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Human physiology > blood vessels and haemodynamics > Flashcards

blood vessels and haemodynamics Flashcards

1
Q

what does a circulatory system consist of?

A

fluid for transporting materials
tubes for the fluid to go through
a force to drive the fluid

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2
Q

how can you workout how fast something diffuses?

A

divide the time of diffusion by the diffusion coefficient

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3
Q

functions of circulation

A

maintain an optimal environment for cells

transport of nutrients, waste, hormones

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4
Q

artery function

A

blood away fro the heart in high pressure

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5
Q

capillary functions

A

exchange of nutrietns and waste between vessels and cells, interstitial fluid exchange

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6
Q

vessesl structures

A

adventitia
media
intima

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7
Q

what is the adventitia?

A

fibroblasts and fibrous elements gradually merge with surronding connective tissues
anchors the vessel in place providing mechaninical strength

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8
Q

what is the media?

A

elastic fibres, collagen fibres, confumferentially arranged smooth muscle
can contract and relax

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9
Q

what is the intima?

A

endothelial cells
surrounded by sub-endothelium and elastic fibres
barrier to prevent substances moving

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10
Q

what layer is larger in arteries?

A

media

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11
Q

what are the types of arteries?

A

elastic
muscular
terminal
arteroiles

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12
Q

whats an elastic artery

A

convert pulsatile flow into smoother continuous flow

closer to the heart

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13
Q

whats a muscular artery

A

smooth muscle and less elastic fibres

smaller and give divergence off elastic arties

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14
Q

whats terminal artery

A

add resistance and regular downstream flow

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15
Q

whats an ateriole

A

also resistance vessels

control the release of blood into capillaries

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16
Q

key features of veins?

A

thinner walls
large blood volume
valves present

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17
Q

what are th valves conected to?

A

the intima

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18
Q

whats a small vein>

A

venules

endothelial layer surrounded by longitudinal smooth muscle and occasional pericyte

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19
Q

how does blood move in veins?

A

they are typically positioned next to muscle pumps that squeeze the vessels pushing up the blood

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20
Q

what happens to blood velocity moving away from the heart?

A

drops
at same time surface area increases
when at the capillaries the velocity is at its lowest

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21
Q

what regulate capillary perfusion?

A

terminal arteries regulate the number of perfused capillaries

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22
Q

what is vasomotion?

A

indivivual terminal arteries cycle in contraction and relaxation
this is the time between open and close that determines the amount of blood flow in them

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23
Q

what is a capillary sphincter?

A

ring of muscle around capillaries which can reduce blood fow by contracting and restricting the flow downstream

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24
Q

what happens to capillary sphinceters under high oxygen

A

constrict

reducing flow

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25
Q

what happens to capillary sphincters under high carbon doxide

A

high metabolic rate
needs more oxygen
vessels open

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26
Q

what happens to capillary sphincters under low pH

A

high metabolic activity
high carbon dioxide
open vessels

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27
Q

what happens to capillary sphincerts under high body temp

A

vessesl open to move blood to the surface and reduce the temp

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28
Q

three capillary types?

A

continuous
fenestrated
discontinuous

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29
Q

features of a continuous capillary

A

highly selective barrier

30
Q

what is a caveola?

A

plasma membrane budds off into vesicle to move to inner lining to pass on substances
called caveola facilitated movement

31
Q

where are continuous capillaries found?

A

fat, muscle, nervous system

32
Q

features of a fenestrated capillary

A

thinner
porous membrane
permeable to small water soluble substrates

33
Q

where are fenestrated capillaries found?

A

intestinal wall vili
endocrine system glands
kidney glomeruli

34
Q

features of discontinuous capillaries

A

also called sinusoids
have large gaos in them
less selective as there are large gaps within

35
Q

where are discontinuous capillaries/ sinusoids found?

A

liver
bone marrow
spleen

36
Q

what is a pericyte?

A

cells like stem cells that are dormant around vesses

when there is damage they proliferate to help repair the vessel

37
Q

how is the circulatory system regulated?

A

hydrostatic pressure

osmotic pressure

38
Q

what is hydrostatic pressure?

A

the pressure the system exerts by the volume of blood when its confined within a vessel
it pushes fluid out of things

39
Q

what is osmotic pressure

A

the pressure exerted by the flow of liquid through a semi-permeable membrane separating two solutions with different concentrations of solutes

40
Q

what causes fluid to leak out?

A

higher hydrostatic pressure than osmotic

41
Q

what causes fluid to seep in?

A

higher osmotic pressure than hydrostatic

42
Q

where do hydrostatic and osmotic pressures need to be balanced?

A

at the arteriole end

43
Q

what does darcy’s law say about blood flow?

A

flow is proportional to pressure difference
no pressure difference means no flow
flow occurs from high to low pressure

44
Q

what is laminar flow?

A

The what’s condition for blood flow throughout most of the circulatory system.

45
Q

how is laminar flow characterised?

A

It is characterized by concentric layers of blood moving in parallel down the length of a blood vessel. The highest velocity (Vmax) is found in the center of the vessel.

46
Q

where is laminar flow found?

A

arteries
arteioles
veins
venules

47
Q

what is turbulet flow?

A

pressure difference above a critical point flow transitions to turbulent flow:
blood does not flow linearly and smoothly in adjacent layers, but instead the flow can be described as being chaotic
the flow now increases as a square root of the pressure difference

48
Q

where is turbulent flow found?

A

behind heart ventricles

49
Q

what is single file blood flow?

A

the diameter of most capillaeires is less than that of RCB

all RBC line up in single file touching all walls

50
Q

what reduced friction in single file blood flow

A

Friction between RBC and wall minimised by glycocalyx/thin film of plasma

51
Q

why is single file blood flow used?

A

efficient transport to surrounding tissues as RBC touches all walls of the capillary

52
Q

at rest which organ gets the most blood flow?

A

kidneys

53
Q

at rest which organ gets the least blood flow

A

skin

54
Q

at rest how much of cardiac output goes to the skeletal muscles?

A

20%

55
Q

what does Poiseuille’s law describe?

A

the dependence of the vessel diameter

flow is proportional to area and increased area gives more force

56
Q

what happens to resistance of blood vesles is series?

A

it adds up:

R1+R2=R

57
Q

what happens to resistance of blood vessels in paralet?

A

1/R= 1/R1 + 1/R2

58
Q

what controls blood flow?

A

arterioles

59
Q

what does widespread contraction lead to

A

increase in peripheral resitance and blood pressure

60
Q

what intrinsic factors control blood flow?

A 
local factors such as temp
myogenic response
vasodilator metabolites
endothelial factors
local hormones
61
Q

what extrinsic factors control blood flow?

A

hormones, nerve stimulation
vasoconstrctors
these can override intrinsic

62
Q

what is metabolic hyperaemia?

A

s the increase of blood flow to different tissues in the body

63
Q

what can cause metabolic hyperaemia?

A 
Co2
lactic acid
adenisine
potassion
phosphate
osmolarity
64
Q

what is intrinsic hyperaemia?

A

after exercise, blood flow to a muscle reamins elevated for a while

65
Q

why does flow to muscles after exercise remain high for a while?

A

build up of vasodilator metabolites, protagladins and NO

66
Q

what is nitric oxide?

A

diatomic free radical
lipid soluble and small, can pass through membranes
short lived

67
Q

how is nitric oxide synthesised?

A

from L-argenine

68
Q

how does NO cause smooth muscle relaxation?

A
  • stress stimulated by endothelial NO production
  • estrogens up regulate synthesis of NO
    inflammatory mediators increase NO also
    leading to relaxation
69
Q

what causes smooth muscle contraction?

A

mechanical stretching
electrical depolarisation
hormones

70
Q

how does smooth muscle contract?

A
  1. ixtracellular calcium increase, triggers release from sarcoplasmic reticulum
  2. Ca binds to calmodulin
  3. activated myosin light chain kinase ( MLCK)
  4. MLCK phosphorylatates heads of myosin increasing ATPase activity
  5. active myosin chrossbridges slide along actin creating muscel tension
71
Q

how does smooth muscle relax?

A
  1. free Ca in ctosol decreases its pumped back out or into sarcoplasmic reticulum
  2. Ca unbinds from calmodulin, CaM
  3. myosin phophatase removes phosphate from moysin decreasing ATPase activity
  4. less myosin ATPase reseults in decreased muscle tension

Human physiology (21 decks)

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