Control of heart rate

Question 1

What are the two parts to the nervous system?

Answer 1

Central nervous system

Peripheral nervous system

Question 2

What is the central nervous system made up of?

Answer 2

Brain

Spinal cord

Question 3

What is the peripheral nervous system made up of?

Answer 3

Somatic nervous system

Autonomic nervous system

Question 4

What does the somatic nervous system control?

Answer 4

conscious activities

Question 5

What is the autonomic nervous system made up of?

Answer 5

Sympathetic and parasympathetic

Question 6

What does the autonomic nervous system control?

Answer 6

Unconscious activities

Question 7

What does the sympathetic nervous system do?

Answer 7

controls the flight or fight response which gets the body ready for action
S for Stress

Question 8

What does the parasympathetic nervous system do?

Answer 8

Controls the ‘rest and digest’ which returns the body back to normal once the threat has passed

Question 9

Which nervous system is involved in the control of heart rate?

Answer 9

Autonomic nervous system

Question 10

What does myogenic mean?

Answer 10

The heart muscle can contract and relax without receiving signals from nerves

Question 11

What are the two nodes involved in the control of the heart beat?

Answer 11

Sinoatrial node (SAN) 
Atrioventricular node (AVN)

Question 12

Where is the sinoatrial node found?

Answer 12

In the wall of the right atrium

Question 13

What does the sinoatrial node do?

Answer 13

Sends out regular waves of electrical activity to the atrial walls which causes the right and left atria to contract at the same time

Question 14

What does the band of non-conducting collagen tissue do?

Answer 14

Prevents the waves of electrical activity from being passed directly from the atria to the ventricles

Question 15

Instead of going straight to the ventricles, where do the waves of electrical activity go from the atria?

Answer 15

To the atrioventricular node

Question 16

What is the atrioventricular node responsible for?

Answer 16

Passing the waves of electrical activity to the Bundle of His

Question 17

Why is there a slight delay in the AVN reacting to the electrical activity?

Answer 17

To make sure the atria have emptied before the ventricles contract

Question 18

What is the Bundle of His?

Answer 18

A group of muscle fibres responsible for conducting the waves of electrical activity between the ventricles to the apex of the heart

Question 19

What is purkyne tissue?

Answer 19

The finer muscle fibre branches from the Bundle of His in the right and left ventricle walls

Question 20

What is the purpose of the Purkyne tissue?

Answer 20

Carries the waves of electrical activity into the muscular walls of the right and left ventricles, causing them to contract simultaneously from the bottom up

Question 21

Why do animals need to alter their heart rate?

Answer 21

To response to internal stimulus to prevent fainting due to low blood pressure or make sure the heart rate is high enough to supply the body with enough oxygen

Question 22

What is the SAN controlled by?

Answer 22

the medulla in the brain

Question 23

What are baroreceptors?

Answer 23

Pressure receptors

Question 24

Where are baroreceptors found?

Answer 24

In the aorta and the carotid arteries

Question 25

What are baroreceptors stimulated by?

Answer 25

High and low blood pressures

Question 26

What are chemoreceptors?

Answer 26

Chemical receptors

Question 27

Where are chemoreceptors found?

Answer 27

In the aorta
In the carotid arteries
In the medulla

Question 28

What do chemoreceptors monitor?

Answer 28

Oxygen level in the blood

Carbon dioxide and pH

Question 29

Where does the medulla send information?

Answer 29

to the SAN along sympathetic or parasympathetic neurones

Question 30

What is the response when there is a high blood pressure?

Answer 30

1) Baroreceptors detect high blood pressure and sends impulses along sensory neurones to the medulla
2) medulla sends impulses along parasympathetic neurones
3) They secrete acetylcholine which bind to receptors on the SAN
4) This causes heart rate to slow down to reduce blood pressure

Question 31

What is the response when there is a low blood pressure?

Answer 31

1) Baroreceptors detect low blood pressure and sends impulses along sensory neurones to the medulla
2) The medulla sends impulses along the sympathetic neurones
3) They secrete noradrenaline which binds to receptors on the SAN
4) This causes the heart rate to speed up in order to increase blood pressure

Question 32

What is the response when there is a high blood O2, low CO2 or high blood pH levels?

Answer 32

1) Chemoreceptors detect chemical changes in the blood and send impulses along sensory neurones to the medulla
2) The medulla sends impulses along the parasympathetic neurones
3) They secrete acetylcholine which binds to receptors on SAN
4) this causes the heart rate to decrease in order to return oxygen, carbon dioxide and pH levels back to normal

Question 33

What is the response when there is a low blood O2, high CO2 or low blood pH levels?

Answer 33

1) chemoreceptors detect chemical changes in the blood and send impulses along sensory neurones to the medulla
2) The medulla sends impulses along the sympathetic neurones
3) They secrete noradrenaline which binds to receptors on the SAN
4) This causes the heart rate to increase in order to return oxygen, carbon dioxide and pH levels back to normal