Special Circulations

Question 1

what are the 3 adaptions of the coronary circulation

Answer 1

• high capillary density
• high basal blood flow
• high O2 extraction

Question 2

what are the 3 responses to changes in coronary blood flow

Answer 2

• arteriolar vasodilation in response to decreased pO2
• metabolic hyperaemia, to match flow to demand
• vasodilation in response to adenosine release

Question 3

what type of nerve supply do coronary arteries have

Answer 3

sympathetic vasoconstrictor nerves

Question 4

what can override the coronary arteries sympathetic innervation

Answer 4

metabolic hyperaemia

Question 5

what is metabolic hyperaemia due to

Answer 5

increased HR and SV

Question 6

what does sympathetic stimulation of coronary arteries cause

Answer 6

vasodilation

Question 7

what does sympathetic stimulation usually cause

Answer 7

vasoconstriction

Question 8

what does circulating adrenaline activate

Answer 8

beta2 adrenergic receptors

Question 9

what does stimulation of the beta 2 adrenergic receptors cause

Answer 9

vasodilation

Question 10

draw the ‘Coronary Blood Flow’ flow chart

Answer 10

diagram

Question 11

when does most of the left coronary blood flow happen

Answer 11

diastole

Question 12

increased heart rate shortens _ and can result in decreased _ _ _

Answer 12

diastole

coronary blood flow

Question 13

when does most coronary blood flow and myocardial perfusion occur

Answer 13

diastole

Question 14

what vessels supply the brain

Answer 14

internal carotids and vertebral arteries

Question 15

what part of the brain is sensitive to hypoxia

Answer 15

grey matter

Question 16

if grey matter is ischaemic for a few seconds what happens

Answer 16

loss of consciousness

Question 17

if grey matter is ischaemic for ~3 minutes what happens

Answer 17

irreversible cell damage

Question 18

what arteries anastomose to form the circle of willis

Answer 18

carotid and basilar

Question 19

what forms basilar arteries

Answer 19

2 vertebral arteries

Question 20

what arises from the circle of willis

Answer 20

major cerebral arteries

Question 21

what is the function of the circle of willis

Answer 21

if one carotid artery is obstructed then cerebral perfusion maintains

Question 22

what happens if one small branch of a main artery of the circle of willis is blocked

Answer 22

deprive a region of the brain of blood

Question 23

what is a stroke caused by

Answer 23

cut off/interruption of blood supply to a region of the brain

Question 24

what can arteries be obstructed by

Answer 24

• emboli
• haemorrhage
• atherosclerosis

Question 25

what range does auto-regulation of cerebral blood flow work within

Answer 25

60-160mmHg