Physiology: Baroreceptor Reflex for Short Term Control of MAP

Question 1

what is blood pressure

Answer 1

outwards pressure exerted by blood on blood vessel walls

Question 2

systolic bp + normal

Answer 2

when heart contracts

<140mmHg

Question 3

diastolic bp + normal

Answer 3

when heart relaxes

<90mmHg

Question 4

hypertension definition

Answer 4

clinical >140/90mmHg, daytime avg. 135/95mmHg

Question 5

pulse pressure + normal range

Answer 5

difference between systolic and diastolic bp 30-50mmHg

Question 6

MAP

Answer 6

avg. arterial bp during a single cardiac cycle

Question 7

estimating MAP + normal range

Answer 7

((2xdiastole)+systole) / 3
1/3 pulse pressure + diastolic
70-105mmHg

Question 8

a MAP of _ mmHg is needed to perfuse _

Answer 8

60

brain, kidneys and heart

Question 9

where are baroreceptors found

Answer 9

carotids and aorta

Question 10

how do carotid and aortic baroreceptors reach the brain

Answer 10

carotid - to medulla via CNIX

aortic - to medulla via CNX

Question 11

what type of receptors are barorecepetors and what are the sensitive to

Answer 11

mechano receptors

stretch

Question 12

draw the flow chart describing the different components of the baroreceptor reflex

Answer 12

**

Question 13

what happens to the firing rate in baroreceptor afferent neurons when MAP increases/decreases

Answer 13

MAP increases - firing increase

MAP decreases - firing decreases

Question 14

describe what happens to afferent impulses from baroreceptors

Answer 14

• CVS control centre (NTS) recieves afferent infro
• NTS then relays info to other parts of the brain
• vagal outflow generated and sent to nucelus ambigous in the medulla
• spinal sympathetic neurones regulated

Question 15

NTS

Answer 15

nucleus tract solitarus - 1st synapse for all CVS afferents in medulla (relays info)

Question 16

MAP = _ x _

Answer 16

CO x SVR

Question 17

CO

Answer 17

vol of blood pumped by each V per min

Question 18

CO = _ X _

Answer 18

SV x HR

Question 19

SV

Answer 19

vol of blood pumped by each V per heart beat

Question 20

SVR

Answer 20

sum of resistance in all systemic vasculature

Question 21

MAP can be regulated via regulation of

Answer 21

HR, SV, SVR

Question 22

autorhythmicity

Answer 22

beating rhythmically in absence of stimuli

Question 23

what does the ANS modify

Answer 23

HR

Question 24

the SNS acts through what to _ HR

Answer 24

• noradrenaline acting on beta1 receptors

- accelerates

Question 25

the PNS acts through what to _ HR

Answer 25

• CNX stimulation and ACh on muscarinic receptors

- slows

Question 26

SV increases if what increases and is regulated by

Answer 26

contractile strength, ANS

Question 27

the ventricular myocardium in innervated by

Answer 27

sympathetic nerves

Question 28

stimulation of ventricular S nerves increases what

Answer 28

force of contraction and therefore SV

Question 29

intrinsic control of SV is mainly regulated via what

Answer 29

Frank-Starling Mechanism

Question 30

what regulates SVR and what is the main site of SVR

Answer 30

SM and arterioles

Question 31

contraction of vascular SM _ SVR and MAP via _

Answer 31

increases via vasoconstriction

Question 32

relaxation of vascular SM _ SVR and MAP via _

Answer 32

decreases via vasodilation

Question 33

vascular SM are innervated by _ acting through _

Answer 33

S nerves, noradrenaline via alpha receptors

Question 34

vasomotor tone

Answer 34

vascular SM are partial constricted at resr due to tonic discharge by S nerves and continuous noradrenaline release

Question 35

what are the exceptions to no significant P innervation of arterial SM

Answer 35

penis and clitoris

Question 36

why cant baroreceptors maintain MAP long term

Answer 36

the ‘set point’ resets if there is a chronic change in MAP

- new steady state

Question 37

what controls MAP long term

Answer 37

hormonal control of blood vol

Question 38

draw thw flow chart describing all the changes in the baroreceptor reflex

Answer 38

**