Blood Vessels Flashcards

1
Q

what is the purpose of the elastic recoil of arteries?

A

to convert an intermittent flow to a continuous flow

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2
Q

what is the definition of elasticity?

A

reform its original shape after being stretched

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3
Q

what is the definition of complicance?

A

how easy it is to stretch a material

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4
Q

explain the mechanism of the wind Kessel effect?

A

systole stretches the artery walls due to the presence of elastin, and the walls being compliant
this transfers potential energy to the walls which recoil during diastole and keep the blood flow continuous, the cycle then repeats again

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5
Q

what is the ratio of elastin to collagen in elastic arteries?

A

more elastin than collagen

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6
Q

how do you calculate mean atrial blood pressure?

A

SP-DP/3 +DP

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7
Q

what is the equation for flow?

A

flow = change in pressure / resistance

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8
Q

give 5 main factors that effect blood pressure?

A

cardiac output, total peripheral resistance, elastic content of arterial walls, blood volume, blood viscosity

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9
Q

what is the aortic pulse pressure?

A

the maximum increase in aortic pressure from the time the valve opens until the peak aortic pressure

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10
Q

what are the main contributors of systolic pressure?

A

stroke volume, ejection velocity, arterial distensibility, diastolic pressure

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11
Q

what are the main contributors of diastolic pressure?

A

total peripheral resistance, arterial elasticity, heart rate

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12
Q

what are the risk factors for arteriosclerosis?

A

age (arteries lose elastin as we age), hypertension, smoking, diet

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13
Q

what is arteriosclerosis?

A

walls become thickened, lose elasticity as collagen to elastin ratio increases

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14
Q

what is atherosclerosis?

A

a subtype of arteriosclerosis where the walls thicken due / in conjunction with plaque build up

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15
Q

what are the 3 main factors that determine blood vessel resistance?

A

tube length, blood viscosity and radius

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16
Q

what effects blood viscosity?

A

haematocrit, therefore hypoxia and anaemia effect blood viscosity

17
Q

what is PAOD?

A

Peripheral arterial occlusive disease
narrowing or blockage of arteries that supply the extremities, particularly the lower limbs

18
Q

what can PAOD lead to?

A

stenosis, resulting in localised hypoxia and ischemic pain
particularly during exercise when metabolic demand can not be met

19
Q

what is lamina flow?

A

usual flow of arteries normal pattern of flow highly efficient and follows Poiseuille’s

20
Q

what is turbulent flow?

A

inefficient, high velocity flow, that is unordered doesn’t follow Poiseuille’s law

21
Q

what are the distinct histological features of large veins?

A

very thin tunica intima
moderate tunica media
extensive and large tunica adventitia containing elastin collagen and an extensive vasa vasorum
also large lumen

22
Q

where are continuous capillaries found?

A

lungs, CNS, adipose tissue

23
Q

where are fenestrated capillaries found?

A

in tissues with high exchange rates
e.g. kidneys, GI tract, endocrine glands

24
Q

where are discontinuous capillaries’ found?

A

liver, spleen, adrenal glands

25
Q

explain the structure of continuous capillaries

A

continuous layer of endothelial cells very tight junctions and a continuous basement membrane
substances move between intracellular clefts (gaps between endothelial cells)

26
Q

explain the structure of fenestrated capillaries

A

as well as intracellular cleft they have 60-80nm fenestrations (holes in cells)
thinner basement membrane than continuous

27
Q

explain the structure of discontinuous capillaries

A

large gaps in endothelial layer an basement membrane

28
Q

how is blood shut off to particular capillary beds?

A

pre capillary sphincters close off
blood is shunted through metarteriole

29
Q

where are the receptors in the capillary for transcytosis?

A

caveola (invagination’s of the lumen)

30
Q

why is starlings forces hypothesis for capillaries wrong?

A

the amount of fluid reabsorbed into the capillaries is less than expected
Protein permeability studies show that capillaries are not completely impermeable to proteins
Lymphatic flow is much higher than the classical hypothesis would suggest

31
Q

what are the complications of compressed tissues in oedema?

A

increased diffusion distance and extracellular fluid = slower diffusion
impaired cells trafficking
static fluid increases risk of infection
compression of nerves can lead to pain

32
Q

what are the 4 main causes of oedema?

A

hydrostatic oedema (hypertension)
oncotic oedema (loss of blood proteins e.g. loss of albumin in liver cirrhosis or more protein in interstitial fluid)
permeability oedema (increase in permeability, often found in inflammation)
prevention of drainage into lymph (increases interstitial hydrostatic pressure)

33
Q
A