16-17 March 2015

What 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

Pericarditis is inflammation of the pericardium.

Cardiac vessels supply the heart muscle itself with blood.
Heart disease (atherosclerosis) occurs when the aorta or cardiac arteries become clogged with fatty plaques.

• 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

Each 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.

Use the diagram to determine the flow of blood through the heart and body.
Vena cava  R. atrium 
R. ventricle
Lung vessels
L. atrium



Pulmonary
 artery
Pulmonary  vein
L. ventricle  aorta  Body vessels 
Vena cava

The 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.

Atrioventricular 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
__________________

Atrioventricular 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
SL valves prevent backflow from
________ to__________
AV valves prevent backflow from ventricles to atria

Atrioventricular 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
SL valves prevent backflow from arteries to ventricles
AV valves prevent backflow from ventricles to atria

In 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?

Normal 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.
Mitral valve murmur
Aortic stenosis murmur
Why is it a problem if the valves don’t function properly?

What questions did we answer today?
What haven’t we answered?
What new questions do you have?
HOMEWORK
Wed / Thursday – Present answers to questions
Friday / Monday – Review Exercise 20
Quiz next Wednesday or Friday