Cardiac Output

Question 1

What is the basal cardiac output for a 70kg male?

Answer 1

5600 ml/min

Question 2

What is the litre capability of a sedentary 70kg male?

Answer 2

20L / min

Question 3

What is the definition of cardiac output ?

Answer 3

The volume of blood pumped by the left ventricle in one minute.

Question 4

How do you calculate cardiac output?

Answer 4

Heart rate x stroke volume

Question 5

How is the ejection fraction calculated ?

Answer 5

Stroke volume / end diastolic volume

Question 6

What does the ejection fraction tell us?

Answer 6

How hard the heart is working

Question 7

Do athletes have an increased heart rate or stroke volume?

Answer 7

Stroke volume

Question 8

Why does the EDV in a patient with heart failure increase?

Answer 8

The heart is dilated

Question 9

How does the sympathetic NS effect HR?

Answer 9

It speeds up the heart (+ve chronotropic effect)

Question 10

How does the sympathetic NS speed up the heart?

Answer 10

It activated B1 sympathetic receptors which open up calcium channels which allows more calcium into the cells during phase 4.. Ut also speeds up AV conduction.

Question 11

How does the parasympathetic nervous system effect hr?

Answer 11

It slows down the heart (-ve chronotropic effect)

Question 12

How does the parasympathetic NS slow down the heart?

Answer 12

Activation of M2 receptors opens K+channels which slows the opening of Ca++ channels. Slows AV conduction.

Question 13

What is heterometric regulation?

Answer 13

Changes in cardiac output dependent on initial length of cardiac muscle fibre

Question 14

What is homeometric regulation ?

Answer 14

Changes in cardiac output independent on initial length of cardiac muscle fibre

Question 15

What does the Frank-Starking relationship tell us?

Answer 15

Stroke volume and cardiac output is dependent on the degree of stretch on ventricular walls. The more blood put into the heart, the more the heart will stretch, the higher the stroke volume.
More in = more out

Question 16

What are other terms given to preload and afterload?

Answer 16

Preload - end diastolic volume

Afterload - systemic arterial pressure against which the heart is pumping

Question 17

When does decomposition occur?

Answer 17

This occurs when the heart is stretched too much and therefore decreases stroke volume

Question 18

Will will catecholamines (noradrenaline and adrenaline) do to sympathetic NS effects?

Answer 18

They will amplify the effects

Question 19

What type of regulation is the Frank-Stirling law?

Answer 19

Heterometric

Question 20

Define cardiac failure.

Answer 20

Insufficient peripheral perfusion despite normal blood volume, a sufficient filling pressure and intact intrinsic and extrinsic compensatory mechanisms

Question 21

What is the most common cause of cardiac failure?

Answer 21

Coronary artery disease

Question 22

What is an oedema ?

Answer 22

Build up of fluid in a tissue