a. The heart: 4 chambers and 4 sets of valves
b. The systemic circulatory system
c. The pulmonary circulatory system
b. Of the small arteriesThese are the resistance vessels:
Thus the net movement of water across the capillary membrane can be expressed via the equation: Kf[(HPc-HPif)-(COPc-COPif)].
a. Pericardium: Limits cardiac distention with cardiac filling. This effect is greatest on the thin walled chambers such as the atria and the right ventricle.
b. Right Atrium: It serves as a storage reservoir for blood returning to the heart via the cranial and caudal vena cavas.
c. Right Ventricle: It must receive all the blood presented to it via the right atrium and expel this blood to the lungs for gas exchange. Since the pulmonary arterial tree is a rather low-pressure system (as compared to the systemic arteries), the right ventricle develops into a rather thin walled chamber (as compared to the left ventricle).
d. Left Atrium: It serves as a storage reservoir for blood returning from the pulmonary veins.
e. Left Ventricle: It must receive all the blood presented to it via the left atrium and expel this blood through the systemic arterial tree to the organs of the body. Since the systemic arterial tree is a rather high-pressure system (as compared to the pulmonary arteries), the left ventricle develops into a rather thick walled chamber (as compared to the right ventricle).
f. The A-V valves: They function to promote the flow of blood (unidirectional flow only) from the atria to the ventricles during diastole. Flow occurs across these valves when the pressure in the ventricles falls below that of the atria. Flow across the A-V valves is characterized by three phases: rapid filling phase at the onset of diastole (responsible for most of the filling of the ventricle), diastasis (minimal flow occurs at this time), and atrial contraction at the end of diastole.
g. Semilunar valves: They function to promote the flow of blood from the ventricles into the arterial trees during systole. Flow occurs across these valves when the pressure in the ventricles exceeds that present in the arterial tree. Flow across these valves is uni-modal (unlike the bimodal nature of flow across the AV valves).