The control and regulation of the heart

Question 1

What does the autonomic nervous system do?

Answer 1

Determines the rate at which the SA node sends impulses.

Question 2

What is the sympathetic nervous system responsible for?

Answer 2

Increasing the hart rate during exercise.

Question 3

What is the parasympathetic nervous system responsible for?

Answer 3

Returning the heart and respiratory rate back to normal resting levels during exercise.

Question 4

Where is the cardiac control centre?

Answer 4

In the medulla oblongata.

Question 5

What does the CCC control?

Answer 5

The heart rate

Question 6

How does the sympathetic nervous system increase heart rate?

Answer 6

It releases adrenaline.

Question 7

What does noradrenaline do?

Answer 7

Aids the spread of the impulse through the heart.

Question 8

When adrenaline is released it also increases the stroke volume. Why is this?

Answer 8

The adrenaline increases the strength of the ventricle contractions and therefore the stroke volume increases because more blood is being forced out.

Question 9

What does the parasympathetic nervous system release to decrease the heart rate?

Answer 9

Acetylcholine.

Question 10

What does acetylcholine do?

Answer 10

It slows down the impulses in the heart.

Question 11

What are the three main factors that determine the action of the CCC?

Answer 11

Neural factors
Hormonal factors
Intrinsic factors

Question 12

What ‘receptors’ are involved in the neural factors?

Answer 12

Proprioreceptors/Mechanoreceptors
Chemoreceptors
Baroreceptors

Question 13

What do proprioreceptors do?

Answer 13

They relay the amount of movement in the muscles to the CCC.

Question 14

What happens when the proprioreceptors detect movement?

Answer 14

It tells the CCC that they require a higher amount of oxygen in order to respire.

Question 15

What do chemoreceptors detect?

Answer 15

Changes in the pH of the blood.

Question 16

Where are chemoreceptors?

Answer 16

In the aorta.

Question 17

Where are proprioreceptors found?

Answer 17

In the muscles.

Question 18

What do the chemoreceptors tell the CCC to do?

Answer 18

To increase the heart rate to remove CO2 faster so that the blood pH returns to normal.

Question 19

What do baroreceptors detect?

Answer 19

Changes in blood pressure.

Question 20

Which hormones are involved in the hormonal factors of the CCC?

Answer 20

Adrenaline and noradrenaline.

Question 21

Adrenaline and noradrenaline increase the strength of contraction of the ventricles but they also….

Answer 21

Assisst the redistribution of blood through vasoconstriction and vasodilation.

Question 22

What increases in the body in terms of intrinsic factors?

Answer 22

Increase in body temperature during exercise.
Increase in blood viscosity/ability to travel around the body.
Raises heart rate by an increase in speed of nerve impulse transmission.

Question 23

At rest which nervous system is in control?

Answer 23

The parasympathetic nervous system.

Question 24

An increase in metabolic activity causes what?

Answer 24

Increase in the concentration of lactic acid and CO2.

A decrease in blood pH.

Question 25

Why does venous return increase during exercise?

Answer 25

It is a result of an increase in action of the muscle pump.

Question 26

What happens when blood pressure is too high?

Answer 26

The baroreceptors detect it and messages are sent from the cardiac inhibitory centre to the SA node via the vagus nerve. The PSNS releases acetylcholine which decreases the heart rate.