vascular function

Question 1

describe reactive hyperaemia

Answer 1

• linkage between metabolism and blood flow
• occurs after a BV is occluded for a short period
• when the occlusion is released, BF rises above the pre-occlusion level and this hyperaemia is maintained for a period of roughly proportional to duration of occlusion

Question 2

post capillary vessels vs pre-capillary vessels

Answer 2

post-capillary have a smaller proportion of vascular SM than pre-capillary vessels of same generation

Question 3

architecture of small arteries and arterioles

Answer 3

• high proportion of vascular SM in walls

Question 4

myogenic hypothesis

Answer 4

• increased perfusion pressure increases vascular pressures throughout the circulation
• increased transmural P leads to vascular distention
• stretch elicits SM contraction

Question 5

describe release of nitric oxide

Answer 5

• intrinsic to endothelium
• gaseous, so distributes rapidly
• increased BF -> increased shear stress -> NO release -> vasodilation

Question 6

distribution of sympathetic innervation

Answer 6

• sympathetic adrenergic nerves supply all vascular beds in the body
• sympathetic nerves terminals distributed in pre- and post-capillary vessels
• extent of sympathetic innervation of circulation varies among organ systems

Question 7

describe cholinergic nerves and the effect of damaged endothelium

Answer 7

• innervation of BVs is largely parasympathetic
• activation of nerves = ACh in bloodstream
• ACh binds to M3 receptors in BVs -> NO -> vasodilation

damaged endothelium means no binding to M3 and ACh acts directly on muscarinic receptors in SM = vasoconstriction

Question 8

noradrenaline decreases flow to

Answer 8

• skeletal muscle flow
• skin flow
• kidney flow
• splanchnic flow

Question 9

adrenaline increased and decreased effect

Answer 9

increased

• skeletal muscle flow
• splanchnic flow

decreased

• skin flow
• kidney flow

Question 10

affinity for alpha receptors

Answer 10

EP > NEP > isoprenaline

Question 11

affinity for beta 2 receptors

Answer 11

isoprenaline > EP > NEP

Question 12

describe cerebral circulation

Answer 12

• autoregulation over perfusion pressure range 60-180mmHg
• cerebral BF regulated dominantly by local factors
• perivascular pH and pCO2, pO2, and K important vasodilator metabolites

Question 13

describe skin circulation

Answer 13

• affinity of a receptor for NA decreases with local temp (vice versa)
• sympathetic cholinergic activation of sweat glands activates kinin cascade
• bradykinin dilates precapillary vessels, constrict postcapillary vessels and increase capillary permeability

Question 14

inhibitory modulation of adrenergic neurotransmission

Answer 14

• ACh
• adenosine
• histamine
• PG E1 & E2

circulating adrenaline acts on precapillary B2 receptors

Question 15

excitatory modulation of adrenergic transmission

Answer 15

• angiotensin 2

- adrenaline