UNIT 3A: MAINTAINING DYNAMIC EQUILIBRIUM IHomeostasis & Circulatory System

Name: ____________________Slot: ______

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Homeostasis- The process of maintaining a relatively constant internal physiologicalenvironment despite changing external conditions.

Optimal body conditions for HomeostasisThe body works best when specific body constants are maintained such as:

- body temperature of 37 0C- blood pH of 7.4- blood pressure 120/80 mmHg- 0.1% blood sugar

These constants can vary among individuals:- different metabolic rates of individuals affect body temperature- different situations or demands on body (eg) exercise- blood pressure difference between adults and children

Cells in the human body must maintain a constant environment in order to survive. Thisis accomplished because interstitial fluid surrounds the cell.

Interstitial Fluid- A fluid that surrounds cells of the human body.- The concentration and pH remains relatively constant in order for cells to remain healthy.

This maintenance of a constant internal environment (homeostasis) is an example of dynamic equilibrium.

Dynamic Equilibrium- a state of balance achieved within an environment as the result of internal control mechanisms that continuously oppose outside forces that tend to change that environment.

Q. How do humans maintain Homeostasis?

A. Feedback MechanismsHumans have two types of feedback mechanisms:

a. Negative Feedback mechanism

b. Positive Feedback mechanism

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Negative Feedback Mechanism- A process that detects & reverses deviations from normal body constants.- involves three parts:

1. receptor2. integrator3. effector

Sensory Receptor:- Found throughout every body organ & tissue.- Receptors send nerve impulses (stimuli) to the brain in response toenvironmental information.- Sensory receptors monitor the body’s internal conditions.

Integrator:- located in the brain (hypothalamus).- Sends messages to the effectors.

Effector:- These are structures that carry out changes in the body.- These are muscles and glands.- Messages can be transmitted by nervous system or by chemical messengers known as hormones.

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Positive Feedback Mechanism- A mechanism that acts to increase the strength of a stimulus.- Positive feedback mechanisms pushes a system away from balance

andstability.- These are usually associated with disease or change

- Example: high blood pressure

Temperature Regulation – An example of Negative Feedback

Homeotherm- An organism that maintains a relatively constant body temperature.- Example: mammals (humans) & birds

Poikilotherm- An organism whose body temperature fluctuates depending on temperature of the animal’s environment.

- Example: cold blooded animals

How is body temperature maintained in Humans?

The human body generates heat as a by-product of metabolic processes & uses several different mechanisms to control the rate at which heat is lost through the skin.

The human body uses TWO mechanisms by which it controls body temperature.

a. Behavioural mechanismsThese are changes in behaviour that a person in order to control temperature

(e.g.) put a sweater on when cold. Take off a sweater when warm.

b. Physiological mechanismsThese are changes in the body that help to control temperature.

(eg) circulatory system

Types of Physiological Mechanisms in humans

1. VasoconstrictionBlood vessels constrict in diameter thereby reducing the amount of bloodthat travels through. This helps to conserve heat and raise temperature.

2. Vasodilation

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Blood vessels increase in diameter thereby increasing the flow of bloodthrough. This helps to release heat and lower temperature.

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The Human Circulatory System

The circulatory system is the system that transports materials around the body to and from the cells.

Question? Why do humans need a circulatory system whereas bacteria and simple organisms do not?

Answer:Because the cells of a complex organism such as a human have manycells that are far from the outside environment where nutrients wouldcome from. The system brings the materials to the cells that would notnormally receive them.

Humans have a closed circulatory system: This means that the blood is alwayscontained in tubes and vessels.

The human circulatory system is composed of the following:

1. Blood Vessels2. Heart3. Blood______________________________________________________________________________

BLOOD VESSELSHumans have three types of blood vessels. They are:

a. ArteriesStructure:

Thick, elastic Contain layers of connective, and smooth muscle tissues DO NOT CONTAIN VALVES

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Function: Carry Blood AWAY from the heart.

Arteries divide to form very small arteries called arterioles.

b. VeinsStructure:

Thin and slightly elastic. Contain VALVES for one way flow of blood.

Function: return blood TO the heart

Veins divide to become venules.

Medical Alert: Varicose VeinsThis is a condition where the valves in the veins of a personare not working properly and blood seeps back into the veincausing the vein to become stretched and lose their elasticity.

Result: Sagging veins and lack of blood flow to the heart.

c. CapillariesStructure:

Microscopic blood vessels that connect arterioles and venules. Thin walled and narrow Blood cells pass through them in single file

Function: Allows material and gas exchange between the body cells and theblood.

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THE HEART

Structure: A four chambered muscular organ located in the chest cavity of a

human. Made of Cardiac muscle. It is Covered by a Pericardium that protects it.

o Pericardium: A tough membrane that surrounds the heart.

Function: Pump blood around the body supplying the cells with nutrients and removing wastes (CO2) from the cells.

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Functions of Heart Structures

1. Inferior/Superior Vena Cava: Returns deoxygenated blood to the right atrium from the body.

2. Right Atrium: Thin walled chamber of the heart that receivesdeoxygenated blood from the body.

3. Tricuspid valve: Controls the flow of blood entering the right ventricle fromthe right atrium.

4. Right Ventricle: Muscular chamber that pumps blood TO the lungs.

5. Semilunar Valves: Valves that control the flow of blood out of the heart.

6. Pulmonary Arteries: Arteries that carry blood TO the lungs.

7. Pulmonary Veins: Veins that bring blood to the heart from the lungs.

8. Left Atrium: Thin walled chamber that receives oxygenated blood fromthe lungs.

9. Left Ventricle: Thick walled chamber that pumps blood out of the heart andto the body.

10. Aorta: Large artery that carries blood away from the heart and to allparts of the body.

11. Septum: A wall of muscle that separates the left side of the heart fromthe right side. This prevents the mixing of oxygenated and deoxygenated blood.

12. Chordae Tendonae: Control the opening and closing of the Tricuspid andBicuspid (Mitral) valves.

13. Bicuspid Valve: A valve that controls the flow of blood from the left atrium to the left ventricle.

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Blood Flow through the HeartDeoxygenated blood from the body enters the right Atrium via the Inferior and Superior Vena Cava (e). Here the blood is passed through the tricuspid valve to the right ventricle. The right ventricle contracts and forces blood up through the Semilunar valves and out through the left and right pulmonary arteries. This brings blood to the lungs to be oxygenated.

Oxygenated blood from the lungs returns to the heart via the left and right pulmonary veins to the left atrium. The blood is passed to the left ventricle through the bicuspid valve. The left ventricle contracts and pushes blood through the Semilunar valves and out through the aorta to the body.

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THE HEARTBEAT CYCLEThe human heartbeat occurs in two main stages.These two stages are: a. Diastole

b. Systole

Diastole The stage where the heart is Relaxing

During this stage the A-V valves (bicuspid, tricuspid) are open and the semilunar valves close. The ventricles fill with blood.

Systole The stage where the heart is Contracting

During this stage the ventricles contract. This causes the A-V valves to close and the semilunar valves to open. Blood is forced out through the semilunar valves to the lungs and body.

The “LubDub” sound of the HeartbeatThe “LubDub” sound of the heartbeat is caused by the closing of the heart’s valves.

Lub Sound -- caused by the closing of the A-V valves (tricuspid, bicuspid).

Dub Sound -- caused by the closing of the semilunar valves.

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CONTROL OF THE HEARTBEATThe heart is caused to beat regularly by a structure called the Sinoatrial Node (S – A node) or the PACEMAKER.

How it happensAn electrical impulse from the brain is received by the S-A node(pacemaker) in the right atrium. The SA node sends a signal to the A-V node (atrioventricular node) in the right ventricle. This electrical impulse causes the heart (ventricles) to contract.

The pacemaker controls the heartbeat for a human from the time they are born until they die or the pacemaker gives out.

Q. What happens if the pacemaker gives out?

A. The person’s heart will stop beating because the ventricles are not receivingelectrical impulses causing them to contract.A person whose pacemaker gives out can get an artificial one inserted into their chest.

CONTROL OF THE HEART RATEThe heart rate (speed) at which the heart beats is controlled by two nerves.

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Medulla Oblongata (Sometimes called the Cardioaccelerator nerve):Nerve in the brain that causes the heart to speed up when needed.

Vagus nerve: Nerve in the brain that causes the heart to slow down whenneeded.

The medulla sends a message to the SA node to cause an impulse to be sent to the AV node causing the heart to contract more or less in an attempt to set the heart rate.

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BLOOD PRESSUREBlood Pressure: A measure of the pressure blood exerts on the walls of blood vessels.

Q. How is blood pressure measured?

A. Blood pressure is measured using a blood pressure cuff orSphygmomanometer.

It measures the pressure in an artery while the heart is contracting (systolicpressure) and the pressure while the heart is resting (diastolic pressure). Asimple fraction is calculated using the following formula:

Blood Pressure = Systolic PressureDiastolic Pressure

For example: A person with a pressure 120/80 means that the person has a

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pressure of 120 while the heart is contracting and 80 when the heart is relaxing.

Normal blood pressure is different for each person but is usually around 120/80. *In the medical field, this number changes!

DIVISIONS OF CIRCULATIONThere are two types of circulation that happen in the human organism.

1. Pulmonary Circulation2. Systemic circulation______________________________________________________________________________

1. PULMONARY CIRCULATION

This is circulation of blood from the heart and to the lungs and vice versa.

This type of circulation adds oxygen and removes carbon dioxide from theblood.

2. SYSTEMIC CIRCULATION

This is circulation of blood between the heart and the body.

This type of circulation brings blood to the cells and from the cells.

Systemic circulation has three subdivisions. They are:A. Coronary CirculationB. Hepatic-portal circulationC. Renal circulation

A. Coronary circulation is circulation that supplies blood and nutrients directlyto the heart muscle.

B. Hepatic - portal circulation is circulation that carries nutrients and bloodfrom the digestive system to the liver to maintain glucose levels in thebody.

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C. Renal Circulation is circulation that carries blood to and from the kidneysso that nitrogenous wastes may be removed from the blood andexcreted by the kidneys.

THE LYMPHATIC SYSTEMThis is the part of the circulatory system that returns excess fluids to the blood from the body.

Parts of the Lymphatic System1. Lymph2. Lymph Nodes3. Intercellular Fluid4. Spleen

1. LymphThis is the fluid that is found within the lymphatic system. It contains water,proteins and intercellular fluid.

2. Lymph NodesThese are small glands at various locations in the body that filter foreign matter from the lymph. Foreign matter usually means bacteria, cancer cells and other disease causing organisms.

The Lymph nodes also contain White Blood Cells that fight off infection.

If you have swollen lymph nodes then this is an indication that you may

have an infection.

3. Intercellular FluidThis is the fluid that is usually squeezed out of a capillary during normal cellactivities. It helps move materials between the cells and the capillaries.

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It usually contains salt, water, proteins and nutrients.

4. SpleenAn organ near the stomach that contains lymph tissue.

Function: Filter out bacteria and worn out RBC’s from the blood.

BLOODBLOOD: Fluid found in the circulatory system of humans that carries nutrients and Oxygen to the cells and carries wastes ( carbon dioxide) away from thecells.

Helps to control and regulate body temperature as well.

COMPONENTS OF BLOOD

There are three components to blood:A. PlasmaB. Blood CellsC. Platelets

______________________________________________________________________________

A. Plasma

The liquid part of blood.

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Makes up 55% of the volume of blood.92% water and 7% proteins, 1 % dissolved solutes.

Plasma has three proteins in it.i) Albumins: Keeps water from leaving the blood.ii) Fibrinogen: Used for blood clotting.iii) Globulins: Transport proteins around the body. Some are

antibodies.

Antibody: Proteins that binds to and helps destroy a foreign substancein the body.______________________________________________________________________________B. Blood CellsTwo types:

Red Blood Cells (RBC’s) White Blood Cells (WBC’s)

i) Red Blood Cells --- called Erythrocytes Human blood contains about 30 trillion RBC’s. DO NOT contain Nuclei (NONNUCLEATED) Created by the bone marrow - stem cells. Live about 120 days Double concave shaped Contain a protein called hemoglobin. Worn out RBC’s are removed by the liver and spleen.

Hemoglobin:A protein found in the blood that is made up of IRON. It carries oxygen to the cells and removes CO2

Composed of an Alpha and Beta Chain with 2 Heme (Iron) groups on each chain. The Heme groups bind to and attach Oxygen and CO2

Function of RBC’s: Transport oxygen to cells from the lungs.Transport carbon dioxide from the cells to the lungs.

______________________________________________________________________

ii) White Blood Cells – called Leukocytes Larger than RBC’s Have a nucleus Less numerous than RBC’s Can move on their own

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FUNCTION OF WBC’S: Fight foreign invaders and Infections.

Types of White Blood Cells

a) MacrophagesPhagocytic cells that protect the body by engulfing anddigesting foreign invaders (pathogens).

b) LymphocytesNon – phagocytic blood cells that produce antibodies.Two types: T Cells and B Cells

____________________________________________________

C. Platelets Small pieces of cells found in the blood. NO Nuclei Live about 7 days.

FUNCTION OF PLATELETS: Blood Clotting Process.

THE BLOOD CLOTTING PROCESSBlood Clotting is actually a complicated chemical process. This is how it works.

When a blood vessel is ruptured the following happens:

Step 1:Platelets rush to the area. They release an enzyme called Thromboplastin.

Step 2:Thromboplastin causes prothrombin (a protein) to be converted in thrombin(enzyme).

ThromboplastinProthrombin ---------------------------------------------> Thrombin

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Step 3:Thrombin causes fibrinogen (found in blood plasma) to be changed into fibrin.

ThrombinFibrinogen ---------------------------------------------------> Fibrin

Step 4:Fibrin forms a net of fibres over the cut and traps red blood cells and plateletsand forms a blood clot.

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Circulatory System Disorders

1. Hypertension High Blood Pressure

Causes: diet, stress, inactivity

Effects on body: Leads to heart disease and possible failure

2. Arteriosclerosis Hardening of the Arteries

Causes: Diet – High in Cholesterol (LDL) and Fats.

Effect on body: Causes arteries to become inelastic which can reduce the amount of blood flow in them. This can lead to a heart attack and/or stroke.

3. Atherosclerosis Narrowing of Arteries

Causes: Fatty deposits within the artery walls from poor diet/fat intake etc.

Effect on body: Narrowing of arteries reduces blood flow to heart and brain which may lead

to heart attack and/or stroke.

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4. Stroke: Loss of blood flow to brain tissue causing cell death.

Causes: Any one of the above and others

Effect on Body: loss of brain function and/or motor control (paralysis), death.

5. Coronary Blockage A blockage in the coronary arteries of the heart.

Causes: Diet, lack of exercise

Effect on Body: Heart attack, death.Treatments for Circulatory System Disorders

1. Thrombolytics

Thrombolytics are a class of drugs known as “Clot busting” drugs.

These drugs help to bust up blood clots that have formed. They help to clearblocked passageways etc.

Ex: Streptokinase or t - PA: A Clot busting drug that converts plasminogen to plasmin. Plasmin dissolves the clot.

2. Angioplasty

Procedure in which a small catheter (tube) with a balloon attached is inserted into an artery and then inflated. The inflation helps to stretch the artery in an attempt to increase blood flow to the heart.

Sometimes a Stent (small mesh netting) is put in place to keep the artery openafter the balloon is removed

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3. Coronary Bypass Surgery

Surgery in which a healthy blood vessel from another area in the body is used to create a new pathway around a blockage in a blood vessel near the heart,usually a coronary artery.

1. The _________________ is the name of the large blood vessel leaving the left ventricle of the heart.

2. The _____________ valve is the valve located between the left atrium and left ventricle of the heart.

3. _______________ are thick-walled and elastic blood vessels that carry blood away from the heart.

4. Blood entering the right atrium is said to be _______________________-.

5. Bulging of the veins in the arms and legs is a condition known as __________________.

6. The ________________________ is responsible for setting the pace of the heartbeat. It is located in the _____________ atrium.

7. The ______________ nerve is responsible for slowing the heart rate.

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8. The __________________________ returns deoxygenated blood to the right atrium from the lower part of the body.

9. The lining of the heart is called the _____________________.

10. An abnormally fast heartbeat is called _________________________.

11. The largest chamber of the heart is the _______________________.

12. The right ventricle contains _____________________ blood.

13. Microscopic blood vessels that supply cells with nutrients are called ________________.

14. Pressure in the blood vessels when the heart is contracting is called ________________ pressure.

15. The _________________________ carry blood from the right atrium to the lungs.

16. The lub sound of a heart beat is caused by ____________________________________.

17. The muscle that divides the left side of the heart from the right side is called the _________________________.

18. _______________________ are blood vessels containing valves.

19. Hardening of the arteries by fatty deposits is called _____________________________.

20. Circulation that feeds the heart muscle directly is called _________________________.

21. The __________________________ returns excess fluids to the blood from the body.

22. ___________________ is fluid containing water, proteins and intercellular fluids.

23. The _____________________________ are blood vessels returning blood to the left atrium from the lungs.

24. ___________________________ are glands containing white blood cells that help fight infection.

25. The _________________ is an organ that filters blood and removes worn out red blood cells from the body.

26. Blood pressure is measured using a device called a(n) ___________________________.

27. The stage of the heart beat when the heart is relaxing is called ____________________.

28. Circulation to and from the kidneys is called _________________________.

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29. A person gets a fright. Their heart rate suddenly increases. What structure is responsible for causing the heart rate to increase_________________________?

30. What do the numbers 120/80 mean in a blood pressure measurement? (Be specific).

31. Tendons within the heart that help keep the valves closed are called ______________________.

32. Electrical impulses sent from the SA node to the __________________ node within the ____________________ of the heart help set the heartbeat.

33. The left side of the heart contains only deoxygenated blood. True or False.

34. The upper chambers of the heart are called ____________________.

35. High blood pressure is referred to as __________________________.

36. ______________________ circulation is circulation of blood between the heartand the body.

HOMEOSTASIS:

1. Explain the meaning of the term homeostasis

2. Be able to describe the human body constantsa. Temp = 37 degree Celsiusb. Blood sugar = 100 mg/mLc. Blood pH = 7.4d. Blood Pressure = 12/80 mmHg

3. Explain the difference between a homeotherm and poikilotherm

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4. Explain the parts of a negative feedback mechanism a. Receptor (usually something associated with your senses)b. Integrator (usually in the brain – something that formulates a

response)c. Effector (usually a muscle or a gland – these carry out actions in

response to a change)

5. Explain how a negative feedback mechanism works.

6. Explain how negative feedback works to control temperature in humans.a. Vasoconstrictionb. Vasodilation

7. Explain the difference between a behavioural and physiological response to control temperature.

a. Behavioural = change in behavior i.e. put on or take off a sweaterb. Physiologica = body change i.e. vasoconstriction and vasodilation,

sweating and shivering

CIRCULATORY SYSTEM:

8. Explain why we need a circulatory (transport) system?

9. Describe the structure and function of:a. Veinsb. Arteriesc. Capillaries

10.Explain why each of the above structures are designed the way they are in relation to their role in blood circulation

11.Label and identify the main structures of the human heart and describe the role of each. The parts include:

a. Left and right atriumb. Left and right ventriclesc. Valves (bicuspid, tricuspid, and semilunar valves)d. Aorta

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e. Vena cava (superior and inferior)f. Pulmonary veing. Pulmonary arteryh. Septum

12.Trace the flow of blood through the heart and describe pulmonary and systemic pathways.

13.Explain the cardiac cyclea. Systole heart contractingb. Diastole heart relaxing

14.Be able to explain the lub dub sound of the heart Closing of AV and semilunar valves.

15.Explain how heart beat is set pacemaker (SA and AV node)

16.Explain how heart rate is set (cardioaccelerator and vagus nerves)

17.Explain how blood pressure is measured and what the values mean i.e. 120/80 mmHg

18. Understand the function of the Lymphatic System

19.Identify the main components of blood and explain the role of each. The components include:

a. Erythrocytes (red blood cells)i. Be able to explain how hemoglobin works to transport oxygen

and carbon dioxide. We have to know the role Iron plays here.b. Leukocytes (white blood cells)

i. Macrophages – engulfs foreign particles and kills themii. Lymphocytes – creates antibodies

c. Plateletsi. Involved in blood clotting

d. Plasma

20.Describe how each of the following circulatory diseases are caused.

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a. Hypertension (high blood pressure)b. Atherosclerosisc. Arteriosclerosisd. Coronary blockage

21.What are the following:a. Bypass surgeryb. Stentsc. Angioplastyd. Clot busting drugs i.e. tPa

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