6.1.3 Control of Heart Rate

Question 1

Describe and explain the process that involves the control of the cardiac cycle and heart rate

Answer 1

• SAN sends wave of electrical impulses to AVN, causing atrial contraction
• Non-conducting tissue prevents the electrical impulse reaching the ventricles, preventing the immediate contraction of ventricles
• The AVN delays sending a wave to electrical impulses, to allow the ventricles to fill completely with blood
• The AVN sends a wave of electrical impulses down the Bundle of His and Purkyne fibres
• This causes the ventricles to contract from the base-up

Question 2

What does the SAN sending a wave of electrical impulses to the AVN cause

Answer 2

Atrial contraction

Question 3

Purpose of non-conducting tissue

Answer 3

Prevent electrical impulses reaching the ventricles, preventing the immediate contraction of ventricles

Question 4

What does the AVN sending electrical impulses down the Bundle of His and Purkinje fibres cause

Answer 4

Ventricles to contract from base-up

Question 5

Describe how the impact of heavy exersice is controlled by the cardiac cycle

Answer 5

• Rate of aerobic respiration increases, producing more carbon dioxide, lowering blood pH
• Chemoreceptors in carotid artery detect the decrease in blood pH
• Chemoreceptors send a wave of electrical impulses to the medulla
• The medulla sends more electrical impulses to the SAN, via the sympathetic nervous system
• More waves of electrical impulses sent from SAN to AVN

Question 6

If heart rate was to increase, down what autonomic nervous sytem would waves of electrical impulses be sent down

Answer 6

Sympathetic

Question 7

If heart rate was to decrease, down what autonomic nervous sytem would waves of electrical impulses be sent down

Answer 7

Parasympathetic

Question 8

What receptors detect blood pH and where are they located

Answer 8

Chemoreceptors in the carotid artery

Question 9

What part of the brain controls nervous activity as part of the cardiac cycle

Answer 9

Medulla

Question 10

Describe the impact that high blood pressure has on heart rate and the cardiac cycle

Answer 10

• Baroreceptors in the carotid artery detect the high blood pressure
• Baroreceptors sends waves of electrical impulses to the medulla
• The medulla sends more waves of electrical impulses to the SAN, via the parasympathetic nervous system
• Less waves of electrical impulses are sent from the SAN to the AVN

Question 11

What receptors detect blood pressure and where are they located

Answer 11

Baroreceptors in the carotid artery

Question 12

What nervous systems are contained in the autonomic nervous system

Answer 12

Sympathetic and parasympathetic

Question 13

The control of the cardiac cycle is regulated by which nervous system

Answer 13

Autonomic