Blood Doping The risks of blood doping faroutweigh the benefits. The bloodclots more easily, raising therisks of heart attack and stroke.Air bubbles are sometimes acci-dentally injected, and blood cellsare sometimes contaminatedwhile out of the body.

Athletes who inject bloodcells taken from another personface the dangers of blood in-compatibility and transmissionof diseases, including AIDS andhepatitis. For these and otherreasons, blood doping has beenprohibited by many sports-governing bodies.

Blood Doping

Figure 7 Blood-clotting cascade

The release of enzymes from platelets at the site of a damaged blood vessel initiates a “clotting cascade.”

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Student Edition TAKS Obj 2 Bio 4B TAKS Obj 2 Bio 10A TAKS Obj 2 Bio 10B TEKS Bio 4B, 10A, 10B

Teacher Edition TAKS Obj 2 Bio 4B, 10A, 10B TEKS Bio 4B, 10A, 10BTEKS Bio/IPC 3C

pp. 878–879

TAKS 2 Bio 4B, 10A

TAKS 2

Answers to Section Review

1. the cardiovascular system2. arteries—thick, elastic walls and thick smooth

muscle layers that carry blood under high pres-sure away from the heart; veins—thin wallsand thin smooth muscle layers that carry bloodunder low pressure to heart; capillaries—thinwalls that allow exchange of substances in theblood with the tissues

3. The lymphatic system collects and recycles flu-ids leaked from the circulatory system and isinvolved in fighting infections. TAKS 2 Bio 10A

TAKS 2 Bio 10A

TAKS 2 Bio 10A, 10B 4. Water is the solvent for dissolved substances inthe blood. Red blood cells carry oxygen to bodytissues. White blood cells defend the bodyagainst pathogens. Platelets help keep the venoussystem intact by patching tears in blood vessels.

5. A and O are both safe.6. A. Incorrect. There are no

O antigens. B. Incorrect. Both antigens are not present. C. Incorrect. Neither antigen ispresent. D. Correct. Type O has neither A nor B antigens. TAKS 2 Bio 10A

TAKS 2 Bio 10A, 10BTAKS 2 Bio 10B

ReteachingHave students observe preparedslides of normal blood and bloodwith abnormalities such asleukemia (cancer of the whiteblood cells) or an iron deficiency.Have them compare and contrastwhat they see. (With leukemia, thenumber of white cells may be greater.An iron deficiency may cause the redcells to be lighter in color and fewerin number.)

Quiz1. Which type of blood vessel is

involved in the exchange ofmaterials between the blood andbody tissues? (capillaries)

2.What happens to excess fluidthat collects in body tissues? (It is picked up in lymph vesselsand returned to the cardiovascularsystem.)

3. Which type of blood cell is thesmallest whole cell?(red blood cell)

AlternativeAssessmentHave students explain the adaptivevalue of the location of arteries(generally found far below thebody’s surface), veins (locatedcloser to the surface), and capillar-ies (distributed all over the body).(Arteries carry blood under high pressure, so a tear or rupture is morelife threatening than it is in a vein.Therefore it is beneficial to protectarteries deep within the body.Capillaries must come into contactwith every cell in the body to performtheir exchange function.)TAKS 2 Bio 10A

GENERAL

TAKS 2 Bio 4B

TAKS 2 Bio 10B

TAKS 2 Bio 10B

GENERAL

TAKS 2 Bio 4B

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As summarized in Table 1, people with type A blood have the A antigen on their red blood cells. People with type B blood have theB antigen. People with type AB blood have both the A and the Bantigen, while those with type O blood have neither antigen.

Antibodies are defensive proteins made by the immune system. Peo-ple with type A blood produce antibodies against the B antigen, evenif they have never been exposed to it. In these people, type B red bloodcells clump and can block blood flow. For this reason, blood transfu-sion recipients must receive blood that is compatible with their own.

People with type AB blood are universal recipients (they canreceive A, B, AB, or O blood) because they do not have anti-A oranti-B antibodies. Type O individuals are universal donors (they candonate blood to those with A, B, AB or O blood) because their bloodcells do not carry A or B antigens and therefore do not react witheither anti-A or anti-B antibodies.

Rh Factor Another important antigen on the surface of red blood cells iscalled , which was originally identified in rhesus mon-keys. People who have this protein are said to be Rh�, and thosewho lack it are Rh�. When an Rh� mother gives birth to an Rh�

infant, the Rh� mother begins to make anti-Rh antibodies. Themother’s antibodies may be passed to an Rh� fetus in a future preg-nancy, which can lead to fetal death.

Rh factor

Table 1 Blood Types

Blood Antigen on the Antibodies Can receive Can donate type red blood cell in plasma blood from blood to

A A B O, A A, AB

B B A O, B B, AB

AB A, B Neither A nor B O, A, B, AB AB

O Neither A nor B A, B O O, A, B, AB

Section 1 Review

Name the system that transports nutrients, oxygen,wastes, hormones, and heat.

Compare the structures and functions ofarteries, capillaries, and veins.

Describe the role of the lymphatic system.

Summarize the functions of water, red bloodcells, white blood cells, and platelets.

Predict the blood types that would be safe for a person with type A blood to receive during atransfusion. 10A 10B

10B

10A

10A

10A 10B

Real LifeRhoGAM is a bloodproduct that can sup-press the ability torespond to Rh� redblood cells. It is given to an Rh�

woman who is pregnantwith an Rh� fetus to pre-vent her from developingantibodies that wouldharm her baby.

Which antigens are on the redblood cells of a person with type O blood. A 0 antigens C Either A or B antigensB Both A and B D Neither A nor B

antigens antigens

10A

TAKS Test PrepTAKS Test Prep

www.scilinks.orgTopic: Cardiovascular

Research in TexasKeyword: HXX4005

879

OverviewBefore beginning this sectionreview with your students theobjectives listed in the StudentEdition. Students will map how thestructures of the cardiovascular sys-tem pump blood around the body.They will also describe electricalactivity in the heart. Finally, theywill list some disorders of the heart.

Ask students to write a few sen-tences that describe how the muscletissue of the heart is different fromother types of muscle tissue.(Answers may vary.)

DemonstrationShow students that when blood isfar from the heart, it travels withless pressure. You will need plasticsyringes and two pieces of hosingthat fit snugly on their ends. Onehose should be about 8 cm (3 in.)long and the other about 15 cm(6 in.). Fill each syringe and forcethe water out. The stream shouldtravel about 8 to 15 cm (3 to 6 in.)from the end of the longer hose(vein), and 15 to 30 cm (6 to12 in.) from the end of the shorterhose (capillary). Be sure to applyequal pressure to the plunger eachtime so students appreciate the factthat it is distance from plunger tipto exit, not pressure on the plunger,that causes the change. VisualTAKS 1 Bio/IPC 2A; TAKS 2 Bio 10A

LS

MotivateMotivate

TAKS 2 Bio 10A; Bio 5A

Bellringer

FocusFocus

Section 2

880 Chapter 38 • Circulatory and Respiratory System

• Lesson Plan• Directed Reading• Problem Solving GENERAL

GENERAL

Chapter Resource File• Reading Organizers• Reading Strategies • Problem Solving Worksheet

Computing Rates and HeartEfficiency GENERAL

Planner CD-ROM

Transparencies

TT BellringerTT Circulatory Loops in the Human BodyTT Path of Bloodflow Through the HeartTT Electrical Regulation of the Heart

Section 2 The Heart

A Muscular PumpBlood vessels allow for the movement of blood to all cells in thebody. The pumping action of the heart, however, is needed to pro-vide enough pressure to move blood throughout the body. The heartis made up mostly of cardiac muscle tissue, which contracts topump blood.

Two Separate Circulatory Loops As shown in Figure 8, the human heart has two separate circulatoryloops. The right side of the heart is responsible for driving the pul-monary (PUHL muh nehr ee) circulation loop, which pumpsoxygen-poor blood through the pulmonary arteries to the lungs.Gas exchange—the release of carbon dioxide and pick up of oxy-gen—occurs in the lungs. The oxygenated blood is then returned tothe left side of the heart through pulmonary veins.

The left side of the heart is responsible for driving the systemiccirculation loop, which pumps oxygen-rich blood through a net-work of arteries to the tissues of the body. Oxygen-poor blood isthen returned to the right side of the heart through the veins.

Objectives● Differentiate the pulmonary

circulation loop from the systemic circulation loop.

● Summarize the path thatblood follows through theheart.

● Name the cluster of heartcells that initiates contractionof the heart.

● Describe three ways tomonitor the health of the circulatory system.

● Name two vascular diseases,and identify factors thatcontribute to theirdevelopment.

Key Terms

atriumventriclevena cavaaortacoronary arterysinoatrial nodeblood pressurepulseheart attackstroke

Veins

Valves

Capillaries

Arteries

Pulmonaryvein

Pulmonarycirculation

Pulmonaryartery

Lungcapillaries

Systemiccirculation

Oxygen-poor blood Oxygen-rich blood

The pulmonary circuit transports blood between the heart and lungs; the systemic circuit transports blood between the heart and the rest of the body.

Figure 8 Simplified diagram mapping

10A

10A

10A

10A

11C

880


Teacher Edition TAKS Obj 1 Bio/IPC 2A TAKS Obj 2 Bio 10A, 10BTEKS Bio 5A, 10A, 10B, 11CTEKS Bio/IPC 2A

pp. 880–881

TAKS 2

TAKS 2

TAKS 2

TAKS 2

Teaching TipNourishing the Heart Point outto students that the heart cannot getnutrients and oxygen from the bloodin its own chambers. This is becausethe heart muscle is too thick for dif-fusion to be an effective means ofdistribution. Instead, the heart mustrely on the coronary arteries to sustain it. These two arteries lie ingrooves that spiral around the heart.An obstruction in one of theirbranches often necessitates bypasssurgery to restore proper blood flowto the heart. Restricted blood flowcan result in angina pectoris, whichis chest pain, or a myocardial infarc-tion, which is a heart attack. Heartcells die during an infarction, whichlimits the heart’s pumpingefficiency.

Using the FigureHave students examine Figure 9.Have them use their fingers to tracethe path that blood follows throughthe heart. Tell students that althoughthe heartbeat is described for con-venience as occurring first on theright side and then on the left, themovement of blood occurs on bothsides simultaneously. Have studentscompare the sizes of the left andright ventricle walls. Ask why theleft ventricle wall is thicker than theright. (Blood is pumped to the entirebody from the left ventricle. Bloodfrom the right ventricle goes only asfar as the lungs.) Visual

DemonstrationShow students a transparency containing a diagram of a fish’s car-diovascular system. Point out thatthe fish’s cardiovascular system hasonly one circuit in it, rather than thetwo circuits found in mammals.Trace the pathway of blood fromthe heart, over the gills, to body tissues, and back to the heart. Askstudents why the number of cardio-vascular system circuits of fish andmammals might be different. (Fishare ectothermic animals that havelower metabolic demands than mam-mals; therefore, their needs for oxygenare also lower.) TAKS 1 Bio/IPC 2A

GENERAL

TAKS 1 Bio/IPC 2ALS

TAKS 2 Bio 10A, 10B (grade 11 only)

TeachTeach


increasing the heart rate and/or by increasingthe strength of the heart beat. The reductionin vascular resistance results in higher levels of oxygen being delivered to body tissues. A conditioned athlete’s resting heart rate islower than that of an unconditioned person.The athlete’s cardiac output is also greaterthan an unconditioned person’s. Going from the resting to maximal exercise states,oxygen consumption increases by 10 times in untrained people and by 20 to 30 times inconditioned athletes. TAKS 2 Bio 10A; Bio 11C

Aerobic exercise conditions the heart andlungs by increasing the oxygen available to the body and by enabling the heart to use oxygen more efficiently. During dynamic aerobic exercise, such as walking, tennis, soccer, and volleyball, the cardiorespiratorysystem responds by increasing oxygen supplyto the muscles. This occurs as a result of thenervous system increasing cardiac output andreducing vascular resistance in small bloodvessels. Cardiac output (the amount of bloodpumped with each heart beat) is increased by

REAL WORLDREAL WORLDCONNECTIONCONNECTION

Circulation of BloodAs shown in Figure 9, the heart has a wall that divides the right andleft sides of the heart. At the top of the heart are the left and rightatria (AY tree uh). The (singular, atrium), are chambers thatreceive blood returning to the heart. Below the atria are the left andright , thick-walled chambers that pump blood awayfrom the heart. A series of one-way valves in the heart prevent bloodfrom moving backward. Figure 9 summarizes the path bloodfollows through the heart:

Two large veins called the inferior and superior venacava collect all of the oxygen-poor blood from the body. Thevenae cavae empty blood directly into the right atrium of theheart.

The blood from the right atrium moves into the right ventricle.

As the right ventricle contracts, it sends the blood into the pul-monary arteries.

The pulmonary arteries carry the blood to the right and leftlungs. At the capillaries of the lungs, oxygen is picked up andcarbon dioxide is unloaded.

The freshly oxygenated blood returns from the lungs to the leftside of the heart through the pulmonary veins, which empty theblood directly into the left atrium.

From the left atrium, the blood is pumped into the left ventricle.

vena cava

ventricles

atria Interpreting GraphicsIn human anatomy, theterms left and right alwaysrefer to the left and rightfrom the perspective of thesubject. This will help youunderstand why the termsleft and right appearreversed in anatomicaldrawings, such as that of the heart in Figures 8 and 9.

Superior vena cavasends O2-poor blood from upper body toright atrium.

Blood from aorta to body

Aorta sends blood to the coronaryarteries, the brain, and the rest ofthe body.

Pulmonary veinsreturn blood to the left atrium from the lungs.

Left atriumsends blood to theleft ventricle.

Left ventriclesends blood to the aorta.

Right atriumsends blood to theright ventricle.

Right ventriclesends blood to thepulmonary artery.

Left lungRight lung

Inferior vena cavasends O2-poor bloodfrom lower body toright atrium.

Pulmonary arteriessend blood to the lungs.

The arrows trace the path of blood as it travels through the heart.

Figure 9 Blood flow through the heart

881

Teaching TipThe Intrinsic Heartbeat Pointout to students that cardiac musclecells have an intrinsic, or self-initiated, beat. Contractions of theheart muscle are not produced bystimulation from nerves. Nervescontrol only the rate of the heart’scontractions. In addition, cardiacmuscle cells influence each other.The sinoatrial node and the atrio-ventricular node (which stimulatesthe ventricles to contract) triggercontractions of the other heartmuscle cells in the same chamber.Thus, contraction of the cells of theatria and then of the ventricles issynchronized.

Demonstration Invite the school nurse to demon-strate how a stethoscope can beused to hear the sounds of a heart-beat. Tell students that the “lubb”and “dup” sounds that are heardare made when the valves of theheart close. Explain that the valvesof the heart open with each con-traction and let blood through tothe next chamber or to an artery.The valves then close to stop bloodfrom moving backward. In thisway, the valves keep blood movingthrough the heart and out to thebody. Valve disease occurs when avalve doesn’t work the way itshould. If a valve doesn’t open allthe way, less blood can movethrough the smaller opening. If avalve doesn’t close tightly, bloodmay leak backward. A heart mur-mur is an abnormal sound that canbe heard when listening to a per-son’s heartbeat. TAKS 2 Bio 10A

TAKS 2 Bio 10A; Bio 5A, 11A



TECHNOLOGYTECHNOLOGYCONNECTIONCONNECTION

that helps the heart beat in a regular rhythm.Some pacemakers are permanently implantedin the chest wall, and some are worn exter-nally. The pacemaker sends electrical impulsesto the heart, which helps to regulate theheart’s rhythm. An electrode is placed next tothe heart wall and small electrical chargestravel through the wire to the heart.TAKS 2 Bio 10A; Bio/IPC 3C

When the heart’s rhythm is disrupted causingthe heartbeat to be too fast, too slow, or irregular, an artificial pacemaker may becomenecessary. These disruptions may be caused bya blockage in the electrical pathway that regu-lates heart rhythm, or by some other defect inthe heart’s natural pacemaker. An artificialpacemaker is a small, battery-operated device

Sinoatrial(SA) node

After a slight delay that permits the left atrium to empty com-pletely, the left ventricle contracts. The walls of the left ventricleare muscular, so the left ventricle’s contraction is forceful.

The blood then enters one of the largest arteries of the body, the(ay OHR tuh).

The first arteries to branch from the aorta are the (KOHR uh neh ree) , which carry freshly oxygenated bloodto the heart muscle. Other arteries also branch from the aorta andcarry oxygen-rich blood to all parts of the body.

After delivering oxygen to the cells of the body and picking upcarbon dioxide, the cycle continues when blood returns to the heartthrough the inferior or superior venae cavae.

Initiating ContractionContraction of the heart is initiated by a small cluster of cardiac mus-cle cells called the (SIE noh ay tree uhl) , which isembedded in the upper wall of the right atrium. The cells that makeup the sinoatrial node (SA node, for short) act as the pacemaker ofthe heart. These cells “fire” an electrical stimulus in a regularrhythm. Each stimulus is followed immediately by a contraction thattravels quickly in a wave and causes both atria to contract almostsimultaneously, as shown in Figure 10.

The wave of contraction spreads from the atria to the ventricles,but almost one-tenth of a second passes before the ventricles startto contract. The delay permits the atria to finish emptying bloodinto the ventricles before the ventricles contract simultaneously.The wave of contraction is conducted rapidly over both ventriclesby a network of nerve fibers in the heart.

On average, heart contractions occur at a rate of about 72 timesper minute. During sleep the rate decreases, and during exercise itincreases. The SA node is controlled by two sets of nerves withantagonistic (opposite) signals and is influenced by many factors,including hormones, temperature, and exercise.

Monitoring the Cardiovascular SystemHeart disease is one of the leading causes of death among people inthe United States. Health professionals use several different meth-ods to monitor the health of the circulatory system.

Blood pressure Doctors routinely measure patients’ blood pressure.is the force exerted by blood as it moves through

blood vessels. Blood pressure readings provide information aboutthe conditions of the arteries.

Blood pressure is measured with a blood pressure cuff and gauge,shown in Figure 11. Blood pressure is expressed in terms of mil-limeters of mercury (mm Hg) and is usually reported as the systolicpressure written over the diastolic pressure. The first number, thesystolic pressure, is the pressure exerted when the heart contractsand blood flows through the arteries. The diastolic pressure is thepressure exerted when the heart relaxes.

Blood pressure

nodesinoatrial

arteriescoronary

aorta

Figure 10 Electrical regulation of the heart. TheSA node, or pacemaker, firesahead of each heart contrac-tion. The wave of contractionspreads across both atria anddelays for an instant before ittravels to the ventricles.

Figure 11 Monitoringblood pressure. Bloodpressure is measured with a blood pressure cuff, astethoscope, and a mercury(Hg) column gauge.

882

Student Edition TAKS Obj 2 Bio 10A TAKS Obj 2 Bio 10B TEKS Bio 10A, 10B

Teacher Edition TAKS Obj 2 Bio 10A TEKS Bio 5A, 11A, 11B, 11C TEKS Bio/IPC 3C

pp. 882–883

Teaching TipHeart Attacks Tell students thathypertension, or high blood pres-sure, is a serious health conditionbecause it is the major cause ofheart failure, kidney failure, andstroke. Ask students to use outsidesources to research hypertensionand prepare a report that explainsthe causes of this condition, how itcan be prevented or treated, andthe incidence of hypertension in theUnited States compared with thatof other countries.

Group ActivityMeasuring Blood Pressure Havethe school nurse demonstrate howa sphygmomanometer works.Remind students that blood pres-sure readings include two numbers,the systolic and diastolic pressures,represented as a ratio. The systolicreading, the first value, is the pres-sure on the artery walls exerted bythe contracting ventricles. The dias-tolic reading, the second value, isthe pressure on the blood vesselwalls during ventricular relaxation.

GENERAL

Bio 11B, 11C


What Is a Heart Attack?Teaching StrategiesBring in a sheep heart or apicture of a human heart andpoint out the coronary arteriesto students.

Discussion• Identify the ways arteries

become blocked. (blood clots,atherosclerosis, arteriosclerosis)

• Why do doctors recommendthat certain people take anaspirin a day? (Aspirin acts asan anticoagulant, keeping theblood flowing.)

• How can aspirin help preventheart attacks? (Thinner bloodis less likely to clot, but it willnot prevent plaques from com-ing loose or other causes forheart attacks.)

Obesity Health problems resulting fromoverweight and obesity could reverse manyof the health gains achieved in the U.S. inrecent decades, according to a SurgeonGeneral’s “call to action” issued inDecember of 2001. “Overweight and obe-sity may soon cause as much preventabledisease and death as cigarette smoking,”then Surgeon General David Satcher said.Being overweight is a risk factor for heartdisease, high blood pressure, diabetes, somecancers, asthma, and other conditions.

Approximately 300,000 U.S. deaths a yearcurrently are associated with obesity and over-weight (compared to more than 400,000 deathsa year associated with cigarette smoking). Thetotal direct and indirect costs attributed tooverweight and obesity amounted to $117billion in the year 2000. In 1999, an estimated61 percent of U.S. adults were overweight,along with 13 percent of children and adoles-cents. Obesity among adults has doubled since1980, while the number of overweight adoles-cents has tripled. TAKS 2 Bio 10A; Bio 11C

Transparencies

TT ElectrocardiogramTT Electric Regulation of the Heart

Normal blood pressure values are from 100 to 130 for systolicpressure and from 70 to 90 for diastolic pressure. An example of anormal reading would be written 120/80 mm Hg. These figuresindicate the blood is pushing against the artery walls with a pres-sure of 120 mm Hg as the heart contracts and 80 mm Hg as theheart rests.

Many Americans suffer from a condition called high blood pres-sure, or hypertension. High blood pressure places a strain on thewalls of the arteries and increases the chance that a vessel will burst.Left untreated, hypertension can lead to heart damage, brain dam-age, or kidney failure. Regular aerobic activity can help people tomaintain a healthy blood pressure. Hypertension can be easily diag-nosed and usually can be controlled by medicine, diet, and exercise.

Electrocardiograms (ECGs or EKGs) A common way to monitor theheart’s function is to measure the tiny electrical impulses producedby the heart muscle when it contracts. Because the human body iscomposed mostly of water with dissolved ions, it conducts electricalcurrents. A small portion of the heart’s electrical activity reaches thebody surface. As shown in Figure 12, an instrument called an electro-cardiograph uses special sensors to detect the electrical activity. Arecording of these electrical impulses is called an electrocardiogram,abbreviated as ECG or EKG. In one normal heartbeat, three succes-sive electrical-impulse waves are recorded, as shown in Figure 12.

Heart Rate It takes only a watch with a second hand to measureyour pulse. Your is a series of pressure waves within an arterycaused by the contractions of the left ventricle. A person’s pulse isan indicator of his or her heart rate—how fast or slow the heart isbeating. Each time the blood surges from the aorta, the elastic wallsin the blood vessels expand and stretch. This rhythmical expansioncan be felt as a pulse in areas where the vessel nears the surface ofthe skin. The number of pulses counted per minute represents thenumber of heartbeats per minute. The most common site for takinga pulse is at a radial artery, on the thumb side of each wrist. Theaverage pulse rate ranges from 70 to 90 beats per minute for adults.

pulse

Electrocardiogram

Atria contract Ventricles relax

Ventricles contract

Figure 12 Monitoringheart contractions. Theelectrical changes with eachheart contraction can bedetected with an electrocar-diograph. The characteristicup-and-down waves areanalyzed to assess the healthof the heart.

The Greek word for heart iskardia. Because of the k inthis word, electrocardiogramis sometimes abbreviated asEKG instead of ECG.

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TAKS 2 Bio 10A

ReteachingReview the Demonstration on thefirst page of this section. Havestudents infer which blood vesselwould have the highest blood pres-sure. (the aorta, as blood is leavingthe left ventricle) Which bloodvessel would have the lowest bloodpressure? (the vena cava, as blood isreturning to the right atrium) Havethem justify their choices.

Logical

Quiz1. Blood leaving the heart through

the pulmonary artery goes to________ . (the lungs)

2.How is a heartbeat stimulated?(by electrical stimuli from thesinoatrial (SA) node in the rightatrium that stimulates other heartcells to contract)

3. What is an EKG? (electrocardio-gram, a record of the electricalactivity of the heart)

4. What is a heart attack? (death ofan area of the heart that has hadits blood supply cut off)

AlternativeAssessmentHave students design a crosswordpuzzle using key vocabulary wordsfor the heart and circulation.

Verbal TAKS 2 Bio 10ALS

GENERAL

TAKS 2 Bio 10A; Bio 11A, 11B

GENERAL

TAKS 2 Bio 10A; Bio 3ELS

CloseClose


1. left atrium, left ventricle, aorta, arteries, capil-laries, veins, vena cava, right atrium, rightventricle, pulmonary arteries, lungs, and pul-monary veins

2. When the sinoatrial node is activated, it causesthe atria to contract. After about a one-tenth ofa second pause, the ventricles contract.

3. The SA node acts as a heart pacemaker by pro-viding an electrical stimulation that regulatesthe heart’s rhythm.

4. EKG, blood pressure, and pulse can be used tomonitor cardiovascular system condition.TAKS 2 Bio 10A

TAKS 2 Bio 10A

TAKS 2 Bio 10A

TAKS 2 Bio 10A

5. A heart attack occurs when a blood vessel inthe heart becomes blocked. A stroke occurswhen a blood vessel in the brain becomesblocked.

6. A. Correct. Blood moves fromthe right ventricle to the lungs for oxygenation,then back to the heart. B. Incorrect. Blood fromthe left ventricle enters the aorta. C. Incorrect.Blood moves from the right atrium to the rightventricle. D. Incorrect. Blood leaving the leftventricle moves to the rest of the body exceptthe lungs. TAKS 2 Bio 10A

TAKS 2 Bio 10A, 10B; Bio 11C


Diseases of the blood vessels serving the heart and brain are lead-ing causes of premature death and disability in the United States.When either the heart or the brain does not get enough blood, partsof the organ die. A occurs when an area of the heartmuscle stops working and dies. When an area of the brain dies theresult is a . Death or varying degrees of disability may result.Factors that contribute to heart attacks and strokes are cigarettesmoking, lack of physical activity, diets high in saturated fats, andunmanaged stress.

stroke

heart attack

What Is a Heart Attack?

You may feel a sharp, crushing, squeezing pain inyour chest. You may have mild pain in your jawsor down an arm. You may break into a cold sweatand feel nauseated. Some of these symptomsoccur in almost 2 million Americans each yearwhen they experience a heart attack. Some people experience almost no symptoms.

Why Do Heart Attacks Occur? Heart attacks usually happen when the arteriesthat deliver oxygen to the heart, the coronaryarteries, become blocked. Heart cells begin to die very quickly without blood. If a large part ofthe heart is affected, the victim can die immedi-ately or within a few days or weeks.

Blockage of ArteriesA blood clot formed somewhere else in the bodycan break loose and flow to the heart or to thebrain, where it blocks the flow of blood. Bloodflow is also blocked by the buildup of fattydeposits, including cholesterol, a condition calledatherosclerosis (ath uhr oh skluh ROH sihs).

When calcium is deposited in the fatty buildup,the condition is called arteriosclerosis (ahr tihr eeoh skluh ROH sihs), or hardening of the arteries.Hardened arteries cannot expand to handle thevolume of blood that enters every time the heartcontracts. Pressure builds up in the artery andcauses the heart to work harder.

PreventionHigh blood pressure, high cholesterol levels, andcigarette smoking are all controllable risk factorsin heart disease. Not smoking at all, early diagno-sis and treatment of high blood pressure, regularmedical checkups, a healthy diet, and regularexercise can all help prevent a heart attack ordecrease the severity of one.

FurtherExploring Further

Normal artery Artery with fatty deposits

Fat

Cholesterolcrystals

Summarize the path of blood through the bodystarting and ending with blood that has justreturned from the lungs to the heart. 10A

List the sequence of events that results in atrialand ventricular contraction. 10A

Describe the function of the SA node. 10A

Identify three ways that the condition of the cardiovascular system can be monitored. 10A

Differentiate between a heart attack and astroke. 10A 10B 11C

When the right ventriclecontracts, it pumps blood to the 10A

A lungs. C right atrium.B aorta. D rest of the body.


Section 2 Review

884


Teacher Edition TAKS Obj 2 Bio 4B TAKS Obj 2 Bio 10A TEKS Bio 3E, 4B, 10A, 11A, 11B,11C

pp. 884–885

TAKS 2

Section 3

OverviewBefore beginning this sectionreview with your students theobjectives listed in the StudentEdition. Students will sequence thestructures through which air passesas it enters and exits the body. Theywill describe the mechanism ofbreathing and how it is regulated.They will also explain how oxygenis transported in the blood, how itis exchanged with carbon dioxidein body tissues, and how carbondioxide is transported in the blood.Finally, students will develop anappreciation for the symptoms ofand treatments for several respira-tory diseases.

Ask students to write a sentence ortwo describing why their breathingrate would increase from exercise orfright. (In either case, the respiratorycenter in the brain would stimulatethe muscles involved in breathing toincrease their rate of contraction andprepare the body to meet either actualor potential oxygen needs.)

Discussion/QuestionPoint out that air pressure affectsrespiration in humans. Gases areexchanged between the air in thealveoli and the blood in the capil-laries entirely by diffusion. Havestudents postulate why a personbreathes deeper and faster at higheraltitudes, where there is decreasedpressure. (At high altitudes, hemo-globin’s affinity for oxygen is lower.At 6,000 m [9,000 ft], the oxygensaturation of hemoglobin is only 67percent, compared to 98 percent atsea level. One must become accli-mated over time to the low levels ofoxygen.) Athletes who train at highaltitudes tend to perform better inlower altitudes than those whotrain in low altitudes. LogicalTAKS 2 Bio 4B; Bio 11A, 11B

LS

GENERAL

MotivateMotivate

Bio 11B

Bellringer

FocusFocus


• Reading Organizers• Reading Strategies • Supplemental Reading Guide

Microbe Hunters• Occupational Application Worksheet

Respiratory Therapist GENERAL

Planner CD-ROM

Transparencies

TT BellringerTT The Human Respiratory System

• Lesson Plan• Directed Reading• Active Reading• Data Sheet for Math Lab• Data Sheet for Quick Lab GENERAL

GENERAL

GENERAL

GENERAL

Chapter Resource File

Gas ExchangeA person can go without water for a few days and without food formore than a week. But if a person stops breathing for more than afew minutes, he or she will die. Breathing is the means by whichyour body obtains and releases gases. Oxygen is used by your cellsto completely oxidize glucose and then make ATP, the main energycurrency in your cells. Without oxygen, your body cannot obtainenough energy from food to survive. Excess carbon dioxide pro-duced as a waste product of aerobic respiration is toxic to cells andmust be removed.

The Path of Air Breathing is only one part of gas exchange. The gases must betransported by the cardiovascular system and then exchanged atthe cells. All of the organs and tissues that function in this exchangeof gases make up the respiratory system, as shown in Figure 13.

A breath of air enters the respiratory system through the nose ormouth. Air is made up of many gases. About 21 percent of air isoxygen gas. Hairs in your nose filter dust and particles out of theair. Tissues that line the nasal cavity moisten and warm the air.

The Respiratory System Section 3

Objectives● Summarize the path that

air follows when it entersthe body through the noseor mouth.

● Describe the role of the ribmuscles and diaphragm inbreathing.

● Describe how breathingrate is regulated.

● Summarize how oxygenand carbon dioxide aretransported in the blood.

● Identify three seriousdiseases of the lungs.

Key Terms

pharynxlarynxtracheabronchusalveolusdiaphragm

Respiratory System

Diaphragm

Right lung

Bronchi

Pharynx

Trachea

Bronchioles

Larynx

Left lung

Alveoli

Capillaries

Figure 13 Taking in andexchanging gases. The respiratory passages, lungs,and thoracic cavity make upthe respiratory system.

10A

10A

10A

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TAKS 2

TAKS 2

TAKS 2

Teaching TipLarynx Point out to studentswhere the vocal cords—larynx—are found. Explain that sound isproduced when air is forced throughthe larynx. Also inform studentsthat laryngitis is simply an inflam-mation of the vocal cords in whichthey lose their ability to vibrate.Hence, people “lose their voice.”TAKS 2 Bio 10A

TeachTeach

Newborns In addition to using lungs for thefirst time, a newborn’s heart and cardiovascu-lar system change with the first breath. Anopening, the foramen ovale, lies between theleft and right atria. Another structure, the duc-tus arteriosus, connects the pulmonary arteryto the aorta. Upon inspiration for the firsttime, the lungs are inflated, closing the openingand separating pulmonary circulation from thesystemic circulation.TAKS 2 Bio 10B (grade 11 only)


Calculating theAmount of AirRespiredSkills AcquiredAnalyzing data, calculat-ing, inferring relationships

Teacher’s NotesEnsure that students understandthat units are important indimensional analysis.

Answers to Analysis

1. 15 breaths/min � 0.5 L/breath� 7.5 L/min

2. 7.5 L/min � 60 min/hr �450 L/hr

3. Answers will vary but mayinclude that infants havesmaller lungs, a faster heartrate, and a faster metabolism.

<x + 6x - 7 - 02

18

49376

0

52

StrategiesStrategiesINCLUSIONINCLUSION

Have students determine the average breath-ing rate for students in their class. The students should record how many breaths(inhale and exhale equals one breath) eachstudent takes for one minute. Have studentsadd each rate and divide by the number ofstudents included in the test to figure theaverage breathing rate. Additionally, studentsmay recruit adult volunteers and determinetheir breath rates and compare the resultswith those taken in class.TAKS 1 Bio/IPC 2C;TAKS 2 Bio 10A

• Attention Deficit Disorder • Learning Disabilities

Transparencies

TT Inhalation and Exhalation

From the nose, air passes through a muscular tube in the upperthroat called the (FAIR ingks), which serves as a passage-way for air and food. The air continues on through a passagewayfor air, called the (LAIR ingks), or voice box located in theneck. A flap of tissue, the epiglottis (ehp uh GLAHT ihs), covers theopening to the larynx when you swallow food and liquids. This pre-vents food and liquids from passing into your lungs.

From the larynx the air passes into the (TRAY kee uh), along, straight tube in the chest cavity. The trachea, or windpipe,divides into two smaller tubes, the (BRAHNG kie), whichlead to the lungs. Within the lung, the bronchi (singular, bronchus)divide into smaller and smaller tubes called bronchioles (BRAHNGkee ohls). The smallest bronchioles end in clusters of air sacs called

(al VEE uh lie), where gases are actually exchanged. Asshown in Figure 13, each of the 300 million small alveoli is sur-rounded by a jacket of capillaries. Alveoli increase the surface areaof your lungs to as much as 42 times the surface area of your body.

The cells that line the bronchi and trachea secrete mucus that trapsforeign particles in the air. The mucus is directed upward by cilia tothe epiglottis, where the mucus is swallowed and digested. Microbesin the mucus are destroyed by acids and enzymes in the stomach.

Lungs The lungs, which are among the largest organs in the body, are sus-pended in the chest cavity, bounded on the sides by the ribs and onthe bottom by the diaphragm (DIE uh fram). The is apowerful muscle spanning the rib cage under the lungs, and it aidsin respiration. A double membrane surrounds both lungs. The outer-most membrane is attached to the wall of the thoracic cavity, and theinner membrane is attached to the surface of the lungs. Betweenboth membranes is a small space filled with fluid.

diaphragm

alveoli

bronchi

trachea

larynx

pharynx

Analysis

1. Calculate the volume of airin liters an adult breathes perminute if his or her breathingrate is 15 breaths per minute.

2. Calculate the volume of airin liters an adult breathes perhour if his or her breathingrate is 15 breaths per minute.

3. Critical ThinkingInferring Conclusions Thebreathing rate of an infant isabout 40 breaths per minute.Why might infants have higherrespiratory rates than adults?

Calculating the Amount of Air Respired Background

Most adults take in about 0.5 L of air with each breath. The normal breathing rate is about 8 to 15 breaths per minute.

<x + 6x - 7 - 02

8

493 0

52

2C 2D

Real LifeThe lungs of humanfetuses do not functionuntil birth. A fetus’sumbilicalcord containsblood vesselsthat lead toand from theplacenta,which con-tains fetaland maternalcapillaries. The O2 in the mother’s capillariesdiffuses to the fetus’scapillaries, and the CO2in the fetus’s capillariesdiffuses into the mother’scapillaries. Finding Information Determine the signal thatstimulates the baby to startbreathing at birth. 11A

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Student Edition TAKS Obj 1 Bio/IPC 2C, 2DTAKS Obj 2 Bio 4B TAKS Obj 2 Bio 10A TAKS Obj 2 Bio 10B TEKS Bio 4B, 10A, 10BTEKS Bio/IPC 2C, 2D

Teacher Edition TAKS Obj 1 Bio/IPC 2C, 2D TAKS Obj 2 Bio 10A, 10B TEKS Bio 3D, 3E, 10A, 10B, 11C, 11DTEKS Bio/IPC 2C, 2D

pp. 886–887

TAKS 1

TAKS 1 Bio/IPC 2C, 2D

MATH TAKS Obj 9, 8.3; Obj 10, 8.14A, C, 8.16A

Teaching TipSpirometer Patients in hospitalsare at risk for lung infectionsbecause they are inactive. If a patientis bedridden, he or she must breathedeeply to get air deep into the lungsand help prevent fluids from accu-mulating there. Inhaled bacteria cangrow easily in warm, moist air andpatients can develop pneumonia.Hospital staff check a patient’s tidalvolume several times a day with aspirometer to ensure enough air isbeing expelled and inhaled.

Brainstorming Lead a class discus-sion on the mechanism of breathing.Ask for volunteers to describe thelocations of the muscles involved in breathing and what happens tothem during inhalation andexhalation. (A volunteer could drawsketches similar to those in Figure 14to illustrate the process.) Ask studentsif the walls of the lungs also havemuscles and, if so, are they involvedin breathing. (No.) Logical

DemonstrationDemonstrate how breathing worksby making a model of the lungsand diaphragm. You will need abell jar, one small balloon, a glasstube, a one-holed rubber stopper, athin rubber sheet, and a rubberband. Attach the deflated balloonto one end of the short glass tubethat has been inserted through theone-holed rubber stopper. Use thestopper to plug the mouth of a belljar, allowing the balloon to hanginside the jar. Use a rubber band tofasten a thin sheet of rubber overthe mouth of the jar. Pull down onthe rubber sheet, and have studentsobserve what happens to the bal-loon. Have students relate theirobservations to inhalation. Releasethe rubber sheet. Have them relatetheir observations to exhalation.Ask students the drawbacks of thismodel. (Chest muscles do not move;only one lung is shown.) VisualTAKS 2 Bio 10A; Bio 3E

LS

TAKS 2 Bio 10ALS

SKILLBUILDER

READINGREADING

Bio 11C, 11D

Chapter 38 • Circulatory and Respiratory System 887

problems that might arise during surgery or recovery. Anesthesiologists also work in intensive careunits to help restore critically ill patients to stable condition. Anesthesiologists are involvedin pain management, including diagnosis andtreatment of acute and chronic problems.The field of anesthesiology is growing andopportunities for employment are excellent.Starting salary will vary by subspecialty and region. Bio 3D

CareerCareerAnesthesiologists Anesthesiologists (anes-thetists) are physicians who complete a four-year college program, four years of graduatemedical training and four more years of anes-thesiology residency. Their primary role in theoperating room is to ensure the patient’s com-fort during surgery and also to make informedmedical judgments to protect the patient. Theseinclude treating and regulating changes in criti-cal life functions, including breathing, heartrate, and blood pressure. These specialistsimmediately diagnose and treat any medical

Breathing Air is drawn into and pushed out of the lungs by the mechanicalprocess known as breathing. Breathing occurs because of air pres-sure differences between the lungs and the atmosphere, as shown inFigure 14. To draw air into the lungs, a process called inhalation, therib muscles contract. This draws the rib cage up and out, and thediaphragm contracts, moving downward. The volume of the chestcavity increases, which reduces the air pressure within the cavitybelow the atmospheric pressure. Because air flows from a high pres-sure area to a low pressure area, air is drawn into the lungs.

Normal exhalation (breathing out) is a passive process. The ribcage and diaphragm muscles relax, which returns the rib cage anddiaphragm to their resting position. The relaxation of these musclesdecreases the volume in the chest cavity and increases the air pres-sure in the lungs. Because the air pressure is now higher in thelungs than in the atmosphere, air is forced out—from a high pres-sure area to a low pressure area.

Breathing Rate You took your first breath within moments of being born. Since then,you have repeated the process more than 200 million times. Whatcontrols how fast or slow you breathe? Receptors in the brain and car-diovascular system continually monitor the levels of oxygen andcarbon dioxide in the blood. The receptors enable the body toautomatically regulate oxygen and carbon dioxide concentrations bysending nerve signals to the brain. The brain responds by sendingnerve signals to the diaphragm and ribmuscles in order to speed or slow the rateof breathing.

It may surprise you to know that carbon dioxide levels have a greatereffect on breathing than do oxygen lev-els. For example, if the concentration ofcarbon dioxide in your blood increases,such as during exercise, you respond bybreathing more deeply, ridding yourbody of excess carbon dioxide. When thecarbon dioxide level drops, your breath-ing slows. Factors such as stress, pain,and fear also influence breathing rate.

The signals that travel from thebreathing center of the brain are not subject to voluntary control. You cannotsimply decide to stop breathing indefi-nitely. You can hold your breath for awhile, but even if you lose consciousnessyour respiratory control center will takeover and force your body to breathe.

Lung

Rib

Rib cagemuscles

Diaphragm

When the diaphragm contracts, it moves down and air rushes in.

Inhalation Exhalation

When the diaphragmrelaxes, it moves up and air is forced out.

The diaphragm and the muscles between the ribs are involvedin the movement of the chest cavity during breathing.

Figure 14 Inhalation and exhalation

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Reading Organizer Encouragestudents to keep a vocabulary note-book, a stack of vocabulary cards,or some other way of recordingand reviewing unfamiliar vocabu-lary. Each entry should include notonly the correct spelling of theword but also a definition, prefer-ably one in the student’s ownwords. This strategy will be espe-cially beneficial in a chapter likethis one, where students encountermany new terms. Visual

DemonstrationHave a volunteer gently blowthrough a straw into a beaker thatcontains a weak solution of bro-mothymol blue (BTB) and water.The color will change slowly togreen then yellow, indicating thepresence of CO2. Actually, BTB isan indicator of acid. The bicarbon-ate ions and carbonic acid createdby blowing air into the indicatormixture lower the pH of the indica-tor mixture which leads to thecolor change. VisualTAKS 4 IPC 9B (grade 11 only)

LS

LS

SKILLBUILDER

READINGREADING



CulturalAwarenessCulturalAwareness

Saving Lives In 1914, Barrett A. Morgan,an African American, invented the world’sfirst gas mask. Called by many names—breathing device, safety hood, gas inhalator—this clever invention won an award at theSecond International Exposition of Safetyand Sanitation in New York in 1914. Twoyears later it saved the lives of constructionworkers trapped in a smoke-filled tunnelbeneath Lake Erie. Bio/IPC 3C

GENERAL

Transparencies

TT O2 and CO2 in the Blood

Gas TransportBreathing is the first step to getting oxygen to the trillions of cellsin your body. When oxygen molecules diffuse from the air into youralveoli, their journey has just begun, as shown in Figure 15. As oxygen passes into the plasma of the bloodstream, it is picked up by red blood cells that carry an iron-containing protein calledhemoglobin.

Oxygen Transport Each hemoglobin molecule contains four atoms of iron. The ironatoms in the hemoglobin give red blood cells their red color. Theiron atoms bind reversibly with oxygen. Reversible binding meansthat at the appropriate time, the oxygen can be released elsewherein the body and be taken up by the cells that need it.

Figure 15 summarizes the path of oxygen and carbon dioxidethrough the body:

Oxygen from the outside air reaches the lungs.

The oxygen diffuses from the alveoli to the pulmonary capillar-ies. At the high oxygen levels that occur in the blood within thelungs, most hemoglobin molecules carry a full load of oxygen.

The oxygen-rich blood then travels to the heart. The heartpumps the blood to the tis-sues of the body.

Oxygen diffuses into the cellsfor use during aerobic respi-ration. In the tissues, oxygenlevels are lower. This causesthe hemoglobin to release itsoxygen.

In tissues, the presence ofcarbon dioxide produced bycellular respiration makes theblood more acidic and causesthe hemoglobin molecules toassume a different shape, onethat gives up oxygen more eas-ily. The carbon dioxide diffusesfrom the cells to the blood.

Most of the carbon dioxidetravels to the heart as bicar-bonate (HCO3

–) ions.

The heart pumps the blood tothe lungs. In the lungs, carbondioxide is released in itsgaseous form to the alveoli.

The carbon dioxide is expelled.

O2

O2CO2

CO2

CO2

CO2

CO2

HCO3–

HCO3–

HCO3–

O2

O2

O2

O2

O2

Cells

Systemicarteries

Systemicveins

Pulmonaryarteries

Pulmonaryvein

Heart

Alveoli

O2 diffusesinto blood.

O2 is inhaled.

Red blood cells carry O2.

CO2 diffuses to the blood.

CO2 is exhaled.

CO2 is releasedin its gaseousform to thealveoli.

O2 diffuses into cells.

Most CO2 travels in theblood as bicarbonateions (HCO3

–).

Figure 15 O2 and CO2transport in the blood.Hemoglobin molecules insidered blood cells transport oxygen, while most carbondioxide is transported as bicar-bonate ions in the plasma.

888

Student Edition TAKS Obj 1 Bio/IPC 2A, 2B, 2C TAKS Obj 2 Bio 4B TAKS Obj 2 Bio 10A TAKS Obj 2 Bio 10B TEKS Bio 4B, 10A, 10B, 11ATEKS Bio/IPC 2A, 2B, 2C

Teacher Edition TAKS Obj 1 Bio/IPC 2A, 2B, C TAKS Obj 2 Bio 10B TAKS Obj 4 IPC 7D, 8A, 9B TEKS Bio 10B, 11A, 11B, 11CTEKS Bio/IPC 2A, 2B, 2C, 3CTEKS IPC 7C, 7D, 9B

pp. 888–889IPC Benchmark Fact

Have students research the hemoglobin molecule anddetermine whether the iron atoms have a valence of2� or 3� and how these different values affect thenumber of oxygen molecules that bind to the ironatoms. TAKS 4 IPC 7D (grade 11 only)

Teaching TipRespiratory Control Center Tellstudents that changes in blood gasand pH levels trigger changes in therate of respiration. Chemoreceptorsin the cartotid arteries (on eitherside of the neck) and in the aortadetect CO2 and O2 concentrationin the blood as well as blood pH.When these receptors detect highCO2 levels, low O2 levels, or lowblood pH, they send signals to therespiratory control center locatedin the medulla oblongata of thebrain. In addition, other receptorsthat detect high CO2 levels and lowpH in the cerebrospinal fluid of thebrain send signals to the respiratorycontrol center. When the respira-tory control center receives thesesignals, it sends signals to the mus-cles involved in breathing. Themuscles contract more frequently,which results in an increase in therespiration rate. This, in turn, low-ers CO2 levels, raises O2 levels, andraises blood pH. TAKS 2 Bio 10B (grade 11 only); Bio 11A, 11B

Chapter 38 • Circulatory and Respiratory System 889

Modeling the Roleof Bicarbonate inHomeostasisSkills AcquiredInferring, analyzing

Teacher’s NotesCarefully review the chemicalequations on this page.

Answers to Analysis

1. A becomes acidic; B becomesbasic.

2. sodium bicarbonate, H2CO3-3. H2O + CO2 �� H2CO3

4. It buffered the carbonic acid.5. Most of the CO2 in the blood

travels as bicarbonate ions.results primarily from the action of sunlighton hydrocarbons and nitrogen oxides emittedduring fuel combustion. Particulate matter airpollution is a mixture of substances thatincludes particles, dust, and aerosols. Principalsources of nitrogen dioxide are automobilesand fuel combustion by electric utilities. Sulfurdioxide is formed when fuel containing sulfur(mainly coal and oil) is burned. Major sourcesof sulfur dioxide are electric utilities andindustrial fuel combustion. Bio 11C

Nearly 335,000 Americans die each year fromlung disease, which is the third leading causeof death in the United States. During the lastten years, the death rate for lung disease hasrisen faster than that of any of the top fivecauses of death.Air pollution contributes to lung disease,including respiratory tract infections, asthma,emphysema, and lung cancer. The major types of air pollution include excess ozone,particulate matter, nitrogen dioxide, and sul-fur dioxide. Excess ozone in the atmosphere

ENVIRONMENTAL SCIENCEENVIRONMENTAL SCIENCECONNECTIONCONNECTION

Carbon Dioxide Transport At the same time that the red blood cells are unloading oxygen totissues, they are also taking in carbon dioxide from the tissues.Carbon dioxide is carried by the blood in three forms:

1. About 7 percent of CO2 is dissolved in the blood plasma.

2. About 23 percent of CO2 is attached to hemoglobin moleculesinside red blood cells.

3. The majority of CO2, 70 percent, is carried in the blood as bicar-bonate ions.

How is CO2 carried as bicarbonate ions? In the presence of a cer-tain enzyme, carbon dioxide combines with water to form carbonicacid, H2CO3. This is shown in the equation below. The carbonic acidthen breaks up to form a bicarbonate ion, HCO3

–, and a hydrogenion, H+:

H2O � CO2←→ H2CO3

←→ HCO3– � H+

Thus, most of the CO2 travels in the blood as bicarbonate ions. Thehydrogen ions make the blood more acidic. When the blood reachesthe lungs, the series of reactions is reversed:

HCO3– � H+ ←→ H2CO3

←→ H2O � CO2

A bicarbonate ion combines with a hydrogen ion to form carbonicacid, which in turn forms CO2 and water. The CO2 diffuses out ofthe capillaries into the alveoli and is exhaled into the atmosphere.

Modeling the Role of Bicarbonate in HomeostasisYou can use pH indicator paper, water, and baking soda to model the role of bicarbonate ions in maintaining blood pH levels in the presence of carbon dioxide.

Materials

two 250 mL beakers, 250 mL distilled water, 2.8 g baking soda,glass stirring rod, 4 strips of wide-range pH paper, 2 drinking straws

Procedure

1. Label one beaker A andanother B. Fill each beakerhalfway with distilled water.

2. Add 1.4 g of baking soda tobeaker B, and stir well.

3. Test and record the pH of thecontents of each beaker.

4. Gently blow through a straw,into the water in beaker A.

Test and record the pH of theresulting solution.

5. Repeat step 4 for beaker B.

Analysis

1. Describe what happened tothe pH in the two beakersduring the experiment.

2. State the chemical name forbaking soda.

3. Propose the chemical reac-tion that might have caused achange in pH in beaker A.

4. Summarize the effect thebaking soda had on the pHof the solution in beaker Bafter blowing.

5. Critical ThinkingApplying InformationRelate what happened inbeaker B to what occurs inthe bloodstream.

2A 2B 2C 11A

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TAKS 1

TAKS 1 Bio/IPC 2A, 2B, 2C; Bio 11A

IPC BenchmarkFact

Remind students that the chemicalchange of H2CO3 into HCO3

� � H� (andvice versa) is an example of an oxida-tion/reduction reaction, that is, electronsare shifted from one substance to anoth-er. Have advanced students write thehalf reactions for this chemical reactionand identify the substances oxidized andreduced. TAKS 4 IPC 8A

ReteachingDraw a simplified version ofFigure 15 on the board. Have stu-dents close their books, and askvolunteers to draw arrows showingthe directions of circulation and gasexchange. Have other volunteersannotate the diagram with briefstatements that describe key events.

Visual

Quiz1. The ________ in the lungs are the

sites of oxygen uptake into theblood. (alveoli)

2.The muscles involved in breath-ing are the muscles of the________ and the ________ . (rib cage, diaphragm)

3. Oxygen is carried in the bloodbound to ________ inside________ cells. (hemoglobin, red blood)

4. Carbon dioxide is carried in theblood primarily in the form of________ .(bicarbonate ions)

AlternativeAssessmentHave students draw pictures oflungs during inhalation and exhala-tion. Students should use labeledarrows to show the direction ofdiaphragm and rib muscle movementand oxygen and carbon dioxidemovement. TAKS 2 Bio 10B (grade 11 only); Bio 3E

GENERAL


GENERAL

TAKS 2 Bio 10B (grade 11 only); Bio 3ELS

CloseClose


1. mouth, trachea, bronchi, bronchioles, andalveoli

2. The diaphragm moves down; the ribs move upand out.

3. Levels of oxygen and carbon dioxide in theblood regulate the rate of breathing. Increasedblood carbon dioxide concentration triggersthe brain to send a message to the diaphragmand rib muscles that speeds up the rate ofbreathing.

4. Seventy percent of the carbon dioxide in theblood is carried as bicarbonate ions.TAKS 2 Bio 10A, 10B (grade 11 only)

TAKS 2 Bio 10A


TAKS 2 Bio 10A, 10B (grade 11 only)5. Yes, any physical effort increases the oxygen

needed and energy required to breathe.

6. A. Incorrect. The function of thelarynx is to produce sound. B. Correct. Thealveoli are air sacs where gas exchange takesplace. C. Incorrect. The trachea transports airto the bronchi. D. Incorrect. The bronchi aretubes that lead to the lungs. TAKS 2 Bio 10A

TAKS 2 Bio 10A, 10B (grade 11 only); Bio 11C


Respiratory Diseases Respiratory diseases affect millions of Americans. A chronic pul-monary—or lung—disease is one for which there is no cure.

Asthma Asthma (AZ muh) is a chronic condition in which the bronchiolesof the lungs become inflamed, because of their sensitivity to certainstimuli in the air. The bronchial walls tighten and extra mucus isproduced, causing the airways to narrow. In severe asthma attacks,the alveoli may swell enough to rupture. Stressful situations andstrenuous exercise may trigger an asthma attack. Left untreated,asthma can be deadly. Fortunately, prescribed inhalant medicinesmay help to stop an asthma attack by expanding the bronchioles.People of all ages can have asthma.

Emphysema Emphysema (ehm fuh SEE muh) is a chronic pulmonary diseaseresulting from a chemical imbalance that destroys elastic fibers inthe lungs. Normally, these elastic fibers allow the lungs to expandand contract. Emphysema begins with the destruction of alveoli. Dam-age to the alveoli is irreversible and results in constant fatigue andbreathlessness. Severely affected individuals must breathe from tanksof oxygen in order to live. Smoking is the cause of up to 90 percent ofemphysema cases. Emphysema claims millions of lives annually.

Lung Cancer Lung cancer is one of the leading causes of death in the world today.As shown in Figure 16, cancer is a disease characterized by abnormalcell growth. In the United States alone, about 28 percent—155,000—of all cancer deaths each year are attributed to lung cancer. Oncecancer is detected, the affected lung is sometimes removed surgically.Even with such drastic measures, lung cancer usually is not curable.About 15 percent of lung cancer victims live more than 5 years afterdiagnosis.

Sequence the path a breath of air follows throughthe respiratory system. (Begin with air that entersthrough the nose or mouth.) 10A 10B

State the direction in which the diaphragm andrib muscles move before inhalation. 10A 10B

Name the main factor that regulates the rate ofbreathing. 10A

Evaluate the role that bicarbonate plays intransporting carbon dioxide in the blood.

Critical Thinking Justifying ConclusionsWould a person with emphysema have troubleclimbing stairs? Explain. 10A 10B 11C

Gases are exchanged betweenthe blood and inhaled air in the 10A

A larynx C tracheaB alveoli D bronchi


Section 3 Review

10A 10B

Figure 16 Healthy lungsand cancerous lungs. Thetop photo shows a healthylung. The bottom photo shows a cancerous lung which contains cells that divideuncontrollably.

890

Student Edition TAKS Obj 2 Bio 10A TAKS Obj 2 Bio 10B TEKS Bio 10A, 10B, 11C

Teacher Edition TAKS Obj 2 Bio 10ATAKS Obj 2 Bio 10BTEKS Bio 3E, 10A, 10B, 11C

pp. 890–891

AlternativeAssessmentHave students make a board gamewith questions about normal andabnormal function of the circula-tory and respiratory systems.TAKS 2 Bio 10B (grade 11 only)

GENERAL


• Science Skills Worksheet• Critical Thinking Worksheet• Test Prep Pretest• Chapter Test GENERAL

GENERAL

GENERAL

Chapter Resource File

such as

largest are

blood vessels

capillaries veins

venae cavae

largest is

aorta

lymphatic system

Circulatory system

is composed of

arteries

has

atria ventriclessystemic

circulationpulmonarycirculation

heart

regulates

Answer to Concept Map

The following is one possible answer to Performance Zone item 15.

Key Concepts

Study CHAPTER HIGHLIGHTS

ZONEKey Terms

Section 1cardiovascular system (872) artery (873)capillary (873)vein (873)valve (874)lymphatic system (875)plasma (876)red blood cell (876)anemia (877)white blood cell (877)platelet (877)ABO blood group system (878)Rh factor (879)

Section 2atrium (881)ventricle (881)vena cava (881)aorta (882)coronary artery (882)sinoatrial node (882)blood pressure (882)pulse (883)heart attack (884)stroke (884)

Section 3pharynx (886)larynx (886)trachea (886)bronchus (886)alveolus (886)diaphragm (886)

The Circulatory System

● The human cardiovascular system is made up of blood vessels, blood, and the heart, which together function to transport materials, remove wastes, and distribute heat.

● Arteries carry blood away from the heart. Materials areexchanged at the capillaries. Veins contain valves and carryblood back to the heart. Fluids not returned to the capillariesare picked up by lymphatic vessels.

● Blood consists of plasma (water, metabolites, wastes, salts,and proteins), red blood cells, white blood cells, and platelets.

● Blood types are defined by the presence or absence of complex carbohydrates on the surface of red blood cells.

The Heart

● The right side of the heart receives oxygen-poor blood fromthe body and circulates it to the lungs. In the lungs, gasesare exchanged. The left side of the heart receives oxygenatedblood from the lungs and circulates it to the rest of the body.

● Atria receive blood entering the heart. Ventricles pumpblood away from the heart.

● Contraction of the heart is initiated by the sinoatrial node.The health of the cardiovascular system can be monitored bymeasuring blood pressure, electrical impulses, and pulse rate.

● Blockages in blood vessels can lead to heart attacks or strokes.

The Respiratory System

● A series of tubes and bunched air sacs (alveoli) take in oxygen and remove carbon dioxide.

● Breathing is caused by pressure changes within the chest cavity.● The concentration of carbon dioxide in the blood is the most

critical factor affecting a person’s breathing rate and depth. ● Oxygen is transported to tissues by combining with hemo-

globin molecules inside red blood cells. Most carbon dioxideis transported to the lungs as bicarbonate ions.

● Asthma, emphysema, and lung cancer limit lung function.

3

2

1

891

ANSWERS

Using Key Terms

1. b2. b3. c4. b5. a. Plasma is the liquid part of the

blood; lymph is fluid thatleaks out of blood vessels andinto surrounding tissues.

b. Blood pressure is the pressureexerted by blood as it movesthrough the blood vessels.Blood pressure is expressed inmm Hg. Pulse is a series ofpressure waves within anartery caused by a contractionof the left ventricle. Pulse is anindicator of the number oftimes the heart beats in aminute.

c. A heart attack occurs when anarea of the heart muscle isstarved of oxygen and stopsworking; it is usually causedby a blocked blood vessel inthe heart. A stroke is a suddenattack of weakness or paraly-sis that occurs when an area ofthe brain is starved of oxygenafter blood flow to that part is interrupted.

Understanding Key Ideas

6. b7. c8. a9. c

10. b11. c12. d TAKS 2 Bio 10A; Bio 11C

TAKS 2 Bio 10A, 10B (grade 11 only)TAKS 2 Bio 10ATAKS 2 Bio 10ATAKS 2 Bio 10ATAKS 2 Bio 10ATAKS 2 Bio 10A

TAKS 1 Bio/IPC 2C; TAKS 2 Bio 10ATAKS 2 Bio 10A; Bio 11CTAKS 2 Bio 10ATAKS 2 Bio 10A, 10B (grade 11 only)

13. Answers will vary but may include any eventthat has a significant aerobic component,such as running, cycling, or swimming.

14. Thinner blood reduces the chances of clot formation.

15. The answer to the concept map is found atthe bottom of the previous page.TAKS 1 Bio/IPC 2C; Bio 3E

TAKS 2 Bio 10A; Bio 11C

Bio 11CSection Questions

1 4, 5, 6, 7, 13, 15, 16, 17, 19, 212 1, 2, 8, 11, 12, 14, 203 3, 9, 10, 18, 22

Assignment Guide


CHAPTER 38

Using Key Terms1. The chamber of the heart that sends blood

to the lungs is the a. left ventricle. c. left atrium.b. right ventricle. d. right atrium.

2. The pacemaker of the heart is the a. left ventricle. c. coronary sinus.b. sinoatrial node. d. inferior vena cava.

3. A disease in which the elastic fibers in thealveoli are destroyed is called a. atherosclerosis. c. emphysema.b. arteriosclerosis. d. asthma.

4. The layer labeled A is a. connective tissue. c. endothelium.b. smooth muscle. d. a valve.

5. For each pair of terms, explain thedifferences in their meanings: a. plasma, lymphb. blood pressure, pulsec. heart attack, stroke

Understanding Key Ideas6. Lymphatic vessels

a. transport blood.b. return fluid to the blood.c. produce antibodies.d. control blood clotting.

7. What type of blood contains A antibodies(but not B antibodies) in the plasma andlacks Rh antigens? a. AB negativeb. A positivec. B negatived. O positive

8. Blood in the pulmonary veins is a. oxygen-rich. c. oxygen-poor.b. iron-poor. d. calcium-rich.

9. The diaphragm contracts and the pressurein the chest cavity decreases during a. bronchitis. c. inhalation.b. exhalation. d. asthma attacks.

10. Breathing rate will automatically increasewhen a. blood pH is high.b. the amount of carbon dioxide in the

blood increases.c. blood acidity decreases.d. hemoglobin is unloaded.

11. Which organ receives the richest oxygensupply from blood returning from thelungs? a. stomach c. heartb. brain d. kidney

12. Which is not a factor that contributes to chronic coronary disease? a. a diet rich in fatb. unmanaged stress c. cigarette smokingd. vigorous exercise

13. For what types of athleticevents would blood doping most likelyincrease an athlete’s performance? Explainyour reasoning.

14. One of the effects ofaspirin is that it thins the blood. Why isaspirin sometimes prescribed for people atrisk for heart attack?

15. Concept Mapping Make a conceptmap that outlines the path of bloodthrough the body. Try to include the fol-lowing terms in your map: artery, capillary,vein, lymphatic system, pulmonary circula-tion, systemic circulation, atrium, ventricle,aorta, and vena cava.

PerformanceZONE

CHAPTER REVIEW

A

10A 10B

10A 11C

2C 10A

10A

10A

10A

10A

10A

10A

10A 10B

10A 11C

11C

10A 11C

2C 3E

892

Review and AssessTAKS Obj 1 Bio/IPC 2CTAKS Obj 2 Bio 10A, 10BTEKS Bio 3D, 3E, 3F, 10A, 10B, 11CTEKS Bio/IPC 2C

pp. 892–893

Critical Thinking

16. Clotting ability is most likelydiminished because platelets willnot stick as readily.

17. Cell surface markers called anti-gens exist on blood cells. Bloodtypes are named for the antigenspresent.

18. It will decrease because the run-ner will not get as much oxygenas obtained at sea level.

19. Constriction of blood vessels con-serves heat. Dilation of bloodvessels increases heat dissipation.

Alternative Assessment

20. Answers will vary but shouldinclude fish, fresh fruits, vegeta-bles, and foods low in saturatedfat.

21. Answers will vary. Dr. Drewfound a way to keep bloodplasma fresh. He also started thefirst blood bank.

22. Respiratory therapists treatpatients who have breathing diffi-culties. Respiratory therapists userespirators and oxygen tents.They develop treatment programsfor long-term care, and they oper-ate and maintain oxygen deliveryequipment. Most attend twoyears of college with an emphasison math and science courses.Respiratory therapists must beprofessionally certified. Many areemployed by hospitals or physi-cians. The growth prospects ofthe field are excellent. Startingsalary will vary by region. Bio 3D

Bio 3F



TAKS 2 Bio 10A, 10B (grade 11 only);Bio 11C



1. A. Incorrect. This is the blood pressure associ-ated with about 10 g per day of salt intake.B. Incorrect. This is the blood pressure associ-ated with about 16 g per day of salt intake.C. Incorrect. This is the blood pressure associ-ated with about 20 g per day of salt intake.D. Correct. Consumption of 23 g of salt perday is correlated with a blood pressure of150 mm Hg.

2. F. Incorrect. 16 g is a better choice because 4 gis not an excessive amount. G. Correct. Ablood pressure of 130 mm Hg is at the highend of normal and is correlated to 16 g per dayof salt. H. Incorrect. Daily consumption of 19 gof salt is associated with a blood pressure of

TAKS 1 Bio/IPC 2C; TAKS 2 Bio 10A

about 140 mm Hg, above normal. J. Incorrect.Daily consumption of 27 g of salt is associatedwith a blood pressure of about 160 mm Hg,above normal.

3. A. Correct. There seems to be a direct relation-ship between salt intake and blood pressure.B. Incorrect. Increased systolic blood pressuredoes not itself increase a person’s appetite forsalt. C. Incorrect. Consuming more salt makeshypertension worse. D. Incorrect. A daily saltintake of 10 g or less does not increase bloodpressure above normal nor cause damage inany other way to the cardiovascular system.TAKS 1 Bio/IPC 2C; TAKS 2 Bio 10A, 10B (grade 11 only); Bio 11C

TAKS 1 Bio/IPC 2C; TAKS 2 Bio 10A

The chart below shows the relationshipbetween daily salt intake and blood pressure inhumans. Use the chart and your knowledge ofscience to answer questions 1–3.

1. A person who consumes 23 g of salt per dayis likely to have a systolic pressure of about A 120 mm Hg. C 140 mm Hg.B 130 mm Hg. D 150 mm Hg.

2. People with a normal systolic pressure likely have a daily salt intake that does not exceed F 4 g. H 19 g.G 16 g. J 27 g.

3. What conclusion can be drawn from the chart? A Increasing one’s salt intake leads

to an increased systolic pressure. B Raising one’s systolic pressure leads

to a greater appetite for salt.C A person can control hypertension by

consuming more salt.D A daily salt intake of 10 g or less is

associated with a risk to health.

2C 10A 10B 11C

Test

Critical Thinking16. Forming Reasoned Opinions The frequency

of blood clots and heart attacks is muchlower among the Inuit, the nomadichunters of the North American Arctic, thanit is among other North Americans. This dif-ference is credited to fish oils in the Inuit dietthat cause blood platelets to be more slippery.How might slippery platelets affect the clot-ting ability of the Inuit’s blood?

17. Interpreting Information What role do cellsurface markers play in blood typing?

18. Evaluating Results As altitude increases,the atmosphere becomes thinner. When arunner who trained at sea level competes ata location 500 m above sea level, how willhis or her performance compare with his orher training performance?

19. Inferring Function How is body tempera-ture regulated by blood vessel diameter?

Alternative Assessment20. Finding Information Use the media center

or Internet resources to find out whichfoods are recommended as foods that prevent heart disease.

21. Multicultural Perspective Dr. Charles Drew was an African-American physician.Write a report that discusses the life of Dr. Drew and his many accomplishments.How did his work with blood help savemany lives?

22. Career Connection Respiratory Therapist Research the field of respiratorytherapy, and write a report on your find-ings. Your report should include a jobdescription, training required, kinds ofemployers, growth prospects, and starting salary.


Scan the answer set for words such as “never” and “always.” Such words often are used instatements that are incorrect because they are too general.

Sys

tolic

pre

ssure

(mm

Hg)

0

110

120

130

140

160

170

150

10 20 30

Daily salt intake (g)

10A 11C

10A 10B

10A 10B 11C

10A 10B

10A 11C

3F

3D

2C 10A

2C 10A

893


Documents

Section 1 The Circulatory System - · PDF filethe circulatory system, and write them on the board. ... 872 Chapter 38 • Circulatory and Respiratory Systems Transparencies TT Bellringer