Heart Structure & Function16-17 March 2015

What questions do you have about the heart?

Cardiovascular SystemWhat is the major function of the cardiovascular system? • To transport materials (oxygen, nutrients, wastes, hormones, immune components, heat, etc.) throughout the body

What is the heart’s role in this system, and what are the other major components?•Heart is the pump – supplies the force to move the blood.• Blood carries the materials• Vessels are roads and exchange surfaces

Heart Location & Size

Heart Layers Pericarditis is inflammation of the pericardium.

Anterior view & Cardiac CirculationCardiac vessels supply the heart muscle itself with blood.

Heart disease (atherosclerosis) occurs when the aorta or cardiac arteries become clogged with fatty plaques.

Heart Anatomy (Frontal Section)

The Heart is a Double Pump

• The right side of the heart receives oxygen-poor blood from the body and pumps it to the lungs

pulmonary circulation

• The left side of the heart receives oxygen-rich blood from the lungs and pumps it to the body

systemic circulation

The heart has four chambersEach side has an atrium for collecting blood and a ventricle for pumping blood to the lungs or body

Blood collects in atria while ventricles contract.

Then, as ventricles relax, atria contract slightly and ventricles refill.

Two sides of heart contract and relax simultaneously.

Flow of bloodUse the diagram to determine the flow of blood through the heart and body.

Vena cava

Vena cava

R. atrium

R. ventricle

Pulmonary artery

Lung vessels

Pulmonary vein

L. atrium

L. ventricle

aorta Body vessels

Comparison of four chambersThe walls of the ventricles are much thicker than that of the atria? Why?

Ventricles are more muscular, since they are the major pumps.

Look at the diagram – how does the left ventricle differ from the right? What is the reason for the difference? Left ventricle is more muscular – needs to pump blood throughout entire body, while right ventricle just needs to send blood to lungs.

Heart valves ensure unidirectional flowAtrioventricular valves (tricuspid and mitral)• hang open when the ventricles are filling• forced closed when the ventricles contract• anchored by chordae tendineae

AV valves prevent backflow from __________________ to __________________

Heart valves ensure unidirectional flowAtrioventricular valves (tricuspid and mitral)• hang open when the ventricles are filling• forced closed when the ventricles contract• anchored by chordae tendineae•

Semilunar valves (pulmonary and aortic)• forced open when

ventricles contract• closed when

ventricles relax

AV valves prevent backflow from ventricles to atria

SL valves prevent backflow from ________ to__________

Heart valves ensure unidirectional flowAtrioventricular valves (tricuspid and mitral)• hang open when the ventricles are filling• forced closed when the ventricles contract• anchored by chordae tendineae•

Semilunar valves (pulmonary and aortic)• forced open when

ventricles contract• closed when

ventricles relax

AV valves prevent backflow from ventricles to atria

SL valves prevent backflow from arteries to ventricles

Heart valves ensure unidirectional flowIn what stage of the cardiac cycle is the heart shown below? How do you know?

Ventricles are contracting(in systole) because SL valves open (and AV valves close) when ventricles contract to force blood only towards arteries.

Atria are relaxed (in diastole)Where else have you heard these words?

Heart SoundsNormal hearts make the sound:

LUB-dup LUB-dup LUB-dup

The “LUB” is caused by the closing of the AV valves.The “dup” is caused by the closing of the semilunar valves.Heart murmurs are abnormal

heart sounds. • In children, these are often

benign.• In adults, they usually indicate

a problem – often, the failure of the valves to work properly. Why is it a problem if the valves don’t function

properly?

Mitral valve murmurAortic stenosis murmur

Quick Review & Fill in & Exit Ticket

Closure & HW

What questions did we answer today? What haven’t we answered?What new questions do you have?

HOMEWORKWed / Thursday – Present answers to questionsFriday / Monday – Review Exercise 20Quiz next Wednesday or Friday