Chapter14 - The Heart

Copyright © 2012 F.A. Davis Company

Understanding Anatomy & PhysiologyUnderstanding Anatomy & PhysiologyA Visual, Interactive ApproachA Visual, Interactive Approach

Chapter 14

The HeartThe Heart



Base

Apex



Heart structuresHeart structures

Fibrouspericardium

Serouspericardium



Parietal layer

Pericardial cavity

Endocardium

Myocardium

Epicardium(Visceral layer)



Heart chambersHeart chambers



The sac surrounding the heart is the:

A.epicardium.B.endocardium.C.myocardium.D.pericardium.



Correct answer: D

Rationale:The endocardium, myocardium, and epicardium are the three layers of the heart wall.



Heart valvesHeart valves



Heart skeletonHeart skeleton



Heart soundsHeart sounds



Which heart valve controls the flow of blood between the left atria and the left ventricle?

A.Pulmonary valveB.Aortic valveC.Tricuspid valveD.Mitral valve



Correct answer: D

Rationale:The pulmonary valve prevents backflow from the pulmonary artery to the right ventricle. The aortic valve prevents backflow from the aorta to the left ventricle. The tricuspid valve prevents backflow from the right ventricle to the right atrium.



Blood flow through the heartBlood flow through the heart1. 2.



3. 4.



5.

View animation of blood flow through the heart

6.



Coronary circulationCoronary circulationCoronary arteriesCoronary arteries Coronary veinsCoronary veins

Left coronaryartery

Right coronaryartery

Coronary sinus



Which great vessel supplies blood to the right atrium?

A.Superior and inferior vena cavaeB.AortaC.Pulmonary arteryD.Pulmonary veins



Correct answer: A

Rationale:The aorta receives blood from the left ventricle. The pulmonary artery receives blood from the right ventricle. The pulmonary veins transport blood from the lungs to the left atrium.



Cardiac conductionCardiac conduction

View animation of cardiac conduction

11 22

33

44

55

66



ElectrocardiogramElectrocardiogram



Cardiac cycleCardiac cycle The series of events from the

beginning of one heartbeat to the beginning of the next

Consists of systolesystole (contraction) and diastolediastole (relaxation)



Cardiac cycleCardiac cycle

Returning blood fills atria; pressure ↑ Atrioventricular valves open; blood

flows into ventricles P wave appears on

electrocardiogram (marking end of atrial depolarization)

Phase 1: Passive ventricular fillingPhase 1: Passive ventricular filling




Atrioventricular valves are open; semilunar valves are closed

Atria contract, ejecting remaining blood

Ventricles are relaxed and fill

Phase 2: Atrial systolePhase 2: Atrial systole




Ventricles begin to contract; semilunar valves are still closed

Pressure ↑ rapidly R wave appears on ECG First heart sound (S1) can be heard

Phase 3: Isovolumetric contractionPhase 3: Isovolumetric contraction




Semilunar valves open Blood spurts out of each ventricle Some blood remains (residual

volume) T wave occurs at peak ventricular

pressure

Phase 4: Ventricular ejectionPhase 4: Ventricular ejection




Occurs before atrioventricular valves open and after semilunar valves have closed

Pressure in ventricles ↓ T wave ends on electrocardiogram Second heart sound (S2) can be heardView animation of cardiac cycle

Phase 5: Isovolumetric ventricular relaxationPhase 5: Isovolumetric ventricular relaxation



What is the heart’s primary pacemaker?

A.Atrioventricular (AV) nodeB.Purkinje fibersC.Sympathetic nervous systemD.Sinoatrial (SA) node



Correct answer: D

Rationale:If the SA node fails, the AV node and the Purkinje fibers can initiate impulses, but they are not the primary pacemakers. The sympathetic nervous system can alter the heart’s rate, but it does not act as a pacemaker.



Cardiac outputCardiac output

Cardiac output = Heart rate × Stroke volume



Input to cardiac centerInput to cardiac center ProprioceptorsProprioceptors: Muscles and joints BaroreceptorsBaroreceptors (pressoreceptorspressoreceptors):

Aorta and internal carotids ChemoreceptorsChemoreceptors: Aortic arch,

carotids, and medulla



Factors that affect stroke Factors that affect stroke volumevolume

Preload Contractility Afterload



PreloadPreload The amount of tension in ventricular

muscle before it contracts More blood = more stretch



ContractilityContractility The force with which ventricular

ejection occurs The greater the stretch, the more

forceful the contraction



AfterloadAfterload The forces the heart must work

against An increase in afterload → decreased

stroke volume

View animation of preload, contractility, and afterload



Cardiac output equals:

A.heart rate times stroke volume.B.stroke volume times ejection fraction.C.age times heart rate.D.the percentage of blood ejected by the ventricles with each contraction.



Correct answer: A

Rationale:Cardiac output is the amount of blood pumped by the heart in 1 minute. This number is derived by multiplying the amount of blood ejected with each beat (stroke volume) by the number of times the heart beats each minute.



Left ventricular failureLeft ventricular failure Blood backs up to the lungs Shortness of breath, pulmonary

edema, and coughing result



Right ventricular failureRight ventricular failure Blood backs up into the vena cava

and peripheral vascular system Generalized swelling, enlarged liver

and spleen, pooling of blood in abdomen, and jugular vein distension results

Chapter14 - The Heart

Health & Medicine

Transcript of Chapter14 - The Heart