Overview of Circulation

Question 1

With intermittent pumping of the heart, how is flow uniform?

Answer 1

Distention of aorta and its branches during systole and elastic recoil of those walls and propulsion of blood during diastole (acts like a pump)

Question 2

Why is there a large drop in pressure when blood gets to the arterioles?

Answer 2

High resistance, low flow (cross sectional area inversely related to resistance)

Question 3

How does blood get back to the heart from the veins with such low pressures?

Answer 3

Valves prevent back flow and the skeletal muscles are a sneaky pump

Question 4

What is the relationship between velocity and cross sectional area?

Answer 4

Velocity and cross sectional area are inversely proportional when flow is constant, as cross sectional area of the vasculature increases the velocity of the blood flow decrease dramatically

Question 5

How does blood shift from the venous side to the arterial side?

Answer 5

SNS activates to cause constriction of the veins causing it to shift to the arterial side, increasing MAP

Question 6

Where are some specific blood reservoirs in the body?

Answer 6

Spleen 100mL
Liver sinuses-several hundred
Large abdominal veins- 300mL
Venous plexus underlying skin- several hundred