Baroreceptor Reflex - Regulation Of Mean Arterial Blood Pressure

Question 1

What is blood pressure

Answer 1

The outwards (hydrostatic) pressure exerted by blood on blood vessel walls

Question 2

What type of blood pressure is measured in clinical practice

Answer 2

Systemic arterial blood pressure

Question 3

What is systolic arterial blood pressure

Answer 3

pressure from left ventricle contracting

Question 4

What is diastolic arterial blood pressure

Answer 4

The pressure exerted by the blood on the walls of the aorta and systemic arteries during relax

Question 5

What blood pressure values indicate hypertension

Answer 5

Clinic blood pressure of 140/90mmHg or higher

Question 6

What is pulse pressure

Answer 6

Difference between systolic and diastolic blood pressures
Normal range 30-50mmHg

Question 7

What is mean arterial blood pressure (MAP)

Answer 7

Average arterial blood pressure during a single cardiac cycle (systole and diastole)

Question 8

Why is MAP not obtained by averaging systolic and diastolic pressures

Answer 8

Diastole lasts twice as long as systole

Question 9

How is MAP estimated

Answer 9

(2x diastole pressure + systolic pressure) 3

Question 10

Secondary method to estimating MAP

Answer 10

Diastolic BP + 1/3 pulse pressure

Question 11

Normal MAP range

Answer 11

70-105mmHg

Question 12

What MAP value is needed to perfuse vital organs

Answer 12

Minimum 60mmHg

Question 13

What happens if MAP value is too high

Answer 13

Damage blood vessels
Place an extra strain on heart and other organs

Question 14

What path do signals take during negative feedback

Answer 14

Detected by sensor (when not in narrow range)
Informs control centre
Sends instruction to effectors
Brings about compensatory results

Question 15

What is the sensor used to regulate MAP

Answer 15

Baroreceptors

Question 16

What is the cardiovascular control centre

Answer 16

Medulla

Question 17

What are the effectors of the MAP

Answer 17

Heart - varies HR and SV
Blood vessels

Question 18

How do blood vessels work to get MAP back to narrow range

Answer 18

By varying systemic vascular resistance

Question 19

Which baroreceptors inform the medulla

Answer 19

Carotid baroreceptors
Aortic arch baroreceptors

Question 20

What type of receptor are baroreceptors

Answer 20

Mechanoreceptors sensitive to stretch, the more stretch the more signals are fired

Question 21

What cause the firing rate in baroreceptor afferent (outgoing) neurons to increase

Answer 21

When MAP increases

Question 22

Where do baroreceptors send afferent impulses to

Answer 22

The cardiovascular control centre in the medulla of the brainstem

Question 23

What is the role of the NTS in regulating MAP

Answer 23

Integrates and relays information to other regions that control pathways for the sympathetic and parasympathetic nervous system for the heart and blood vessels

Question 24

What is stroke volume

Answer 24

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

Question 25

What is cardiac output

Answer 25

The volume of blood pumped by each ventricle per minute

Question 26

What is the relationship between MAP, CO and SVR (systemic vascular resistance)

Answer 26

MAP = CO X SVR

Question 27

What is systemic vascular resistance

Answer 27

Sum of resistance of all vasculature in the systemic circulation

Question 28

What are the 3 ways MAP can be regulated

Answer 28

Heart rate Stroke volume Systemic vascular resistance

Question 29

What term is used to describe the heart beating in absence of external stimuli

Answer 29

Autorhythmicity

Question 30

What does the sympathetic division in the heart result in

Answer 30

Stimulation accelerates heart rate Releases noradrenaline acting on beta1 receptors

Question 31

What does the parasympathetic division of the ANS stimulate

Answer 31

Vagus nerve which slows the heart rate Acetylchlorine acts on M2 receptors

Question 32

How is stroke volume increased

Answer 32

If contractile strength of heart is increased

Question 33

How is the contractile strength of the heart increased

Answer 33

Sympathetic nerves (found in myocardium) increases the force of contraction hence stroke volume

Question 34

Which blood vessel shows the most resistance

Answer 34

Arterioles, pressure decreases when passing through due to smooth muscle layer

Question 35

Which type of nerve fibre supplies the vascular smooth muscle

Answer 35

Sympathetic

Question 36

Which type of neurotransmitters acts on the alpha receptors of the sympathetic nerves

Answer 36

Noradrenaline

Question 37

What causes the vasomotor tone of vascular smooth muscle

Answer 37

Tonic discharge or sympathetic nerves resulting in continuous release or noradrenaline

Question 38

What happens if there is a decrease in sympathetic discharge

Answer 38

Decrease in vasomotor tone resulting in vasodilation causing a decrease in MAP and SVR

Question 39

When does baroreceptor firing decrease

Answer 39

If high arterial blood pressure is sustained