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CV System > Vasculature Physiology > Flashcards

Vasculature Physiology Flashcards

1
Q

When is turbulent flow likely to occur?

A

rate of flow becomes too great, makes a sharp turn, incurs obstruction, abnormal vessel walls, low viscocity and large diameter vessles

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2
Q

formation of what adds overall friction to turbulent flow?

A

eddy currents

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3
Q

what is the purpose of reynolds number?

A

indicates whether flow is likely to be laminar or turbulent

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4
Q

how is reynolds number calculated what is the significance of the critical value?

A

(velocity of flow x radius of vessel)/viscocity

above the critical value turbulence is likely

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5
Q

at what number will turbulence occur in branching but not smooth parts of a vessel?

A

200-400

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6
Q

at what number will turbulence definitely occur?

A

2000

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7
Q

what is a thixotropic fluid?

A

flow of fluid affects the viscocity of fluid

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8
Q

what causes the sounds heard in BP measurements?

A

the jetting of blood though a partially occluded vessel

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9
Q

what is laplaces law, how is it calculated and what is its significance?

A

distending pressure produces an opposing force or tension in the vessel wall
tension = distending pressure x radius
small radius normalises tension

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10
Q

why do aneurysms occurs?

A

walls of large arteries cannot constrict to normalise the tension produced by distending flow

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11
Q

what is the purpose of arterioles?

A

control regional distribution of blood

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12
Q

what is the purpose of metarterioles?

A

link arterioles to veins

formed of discontinuous smooth muscle cells

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13
Q

where are precapillary sphincters found?

A

where a true capillary branches from a metarteriole

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14
Q

what is hyperaemia?

A

regulation of blood flow controlled by local factors associated with metabolic activity of tissues

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15
Q

what is and when does reactive hyperaemia occur?

A

following occlusion of blood supply
blood flow increase 4-7x for a time proportional to time occluded
repays oxygen debt

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16
Q

what is and when does active hyperaemia occur?

A

increase in blood flow caused by increase in metabolic activity
mediated by large quantities of vasodilators which are the waste product of metabolism

17
Q

what is flow autoregulation

A

change in flow in response to changes in arterial pressure

increase in pressure causes vasoconstriction to oppose flow

18
Q

what mechanism mediates flow autoregulation

A

myogenic stretch response by stretch activated Ca2+ channels

19
Q

what is vasomotion

A

the intermittent contraction of meta-arterioles and precapillary sphincters

20
Q

what regulation of flow mechanism is related to response to injury

A

release of endothelium-1 by damaged endothelium cells

potent vasoconstriction to prevent bleeding

21
Q

what is the role of NO

A

released during stress by endothelium to decrease resistance

22
Q

how is NO synthesised by endothelial cells?

A

eNOS enzymes

ardinine and oxidation through reduction of inorganic nitrate

23
Q

what hormone will trigger NO synthesis

A

angiotensin II - prevents excess vasoconstriction

24
Q

how much CO is found in capillaries

A

5%

25
Q

what are some local (metabolic) factors of vasodilation

A

adenosine,hydrogen ions, potassium

26
Q

how is local blood flow regulated in the long term

A

change in physical size and number of blood vessels

27
Q

name some hormonal vasocontrictors

A

adrenaline
angiotensin II
vasopressin

28
Q

name some local vasoconstrictors

A

endothelin-1

myogenic stretch response

29
Q

name some hormonal vasodilators

A

adrenaline

atrial naturetic peptide

30
Q

name some local vasodilators

A

decrease in O2
NO
bradykinin

31
Q

what are the different kinds of capillaries

A

fenestrated
continous
sinusoid or discontinuous

CV System (18 decks)

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