Chapter 23Chapter 23

CIRCULATION: CIRCULATION:

CARDIOVASCULAR SYSTEMCARDIOVASCULAR SYSTEM

Functions of Cardiovascular System :Functions of Cardiovascular System : 1. Transport and exchange of gases: 1. Transport and exchange of gases: Carries Carries oxygenoxygen for aerobic respiration from lungs to for aerobic respiration from lungs to

tissues.tissues. Picks up Picks up carboncarbon dioxidedioxide from tissues and releases it in from tissues and releases it in

lungs.lungs.

2. Transport nutrients (from digestive system to cells)2. Transport nutrients (from digestive system to cells)

3. Transport hormones (from glands to target cells).3. Transport hormones (from glands to target cells).

4. Transport metabolic waste (to excretory organs)4. Transport metabolic waste (to excretory organs)

5. Defense against infection by pathogens.5. Defense against infection by pathogens.

6. Regulates water and ion balance.6. Regulates water and ion balance.

7. Distribution of metabolic heat and maintenance of body 7. Distribution of metabolic heat and maintenance of body temperature.temperature.

Diffusion Between Blood and Tissue Cells

Cardiovascular SystemCardiovascular SystemSystem of internal transportSystem of internal transport

Components: Components:

1. 1. Blood (Fluid connective tissue)Blood (Fluid connective tissue)

2.2. Heart (Pumping device) Heart (Pumping device)

3.3. System of blood vessels: System of blood vessels: Arteries and arteriolesArteries and arterioles Veins and venulesVeins and venules CapillariesCapillaries

Cardiovascular Systems of Fish and Mammal

Fish: Single circuitTwo chamber heart

Right side pumps O2 poor bloodLeft side pumps O2 rich blood

Mammal: Double circuitFour chamber heart

1. Blood1. Blood

Average Blood Volume:Average Blood Volume: 4 to 6 liters. 4 to 6 liters.

Blood composition:Blood composition:55% Plasma (fluid matrix of water, salts, proteins, etc.)55% Plasma (fluid matrix of water, salts, proteins, etc.)

45% Cellular elements:45% Cellular elements: Red Blood Cells (RBCs):Red Blood Cells (RBCs): 5-6 million RBCs/ml of blood. 5-6 million RBCs/ml of blood.

Contain hemoglobin which transport oxygen and COContain hemoglobin which transport oxygen and CO22..

White Blood Cells (WBCs):White Blood Cells (WBCs): 5,000-10,000 WBCs/ml of blood. 5,000-10,000 WBCs/ml of blood.

Play an essential role in immunity and defense. Include:Play an essential role in immunity and defense. Include:

• Lymphocytes:Lymphocytes: T cells and B cells T cells and B cells

• MacrophagesMacrophages (phagocytes) (phagocytes)

• Granulocytes:Granulocytes: Neutrophils, basophils, and eosinophils. Neutrophils, basophils, and eosinophils.

Platelets:Platelets: Cellular fragments. 250,000- 400,000/ml of blood. Cellular fragments. 250,000- 400,000/ml of blood.

Important in blood clotting.Important in blood clotting.

Composition of Human Blood

Red Blood Cells Contain Hemoglobin and Transport Gases in Blood

Platelets are Essential for Blood Clotting

2. Heart2. Heart

Anatomical Features:Anatomical Features: Hollow muscular organ, about the size of a human fist.Hollow muscular organ, about the size of a human fist. Weighs less than one pound (10 ounces).Weighs less than one pound (10 ounces). Rests on diaphragm, near middle of thoracic cavity.Rests on diaphragm, near middle of thoracic cavity. Wall is composed of cardiac muscle covered by Wall is composed of cardiac muscle covered by

connective tissue.connective tissue.

PericardiumPericardium: Membrane that surrounds entire : Membrane that surrounds entire heart and contains a fluid which protects heart heart and contains a fluid which protects heart and decreases friction.and decreases friction.

Position of Heart in Thoracic Cavity

2. Heart2. Heart

Heart ChambersHeart Chambers: Heart is divided into four : Heart is divided into four separate chambers. Both the left and the separate chambers. Both the left and the right side of the heart have a(an):right side of the heart have a(an): Atrium (Plural atria)Atrium (Plural atria): Smaller, : Smaller, superiorsuperior

chambers. chambers. ReceiveReceive blood from veins. blood from veins. VentricleVentricle: Larger, : Larger, inferiorinferior chambers. chambers. PumpPump

blood into arteries.blood into arteries.

Two sides of heart have different functions:Two sides of heart have different functions: Right sideRight side: Pumps oxygen poor blood.: Pumps oxygen poor blood. Left sideLeft side: Pumps oxygen rich blood.: Pumps oxygen rich blood.

Structure of the Human Heart

Right side pumps O2 poor blood. Left side pumps O2 rich blood

Pacemaker (Sinoatrial node): Specialized structure that sends electrical impulses that causes both atria and ventricles to contract.

2. Heart2. Heart

Heart ValvesHeart Valves: Heart has several valves made of : Heart has several valves made of connective tissue, that prevent backflow of blood connective tissue, that prevent backflow of blood as it circulates.as it circulates.

Atrioventricular (AV) ValvesAtrioventricular (AV) Valves: Close between : Close between atria and ventriclesatria and ventricles Right AV Valve:Right AV Valve: Connects right atrium to the right ventricle. Connects right atrium to the right ventricle. Left AV Valve:Left AV Valve: Connects left atrium to the left ventricle. Connects left atrium to the left ventricle.

Semilunar ValvesSemilunar Valves: Close as blood leaves the : Close as blood leaves the ventricles and enters the arteries.ventricles and enters the arteries.

Heart murmurHeart murmur: Rushing, gurgling sound created by : Rushing, gurgling sound created by backflow of blood due to damaged or imperfect backflow of blood due to damaged or imperfect heart valves. Fairly common (10% of healthy heart valves. Fairly common (10% of healthy population). Most are asymptomatic.population). Most are asymptomatic.

Internal Structure of the Human Heart

3. Blood Vessels3. Blood Vessels

Include arteries, arterioles, capillaries, venules, Include arteries, arterioles, capillaries, venules,

and veins.and veins.

Double circuit, closed system:Double circuit, closed system:

1. Pulmonary circuit: 1. Pulmonary circuit: Delivers blood to lungs. Delivers blood to lungs.

Oxygenation of blood.Oxygenation of blood.

2. Systemic circuit: 2. Systemic circuit: Delivers oxygenated blood to Delivers oxygenated blood to

tissues and organs of body (brain, liver, heart, tissues and organs of body (brain, liver, heart,

kidneys, etc). Picks up carbon dioxide produced kidneys, etc). Picks up carbon dioxide produced

by tissues.by tissues.

Structure of Different Blood Vessels

Pulmonary and Systemic Circuits

3. Types of Blood Vessels3. Types of Blood Vessels

A. Arteries and Arterioles: A. Arteries and Arterioles: Carry blood Carry blood awayaway fromfrom heartheart to body. to body. Have high pressure.Have high pressure. Have thick muscular walls, which make them Have thick muscular walls, which make them

elastic and contractile.elastic and contractile. Vasoconstriction:Vasoconstriction: Arteries contract: Arteries contract:

Reducing flow of blood into capillaries.Reducing flow of blood into capillaries. Increasing blood pressure.Increasing blood pressure.

Vasodilation:Vasodilation: Arteries relax: Arteries relax: Increasing blood flow into capillaries.Increasing blood flow into capillaries. Decreasing blood pressure.Decreasing blood pressure.

Control of Capillary Blood Flow by Arteriole Constriction

3. Types of Blood Vessels3. Types of Blood Vessels

Capillaries: Capillaries: Only blood vessels whose walls are thin Only blood vessels whose walls are thin enough to permit gas exchange.enough to permit gas exchange.

Blood flows through capillaries relatively slowly, Blood flows through capillaries relatively slowly, allowing sufficient time for diffusion or active allowing sufficient time for diffusion or active transport of substances across walls.transport of substances across walls.

Only about 5 to 10% of capillaries have blood Only about 5 to 10% of capillaries have blood flowing through them. Only a few organs (brain flowing through them. Only a few organs (brain and heart) always carry full load of blood. and heart) always carry full load of blood.

Blood flow to different organs is controlled by Blood flow to different organs is controlled by precapillary sphinctersprecapillary sphincters of smooth muscle. of smooth muscle.

Control of Capillary Blood Flow by Precapillary Sphincters

Movement of Fluid Across Capillary Walls

99% of fluid that leaves capillary at arteriole end, reenters at venous end. Remaining 1% is returned by lymphatic vessels.

3. Types of Blood Vessels3. Types of Blood Vessels

Veins and Venules:Veins and Venules:

Collect blood from all tissues and organs and Collect blood from all tissues and organs and

carrycarry it back it back towardstowards heart. heart.

Have low pressure and thin walls.Have low pressure and thin walls.

Veins have small Veins have small valvesvalves that prevent backflow of that prevent backflow of

blood towards capillaries, especially when blood towards capillaries, especially when

standing. If the valves cease to work properly, standing. If the valves cease to work properly,

may result in:may result in: Varicose veinsVaricose veins: Distended veins in thighs and legs.: Distended veins in thighs and legs.

HemorroidsHemorroids:: Distended veins and inflammation of the rectal and Distended veins and inflammation of the rectal and

anal areas.anal areas.

Veins Contain Valves to Prevent Backflow of Blood

Heart BeatHeart Beat Average 70 beats per minute. Average 70 beats per minute. 100,000 beats every day.100,000 beats every day. Cardiac cycleCardiac cycle about every 0.8 sec. about every 0.8 sec.

DiastoleDiastole: Heart relaxes and blood flows into chambers (0.4 sec).: Heart relaxes and blood flows into chambers (0.4 sec). SystoleSystole: Heart contracts. : Heart contracts.

• First atria (0.1 sec)First atria (0.1 sec)

• Then ventricles (0.3 sec)Then ventricles (0.3 sec)

Pumps about 8000 liters of blood/day.Pumps about 8000 liters of blood/day. Pacemaker (Sinoatrial node): Controls heart rate.Pacemaker (Sinoatrial node): Controls heart rate.

Regulated by nervous and endocrine systems.Regulated by nervous and endocrine systems.

Two heart beat sounds (“Lub-dupp”):Two heart beat sounds (“Lub-dupp”): First sound:First sound: Ventricles contract, AV valves close. Ventricles contract, AV valves close. Second soundSecond sound: Heart relaxes, semilunar valves are : Heart relaxes, semilunar valves are closingclosing..

PulsePulse: Arteries expand and contract with each heartbeat.: Arteries expand and contract with each heartbeat.

Stages of Cardiac Cycle

FirstSound“Lub”

Diastole: Heart Relaxes Systole: Heart contracts

SecondSound“Dupp”

Pacemaker Controls Cardiac Rhythm

Blood PressureBlood Pressure Pressure is highest in arteries; lowest in veins. Pressure is highest in arteries; lowest in veins.

““Blood pressureBlood pressure” usually refers to ” usually refers to arterialarterial pressure. pressure.

Usually measured at Usually measured at brachial arterybrachial artery in arm. in arm.

Two measurements:Two measurements:

Systolic Blood PressureSystolic Blood Pressure: During heart : During heart contractioncontraction. .

Normal systolic pressure is about 120 mm Hg.Normal systolic pressure is about 120 mm Hg.

(Range: 110-140 mm Hg).(Range: 110-140 mm Hg).

Diastolic Blood PressureDiastolic Blood Pressure: During heart : During heart relaxationrelaxation. .

Normal diastolic pressure is about 80 mm Hg.Normal diastolic pressure is about 80 mm Hg.

(Range: 70-90 mm Hg)(Range: 70-90 mm Hg)

Measuring Systolic and Diastolic Blood Pressure

Blood Pressure and Velocity in Blood Vessels

Blood Pathway in BodyBlood Pathway in Body Right Side of HeartRight Side of Heart: :

Right atrium receives oxygen poor blood from body.Right atrium receives oxygen poor blood from body.

Right ventricle pumps oxygen poor blood to lungs. Right ventricle pumps oxygen poor blood to lungs.

Left Side of HeartLeft Side of Heart: :

Left atrium receives oxygenated blood from lungs.Left atrium receives oxygenated blood from lungs.

Left ventricle pumps oxygenated blood to body. Left ventricle pumps oxygenated blood to body.

Blood PathwayBlood Pathway::Veins ---> Vena cava ---> Veins ---> Vena cava ---> Right atriumRight atrium ---> ---> Right ventricleRight ventricle ---> --->

Pulmonary artery ---> Lungs ---> Pulmonary artery ---> Lungs ---> Left atriumLeft atrium ---> ---> Left ventricleLeft ventricle ---> --->

Aorta ---> Arteries ---> Aorta ---> Arteries ---> CapillariesCapillaries ---> Veins ---> Veins

Path of Blood Flow through Cardiovascular System

Cardiovascular DiseaseCardiovascular Disease

Number one cause of death in the U.S. and Number one cause of death in the U.S. and

industrialized nations.industrialized nations.

Includes hypertension, strokes, heart attacks, and Includes hypertension, strokes, heart attacks, and

congestive heart failure.congestive heart failure.

Most often caused by complications of: Most often caused by complications of:

ArteriosclerosisArteriosclerosis: A condition in which arteries : A condition in which arteries

become blocked by calcium and lipid deposits become blocked by calcium and lipid deposits

((plaqueplaque), losing their elasticity.), losing their elasticity.

Heart Attack (Myocardial infarction-MI)Heart Attack (Myocardial infarction-MI) Sudden decrease in blood supply to the heart, due to a clot Sudden decrease in blood supply to the heart, due to a clot

or plaque in arteries. or plaque in arteries.

Death of cardiac muscle resulting in insufficient blood Death of cardiac muscle resulting in insufficient blood

supply to rest of body. supply to rest of body.

Heart may stop beating altogether or suffer permanent Heart may stop beating altogether or suffer permanent

damage.damage.

Over 1.3 million heart attacks every year in U.S.Over 1.3 million heart attacks every year in U.S. Leading cause of death and disabilityLeading cause of death and disability

60% had no previous symptoms. 60% had no previous symptoms.

25% are not recognized when they occur.25% are not recognized when they occur.

25% die before receiving medical assistance.25% die before receiving medical assistance.

In 1995 960,000 deaths in U.S. In 1995 960,000 deaths in U.S.

Heart Attacks are Caused by Blocked Coronary Arteries

Heart Attack (Myocardial infarction)Heart Attack (Myocardial infarction) Symptoms:Symptoms: Chest pain, pressure, or tightness, sweating, Chest pain, pressure, or tightness, sweating,

nausea, shortness of breath, dizziness, and fainting.nausea, shortness of breath, dizziness, and fainting.

Risk factorsRisk factors:: SmokingSmoking High blood pressureHigh blood pressure High cholesterolHigh cholesterol High LDLs (low density lipoproteins)High LDLs (low density lipoproteins) DiabetesDiabetes Male genderMale gender Emotional stressEmotional stress ObesityObesity HeredityHeredity Sedentary lifestyleSedentary lifestyle

HypertensionHypertension: High blood pressure.: High blood pressure. Blood pressure over 140/90.Blood pressure over 140/90.

Over 20% of U.S. population suffers from blood Over 20% of U.S. population suffers from blood

pressures over 160/95. pressures over 160/95.

Another 25% is borderline (above 140/90).Another 25% is borderline (above 140/90).

Heart must work harder to overcome resistance.Heart must work harder to overcome resistance.

Silent killerSilent killer: May have few or no symptoms.: May have few or no symptoms.

May result in strokes, heart attacks, aneurysms, May result in strokes, heart attacks, aneurysms,

ischemia (insufficient blood supply to heart) and ischemia (insufficient blood supply to heart) and

arteriosclerosis. arteriosclerosis.

Risk factorsRisk factors: Heredity, obesity, high salt intake, black : Heredity, obesity, high salt intake, black

race (relative risk 2), smoking, stress, diet high in fat, race (relative risk 2), smoking, stress, diet high in fat,

and lack of exercise.and lack of exercise.

Ischemic Heart DiseaseIschemic Heart Disease:: Insufficient blood supply to the heart.Insufficient blood supply to the heart.

Especially during exercise or physical exertion. Especially during exercise or physical exertion.

May cause May cause angina pectorisangina pectoris: sharp chest pain.: sharp chest pain.

Congestive Heart FailureCongestive Heart Failure:: Heart cannot pump enough blood to meet body’s Heart cannot pump enough blood to meet body’s

needs.needs.

Slow blood flow causes veins to back up causing Slow blood flow causes veins to back up causing edemaedema

in tissue (legs, tissues, or lungs).in tissue (legs, tissues, or lungs).

SymptomsSymptoms: Shortness of breath, edema, and fatigue.: Shortness of breath, edema, and fatigue.

CausesCauses: Hypertension , arteriosclerosis, heart valve : Hypertension , arteriosclerosis, heart valve

damage, heart attack, etc.damage, heart attack, etc.

StrokeStroke:: Third leading cause of death in U.S. after heart disease Third leading cause of death in U.S. after heart disease

and cancer.and cancer.

• 5% of people over 65 have had a stroke.5% of people over 65 have had a stroke.

• 400,000 stroke victims discharged from hospitals every year.400,000 stroke victims discharged from hospitals every year.

Insufficient blood supply to the brain, caused by a Insufficient blood supply to the brain, caused by a

blood clot or rupture of a blood vessel.blood clot or rupture of a blood vessel.

Depending on area affected may cause:Depending on area affected may cause:

• Paralysis (usually one side of body).Paralysis (usually one side of body).

• Loss of sensation or motor control.Loss of sensation or motor control.

• IncontinenceIncontinence

• Loss of speech, hearing, or sight.Loss of speech, hearing, or sight.

• Death Death

Relationship between major organ systems