Functional Anatomy of the Heart

Question 1

How is blood pressure in the pulmonary and systematic circulation generated?

Answer 1

1. deoxygenated blood enters the relaxed right atrium via the primary cranial and caudal vena cava
2. the right ventricle fills mostly through passive as blood flows into it through the open right AV valve
3. right atrium contracts at the end of the right ventricular filling
4. contraction increases ventricular pressure, causing closure of the right AV valve and the opening od the pulmonary valve
5. blood passes through the pulmonary valve into the pulmonary trunk to the lungs
6. right ventricle relaxes, decreasing right ventricle pressure
7. pulmonary valve closes to prevent back flow, and the right AV valve opens allowing the right ventricle to fill again
8. oxygenated blood returns from the lungs via the pulmonary veins to fill the left atrium
9. pressure and volume increase in the left atrium
10. blood flows into the left ventricle through the open left AV valve
11. left atrium contracts at end of left ventricular filling
12. left Av valve closes as aortic valve opens
13. blood flows into aorta and rest of body
14. left ventricle relaxes and pressure drops, closing the aortic valve to prevent back flow

Question 2

What happens during diastole?

Answer 2

All four chambers are simultaneously relaxed when normally the two atria contract simultaneously followed by the two ventricle. During diastole, two heart sounds are heard. First occurs during ventricular systole and is caused by the AV valves snapping shut. The second is heard during diastole and is similarly caused by the closure of the pulmonary and aortic valves