Feedback control in the cardiovascular system

Question 1

What is measured when blood pressure is taken?

Answer 1

The systemic arterial blood pressure during systole and diastole

Question 2

What is systemic systolic arterial blood pressure?

Answer 2

The outwards, hydrostatic pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart contracts

Question 3

What is systemic diastolic arterial blood pressure?

Answer 3

The outwards, hydrostatic pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart relaxes

Question 4

What is the ideal systolic arterial blood pressure range for a person under 80?

Answer 4

90-120 mmHg

Question 5

What is the ideal diastolic arterial blood pressure range for a person under 80?

Answer 5

60-80 mmHg

Question 6

What clinic blood pressure is defined as hypertension?

Answer 6

140/90 mmHg or higher

Question 7

What day time average pressure is defined as hypertension?

Answer 7

135/85 mmHg or higher

Question 8

What is pulse pressure?

Answer 8

The difference between systolic and diastolic blood pressures

Question 9

What is the ideal pulse pressure range?

Answer 9

30-50 mmHg

Question 10

What is mean arterial blood pressure (MAP)?

Answer 10

The average arterial blood pressure during a single cardiac cycle, which involves systole and diastole

Question 11

Why is the mean arterial blood pressure not the value half way between systolic and diastolic blood pressure?

Answer 11

Because during the cardiac cycle, the diastolic portion is twice as long as the systolic

Question 12

How do you calculate mean arterial blood pressure?

Answer 12

MAP=(2D+S)/3, where S is systolic pressure and D is diastolic

Question 13

What is the ideal mean arterial blood pressure range?

Answer 13

70-105 mmHG

Question 14

What is the minimum mean arterial blood pressure required to perfuse vital organs such as the brain?

Answer 14

60 mmHg

Question 15

Why can blood pressure not get too high?

Answer 15

If pressure is too high, blood vessels can become damaged and extra strain can be placed on the heart and other vital organs such as the brain or kidneys

Question 16

What type of receptor detects changes in blood pressure?

Answer 16

Baroreceptors

Question 17

What is the control centre within the brain for blood pressure?

Answer 17

The medulla oblongata

Question 18

What are the 2 main types of baroreceptors?

Answer 18

Carotid and aortic baroreceptors

Question 19

What nerve carries impulses from the aortic baroreceptors to the medulla oblongata?

Answer 19

The vagus nerve (the 10th cranial nerve)

Question 20

What nerve carries impulses from the carotid baroreceptors to the medulla oblongata?

Answer 20

The Hering’s nerve, which is a branch of the glossopharyngeal nerve (the 9th cranial nerve)

Question 21

What kind of receptors are baroreceptors?

Answer 21

They are mechanoceptors that are sensitive to stretch

Question 22

How does an increase in mean arterial blood pressure affect the firing rate of a baroreceptor?

Answer 22

The firing rate increases

Question 23

How does a decrease in mean arterial blood pressure affect the firing rate of a baroreceptor?

Answer 23

The firing rate decreases

Question 24

What is the site of first synapse for all cardiovascular system afferents in the medulla?

Answer 24

The nucleus tractus solitarius

Question 25

What is the function of the nucleus tractus solitarius?

Answer 25

It integrates and relays information to other regions that control the pathways of the two divisions of the autonomic nervous system to the heart and blood vessels

Question 26

What is the formula for MAP using cardiac output and systemic vascular resistance?

Answer 26

MAP= CO x SVR

Question 27

What is the formula for cardiac output using stroke volume and heart rate?

Answer 27

CO = SV x HR

Question 28

What is the formula for MAP using stroke volume, heart rate and systemic vascular resistance?

Answer 28

MAP = SV x HR x SVR

Question 29

What is cardiac output?

Answer 29

The volume of blood pumped out by each ventricle per minute

Question 30

What is stroke volume?

Answer 30

The volume of blood pumped out by each ventricle per heart beat

Question 31

What is systemic vascular resistance?

Answer 31

The sum of resistance of all vasculature in the systemic circulation

Question 32

What is autorhymicity?

Answer 32

The capability of the heart to beat rhythmically in the absence of an external stimuli

Question 33

What does stimulation of the sympathetic division cause?

Answer 33

Tachycardia

Question 34

What is tachycardia?

Answer 34

Acceleration of the heart rate

Question 35

What does stimulation of the parasympathetic division cause?

Answer 35

Bradycardia

Question 36

What is bradycardia?

Answer 36

Deceleration of the heart rate

Question 37

What nerve is stimulated in the parasympathetic division to cause bradycardia?

Answer 37

The vagus nerve

Question 38

What neurotransmitter is present in the sympathetic division and causes bradycardia?

Answer 38

Noradrenaline (norepinephrine)

Question 39

What type of receptors does noradrenaline act on during bradycardia?

Answer 39

ß1 receptors in the heart

Question 40

What neurotransmitter is present in the parasympathetic division and causes tachycardia?

Answer 40

Acetylcholine

Question 41

What type of receptor does acetylcholine act on during tachycardia?

Answer 41

Muscarinic (M2) receptors in the heart

Question 42

How does stimulation of the sympathetic division affect stroke volume?

Answer 42

Stroke volume increases as the contractile strength of the heart increases.

Question 43

How does the sympathetic nerve increase the contractile strength of the heart?

Answer 43

Sympathetic nerves innervate the ventricular myocardium and stimulation increases the force of contraction

Question 44

How does intrinsic control of stroke volume occur?

Answer 44

Through the Frank-Starling mechanism

Question 45

What vessel is the main site of systemic vascular resistance?

Answer 45

The arterioles

Question 46

What causes an increase in SVR and MAP?

Answer 46

Contraction of smooth muscle causing vasoconstriction

Question 47

What causes a decrease in SVR and MAP?

Answer 47

Relaxation of smooth muscle causing vasodilation

Question 48

What causes the vasomotor tone?

Answer 48

The tonic discharge of sympathetic nerves, resulting in continuous release of noradrenaline

Question 49

How does the sympathetic division increase SVR?

Answer 49

Sympathetic nerve fibres stimulate contraction of vascular smooth muscle

Question 50

What neurotransmitter is released by sympathetic nerve fibres during vasoconstriction?

Answer 50

Noradrenaline

Question 51

What receptor does noradrenaline act upon during vasoconstriction?

Answer 51

α receptors

Question 52

What is the name given to the partial constriction of smooth muscle when at rest?

Answer 52

The vasomotor tone

Question 53

What effect does increased sympathetic stimulation have on the vasomotor tone?

Answer 53

The vasomotor tone will increase, therefore causing vasoconstriction

Question 54

What effect does decreased sympathetic stimulation have on the vasomotor tone?

Answer 54

The vasomotor tone will decrease, therefore causing vasodilation

Question 55

Where in the body is there parasympathetic innervation of arterial smooth muscle?

Answer 55

The penis and clitoris

Question 56

What happens to the firing rate of baroreceptors if high arterial blood pressure is sustained?

Answer 56

It decreases and baroreceptors reset and will only fire again if an MAP is detected above the new high level