CV - Quiz 4, part 1, Cardiac Function Curves

Question 1

1. What is mean circulatory filling pressure? (Klabunde, pg. 114)

Answer 1

Pressure at zero systemic flow, which is ~ 7mm Hg

Question 2

2. What is a cardiac function curve? (Klabunde, pg. 116)

Answer 2

(Frank-Starling Relationship) Increase in right atrial pressure increases cardiac output.

Question 3

3. How does contractility affect the cardiac function curve? (Klabunde, pg. 81)

Answer 3

An increase in contractility will cause an increase in stroke volume causing the curve to move up and to the left. A decrease in contractility will have the opposite effect.

Question 4

4. How does afterload affect the cardiac function curve? (Klabunde, pg. 79)

Answer 4

A decrease in afterload causes a greater stroke volume, which shifts the cardiac function curve up and to the left. An opposite affect would occur if the afterload would increase.

Question 5

5. What is a venous return curve? (Guyton p 235)

Answer 5

Curve that shows the relationship between atrial pressure, mean systemic filling pressure, and resistance to blood flow.

Question 6

6. How do blood volume changes affect the venous return curve? (Dr Larson article p 4)

Answer 6

An increase in blood volume increases mean systemic filling pressure and shifts the hinge point to the right. A decrease in blood volume decreases mean systemic filling pressure and shifts the hinge point to the left

Question 7

7. How do venous compliance changes affect the venous return curve? (Klabunde, pg. 115)

Answer 7

An increase in venous compliance leads to a decrease in volume moves the Pms to left. A decrease in venous compliance leads to a increase in volume and moves the Pms to the right.

Question 8

8. How do systemic vascular resistance changes affect the venous return curve? (Klabunde, pg. 115)

Answer 8

An increase in the SVR will cause a decrease in the slope while keeping the same mean circulatory filling pressure (slope moves down). A decrease in the SVR will cause an increase in the slope while keeping the same mean circulatory filling pressure (slope moves up).

Question 9

9. What things will change the mean circulatory filling pressure? (Klabunde, pg. 115)

Answer 9

Volume and Venous Compliance

Question 10

When does cardiac output equal venous return?

Answer 10

It should be equal most of the time (Frank-Starling Mechanism) at “Steady-State”

Question 11

What is the intersection of the cardiac function and venous return curves?

Answer 11

• equilibrium point, right atrial pressure intersect (normal cadiac output 5L/min and right atrial pressure of 0mmHg

Question 12

12. Why is the venous return curve horizontal as right atrial pressure becomes negative? (Guyton p 235)

Answer 12

negative pressure in the chest will cause the veins to collapse until it reaches a pressure of 0mm Hg.