Control Of Cardiac Output

Question 1

If cardiac output is fixed and total peripheral resistance falls, what will happen to arterial and venous pressure?

Answer 1

Arterial will fall and venous will rise.

Question 2

If cardiac output is fixed and total peripheral resistance rises, what will happen to arterial and venous pressure?

Answer 2

Arterial will rise and venous will fall.

Question 3

If total peripheral resistance is fixed and cardiac output falls, what will happen to arterial and venous pressure?

Answer 3

Arterial pressure falls and venous pressure rises

Question 4

If total peripheral resistance is fixed and cardiac output rises, what will happen to arterial and venous pressure?

Answer 4

Arterial pressure rises and venous pressure falls.

Question 5

What changes total peripheral resistance?

Extra point - how does it signal this?

Answer 5

A change in metabolism.

Extra point - in the form of arterial and venous pressure.

Question 6

What is demand led pumping?

Answer 6

The heart responds to a decrease I’m arterial pressure and an increase in venous pressure by pumping more blood.

Question 7

The higher the venous pressure, the more the heart fills. Why is this?
Extra point - what is this called?

Answer 7

In diastole the ventricle is connected to the veins only. This fills until the walls stretch enough to make the intra ventricular pressure = venous pressure.
Extra point - known as ventricular compliance curve.

Question 8

What does Starings law state about the strength of heart contraction?

Answer 8

The more the muscle is stretched before contraction, the harder it will contract.

Question 9

If the heart contracts harder, what happens to the stroke volume?

Answer 9

It will increase.

Question 10

What does a rise in venous pressure do to the stroke volume?

Answer 10

Increases it.

Question 11

What does the Starling curve relate to one another?

Answer 11

Stroke volume to venous pressure. (Known as contractility of ventricle)

Question 12

What does the end systolic volume rely on?

Answer 12

How much the ventricle empties which depends on how hard it contracts and how difficult it is to eject the blood.

Question 13

What does the force of contraction depend on?

Which branch of the ANS increases this?

Answer 13

The end diastolic volume and contractility.

Extra point - this is increased by sympathetic activation.

Question 14

What is aortic impedance?

Answer 14

The difficulty of ejecting blood.

Question 15

What does aortic impedance depend on?

Answer 15

Mainly on the total peripheral resistance.

Question 16

If it easier to eject blood will more come out in systole or diastole?

Answer 16

Systole. If arterial pressure falls, the end systolic volume will fall and stroke volume will rise

Question 17

What is the effect of an increased venous pressure on stroke volume?

Answer 17

The stroke volume will rise.

Question 18

What is the effect of decreased arterial pressure on stroke volume?

Answer 18

Stroke volume will increase.

Question 19

How is the autonomic outflow of the heart controlled?

Answer 19

By signals from Baroreceptors.

Question 20

What senses arterial pressure?

Answer 20

The carotid sinus.

Question 21

If there is a fall in arterial pressure, how is the heart rate increased?

Answer 21

By reducing parasympathetic activity and increasing sympathetic activity.

Question 22

If there is a fall in arterial pressure, how is the contractility increased?

Answer 22

By increasing sympathetic activity.

Question 23

If venous pressure rises, what is the effect on cardiac output?

Answer 23

It will rise.

Question 24

If arterial pressure falls, what is the effect on cardiac output?

Answer 24

Cardiac output rises.