Circulation and the heart Circulation and the heart

Topical outline Topical outline

I-Location of the heartI-Location of the heart II-Structure of the heartII-Structure of the heart Division of the heartDivision of the heart III-Function of the heartIII-Function of the heart

Circulation Circulation The continuous one way circuit of The continuous one way circuit of

blood through the body in the blood blood through the body in the blood vessels is known as the circulation . vessels is known as the circulation .

Location of the heartLocation of the heart

The heart is slightly bigger than a The heart is slightly bigger than a person's fist. This organ is located person's fist. This organ is located between the lungs in the center and between the lungs in the center and a bite to the left of the midline of the a bite to the left of the midline of the body.body.

Structure of the heartStructure of the heart

The heart is a hollow organ , with The heart is a hollow organ , with walls formed of three different layers walls formed of three different layers

EndocardiumEndocardiumLocationLocation

Innermost Innermost layer of layer of the heart the heart wallwall

Description Description Thin Thin smooth smooth layer of layer of epithelial epithelial cellcell

Function Lines Function Lines the interior of the interior of the chambers the chambers and covers the and covers the heart valvesheart valves

MyocardiumMyocardiumMiddle Middle layer of layer of the heart the heart wallwall

Thick layer Thick layer of cardiac of cardiac musclemuscle

Contracts to Contracts to pump blood pump blood into the into the arteries arteries

Epicardium Epicardium OutermostOutermost

layer of layer of the heart the heart

Thin serous Thin serous membrane membrane

Covers the Covers the heart and heart and forms the forms the visceral layer visceral layer of the serous of the serous pericardium pericardium

Division of the heartDivision of the heart

Health care professional often refer Health care professional often refer to the right heart and the left heart, to the right heart and the left heart, because the human heart is really a because the human heart is really a double pump. The right side pumps double pump. The right side pumps blood low in oxygen to the lungs blood low in oxygen to the lungs through the pulmonary circuit. through the pulmonary circuit.

The left side pumps oxygenated The left side pumps oxygenated blood to the remainder of the body blood to the remainder of the body through the systematic circuit. Each through the systematic circuit. Each side of the heart is divided into two side of the heart is divided into two chamberschambers

Chambers of the heartChambers of the heart

Chamber Chamber locationlocationFunction Function

Right atriumRight atriumUpper right Upper right chamberchamber

Receives blood Receives blood from the vena from the vena cava and the cava and the coronary sinus; coronary sinus; pumps blood into pumps blood into the right ventricle the right ventricle

Right ventricleRight ventricleLower right Lower right chamber chamber

Receives blood Receives blood from the right from the right atrium and pumps atrium and pumps blood into the blood into the pulmonary artery, pulmonary artery, which carries which carries blood to the lungs blood to the lungs to be oxygenated. to be oxygenated.

chamberchamberlocationlocationFunction Function

Left Left atriumatrium

Upper left Upper left chamberchamber

Receive oxygenated Receive oxygenated coming back to the coming back to the heart from the lungs heart from the lungs in the pulmonary in the pulmonary veins; pump blood veins; pump blood into the left ventricleinto the left ventricle

Left Left ventricleventricle

Lower left Lower left chamberchamber

Receive blood from Receive blood from the left atrium and the left atrium and pumps blood into the pumps blood into the aorta to be carried to aorta to be carried to tissues tissues

Blood supply to the Blood supply to the myocardiummyocardium

the main arteries that supply blood the main arteries that supply blood to the muscle of the heart are the to the muscle of the heart are the right and left coronary arteriesright and left coronary arteries

Valves of the heartValves of the heartValve Valve Location Location Description Description Function Function

Right AV Right AV valve valve

Between Between the right the right atrium atrium and right and right ventricle ventricle

Valve with Valve with three cusps: three cusps: tricuspid tricuspid valve valve

Prevents blood Prevents blood from flowing from flowing back up into the back up into the right atrium right atrium when the right when the right ventricle ventricle contracts contracts (systole)(systole)

Left AV Left AV valve valve

Between Between the left the left atrium atrium and left and left ventricle ventricle

Valve with Valve with two cusps: two cusps: bicuspid or bicuspid or mitral valve mitral valve

Prevents blood Prevents blood from flowing from flowing back up into the back up into the left atrium when left atrium when the left ventricle the left ventricle contracts contracts (systole)(systole)

Valve Valve Location Location Description Description Function Function

PulmonarPulmonary y semilunar semilunar valve valve

At the At the entrance entrance to the to the pulmonarpulmonary artery y artery

Valve with Valve with three half-three half-moon moon shaped shaped cusps cusps

Prevents blood Prevents blood from flowing from flowing back into the back into the ventricle when ventricle when the right the right ventricle relaxes ventricle relaxes (diastole) (diastole)

Aortic Aortic semilunar semilunar valvevalve

At the At the entrance entrance to the to the aortaaorta

Valve with Valve with three half- three half- moon moon shaped shaped cusps cusps

Prevents blood Prevents blood from flowing from flowing back into the back into the left ventricle left ventricle when the left when the left ventricle relaxes ventricle relaxes (diastole)(diastole)

Function of the heartFunction of the heart

Cardiac cycleCardiac cycle Blood is squeezed through chamber Blood is squeezed through chamber

by a heart muscle contraction that begins by a heart muscle contraction that begins in the thin –walled upper chambers, the in the thin –walled upper chambers, the atria and is followed by a contraction of atria and is followed by a contraction of the thick muscle of the lower chambers, the thick muscle of the lower chambers, the ventricles. This active phase is called the ventricles. This active phase is called systole, and in each case, it is followed by systole, and in each case, it is followed by a resting period known as diastole.a resting period known as diastole.

One complete sequence of heart One complete sequence of heart contraction and relaxation is called contraction and relaxation is called cardiac cycle. Each cardiac cycle cardiac cycle. Each cardiac cycle represents a single heart-beat. At represents a single heart-beat. At rest, one cycle takes an average of rest, one cycle takes an average of 0,8 seconds0,8 seconds

Cardiac output-volume pumped by Cardiac output-volume pumped by each ventricle per minuteeach ventricle per minute

1-Stroke volume- amount pumped 1-Stroke volume- amount pumped with each beatwith each beat

2-Heart rate- number of beats per 2-Heart rate- number of beats per minuteminute

B-Heart's conduction systemB-Heart's conduction system 1-Sinoatrial node (pacemaker)- at top 1-Sinoatrial node (pacemaker)- at top

right atriumright atrium 2-Artioventriclar node- between atria and 2-Artioventriclar node- between atria and

ventriclesventricles 3-Atrioventricular bundle (bundle of His) – 3-Atrioventricular bundle (bundle of His) –

at top of interventricular septumat top of interventricular septum

a-Bundle branches- right and left, on a-Bundle branches- right and left, on either side of septumeither side of septum

b-Purkinje fibers- b-Purkinje fibers- branch through myocardium of branch through myocardium of ventriclesventricles

C- Control of the heart rateC- Control of the heart rate 1- Autonomic of nervous 1- Autonomic of nervous

system a-system a-Sympathetic system- speeds heart Sympathetic system- speeds heart rate b-rate b-Parasympathetic system-slows heart Parasympathetic system-slows heart rate through vagus nerverate through vagus nerve

2-Variations in heart rates2-Variations in heart rates

a- bradycardia-slower rate than normal: less a- bradycardia-slower rate than normal: less than 60 beats| minute than 60 beats| minute

d- tachycardia-faster rate d- tachycardia-faster rate than normal: more than 100 beats| minute than normal: more than 100 beats| minute c-sinus arrhythmia- c-sinus arrhythmia- related to breathing changes related to breathing changes

d-premature beat- extra d-premature beat- extra systolesystole

D- heart soundsD- heart sounds 1- normal1- normal a-"lubb"-occurs at closing of a-"lubb"-occurs at closing of

artrioventricular valvesartrioventricular valves b-"dupp“ -occurs at closing of semilunar b-"dupp“ -occurs at closing of semilunar

valvesvalves 2- abnormal-murmur2- abnormal-murmur An abnormal sound is called a murmur An abnormal sound is called a murmur

and is usually due to faulty action of a valve fails and is usually due to faulty action of a valve fails to close tightly and blood leaks back, a murmur is to close tightly and blood leaks back, a murmur is heardheard

IV- in The elderlyIV- in The elderly

1-common variations include:1-common variations include: a- decrease in heart size, a- decrease in heart size,

strength of muscle contraction, strength of muscle contraction, flexibility of valves and cardiac out flexibility of valves and cardiac out putput

b-abnormal rhythms, b-abnormal rhythms, temporary failure of conduction temporary failure of conduction systemsystem

V- Maintaining heart healthV- Maintaining heart health

Prevention of heart ailments is based on Prevention of heart ailments is based on identification of cardiovascular risk factors identification of cardiovascular risk factors and modification of those factors that can and modification of those factors that can be changed.be changed.

Risk factors that cannot be modified Risk factors that cannot be modified include the following:include the following:

-Age. The risk of heart disease increases -Age. The risk of heart disease increases with age.with age.

-gender .men have greater risk than -gender .men have greater risk than womenwomen

-hereditary -hereditary

Risk factors that can be Risk factors that can be changed include the followingchanged include the following

smoking, which leads to spasm and smoking, which leads to spasm and hardening of the arterieshardening of the arteries

physical inactivity. lack of exercise physical inactivity. lack of exercise weakens the heart muscle and weakens the heart muscle and decreases the efficiency of the heartdecreases the efficiency of the heart

over weight increases the riskover weight increases the risk high blood pressure (hypertension) high blood pressure (hypertension)

damages heart muscledamages heart muscle

diabetes and gout. both diseases diabetes and gout. both diseases cause damage to small blood cause damage to small blood vesselsvessels

efforts to maintain a efforts to maintain a healthy heart should include having healthy heart should include having regular physical examinations and regular physical examinations and minimizing the risk factors.minimizing the risk factors.

Heart studies using a Heart studies using a stethoscope, ECG or EKG. stethoscope, ECG or EKG.

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