Frank Starling Curves

Question 1

The Frank-Starling effect states that as cardiac muscle is increasingly stretched, the _______ increases up to a limit.

Answer 1

cardiac output

Question 2

What is the Y axis and X axis of the cardiac functioning curve?

Answer 2

X: CO or Venous Return Y: RA pressure

Question 3

Where the venous return curve intersects with the x-axis, it indicates the venous return is _____.

Answer 3

zero

Question 4

The dashed lines in the image below depict decreased cardiac output and an unchanged venous return (unchanged blood volume and TPR). An isolated decrease in cardiac output indicates

what ?

What can cause this change?

Answer 4

decreased contractility that is not the result of decreased preload (because the venous return line is unchanged).

This indicates inhibited contraction either from the action of a

• negative inotropic drug
• an injury to the myocardium (myocardial infarction)

Question 5

What can cause a shift in the x-intercept to the right like this?

Answer 5

Increases in blood volume (such as with excessive hydration, dashed line)

Question 6

What causes the X intercept to shift left like this?

Answer 6

decreased blood volume (acute hemorrhage, dashed line)

shifts it to the left

Question 7

What affects the slope of both the venous return and cardiac output curves?

Answer 7

Total peripheral resistance (TPR)

Question 8

_____ in the TPR decrease the slope of both curves, as higher vascular resistance restricts venous return and increases afterload.

Answer 8

Increases

Question 9

What can cause an increase in the slope and height of the cardiac output graph.

Answer 9

Chronic anemia causes an increase in cardiac output in an effort to meet the metabolic demands of the tissues.

Venous return also increases somewhat due to decreased blood viscosity

Question 10

What causes these a drop in Venous Return (shifted down and leftward) and an increase in cardiac contractility?

Answer 10

Anaphylaxis causes widespread venous and arteriolar dilation along with increased capillary permeability and third-spacing of fluids.

This results in a serious drop in venous return

Cardiac contractility also increase as the body attempts to maintain blood pressure.

Question 11

How does increased Contractility affect the curve?

Answer 11

causes an increase in the slope and height of the cardiac output curve

Question 12

What can change the Venous Return’s intercept on the Y (vertical) and X (horizontal) axis?

Answer 12

Increased Venous Return and blood volume shifts the Y intercept UP and X intercept to the right

Increases or massive decreases in TPR Shifts the Y intercept down and X intercept Left