2.1 The Heart as a Pump

Question 0

What is a ‘capacitance vessel’?

Answer 0

A vessel that enables the system to vary the amount of blood in the system.

Question 1

What is a ‘resistance vessel’?

Answer 1

A vessel that limits blood flow to easy to perfuse areas

Question 2

Name the 4 compartments of the heart

Answer 2

Left atrium
Left ventricle
Right atrium
Right ventricle

Question 3

How is the flow of blood controlled within the heart?

Answer 3

Valves

Question 4

What is the name of the atrioventricular valve on the left side of the heart?

Answer 4

Mitral valve

Question 5

What is the name of the atrioventricular valve on the right side of the heart?

Answer 5

Tricuspid valve

Question 6

What is different about a cardiac action potential?

Answer 6

Longer- 280ms

Question 7

What is a ‘pacemaker’?

Answer 7

A pacemaker generates an action potential at regular intervals. The action potential spreads to all of the heart cells to produce a co-ordinated contraction.

Question 8

Describe the process of the ‘spread of excitation’ over the heart

Answer 8

The SAN releases an action potential that spreads over the atria causing atrial systole.
It reaches the AVN where it is held for 120ms.
The action potential then spreads down the septum and up the myocardium from the out to in.
This causes ventricular systole.

Question 9

How often (at rest) is an action potential generated from the SAN?

Answer 9

1 every second

Question 10

What does SAN stand for?

Answer 10

Sinoatrial node

Question 11

How long does ventricular systole last for?

Answer 11

280ms

Question 12

How long does diastole last for?

Answer 12

700ms

Question 13

When the heart rate increases does the:
A: length of diastole shorten?
B: length of ventricular systole shorten?

Answer 13

A: the length of diastole shortens

Question 14

What is the function of the valves?

Answer 14

They allow for uni-directional flow

Question 15

When does the mitral valve open?

Answer 15

When pressure in the left atrium is greater than the pressure in the left ventricle.

Question 16

Why does a small amount of blood regurgitate back into the left atrium when the mitral valve closes?

Answer 16

Blood is regurgitated to lift the valve leaflets. This forces the valve to close.

Question 17

When do the outflow valves open?

Answer 17

The outflow valves open when pressure in the ventricle is greater than the pressure in the arteries.

Question 18

What is the first heart sound (lup)?

Answer 18

The closure of the a/v valves at the beginning of ventricular systole

Question 19

What is the second heart sound (dup)?

Answer 19

Closure of the outflow valves at the end of ventricular systole

Question 20

What are heart murmers?

Answer 20

Additional sounds made by the heart due to turbulent blood flow

Question 21

How is Cardiac Output worked out? And what is the normal value?

Answer 21

Stroke volume x heart rate

80ml x 60bpm = 5 L per min