Functions of the vascular system

Question 1

What is the pulmonary system?

Answer 1

Includes the pulmonary artery and pulmonary vein. Blood entering the heart from body deoxygenated going to lungs for oxidation via the pulmonary artery then returning oxygenated back to the heart via the pulmonary vein.

Question 2

What is venous return?

Answer 2

Venous return is the transport of blood from the capillaries through venules, veins and then either superior or inferior vena cava back to the right atrium of the heart.

Question 3

What factors affect how venous return occurs?

Answer 3

skeletal muscle pump, pocket valves, respiratory pump, gravity, smooth muscle, cardiac suction

Question 4

What is Starlings law?

Answer 4

It states that stroke volume is dependent on venous return. Hence, if VR increases so will SV; if VR decreases so will stroke volume. SV directly affects cardiac output Q so if SV increases then so does Q. At rest VR is sufficient to maintain SV and Q sufficient to supply demand for oxygen. During exercise the pressure of blood in the veins is too low to maintain VR and SV and Q therefore decreases.