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Human physiology > blood vessels and haemodynamics > Flashcards

blood vessels and haemodynamics Flashcards

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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
what happens to capillary sphincters under high carbon doxide
high metabolic rate needs more oxygen vessels open
26
what happens to capillary sphincters under low pH
high metabolic activity high carbon dioxide open vessels
27
what happens to capillary sphincerts under high body temp
vessesl open to move blood to the surface and reduce the temp
28
three capillary types?
continuous fenestrated discontinuous
29
features of a continuous capillary
highly selective barrier
30
what is a caveola?
plasma membrane budds off into vesicle to move to inner lining to pass on substances called caveola facilitated movement
31
where are continuous capillaries found?
fat, muscle, nervous system
32
features of a fenestrated capillary
thinner porous membrane permeable to small water soluble substrates
33
where are fenestrated capillaries found?
intestinal wall vili endocrine system glands kidney glomeruli
34
features of discontinuous capillaries
also called sinusoids have large gaos in them less selective as there are large gaps within
35
where are discontinuous capillaries/ sinusoids found?
liver bone marrow spleen
36
what is a pericyte?
cells like stem cells that are dormant around vesses | when there is damage they proliferate to help repair the vessel
37
how is the circulatory system regulated?
hydrostatic pressure | osmotic pressure
38
what is hydrostatic pressure?
the pressure the system exerts by the volume of blood when its confined within a vessel it pushes fluid out of things
39
what is osmotic pressure
the pressure exerted by the flow of liquid through a semi-permeable membrane separating two solutions with different concentrations of solutes
40
what causes fluid to leak out?
higher hydrostatic pressure than osmotic
41
what causes fluid to seep in?
higher osmotic pressure than hydrostatic
42
where do hydrostatic and osmotic pressures need to be balanced?
at the arteriole end
43
what does darcy's law say about blood flow?
flow is proportional to pressure difference no pressure difference means no flow flow occurs from high to low pressure
44
what is laminar flow?
The what's condition for blood flow throughout most of the circulatory system.
45
how is laminar flow characterised?
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
where is laminar flow found?
arteries arteioles veins venules
47
what is turbulet flow?
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
where is turbulent flow found?
behind heart ventricles
49
what is single file blood flow?
the diameter of most capillaeires is less than that of RCB | all RBC line up in single file touching all walls
50
what reduced friction in single file blood flow
Friction between RBC and wall minimised by glycocalyx/thin film of plasma
51
why is single file blood flow used?
efficient transport to surrounding tissues as RBC touches all walls of the capillary
52
at rest which organ gets the most blood flow?
kidneys
53
at rest which organ gets the least blood flow
skin
54
at rest how much of cardiac output goes to the skeletal muscles?
20%
55
what does Poiseuille's law describe?
the dependence of the vessel diameter | flow is proportional to area and increased area gives more force
56
what happens to resistance of blood vesles is series?
it adds up: | R1+R2=R
57
what happens to resistance of blood vessels in paralet?
1/R= 1/R1 + 1/R2
58
what controls blood flow?
arterioles
59
what does widespread contraction lead to
increase in peripheral resitance and blood pressure
60
what intrinsic factors control blood flow?
``` local factors such as temp myogenic response vasodilator metabolites endothelial factors local hormones ```
61
what extrinsic factors control blood flow?
hormones, nerve stimulation vasoconstrctors these can override intrinsic
62
what is metabolic hyperaemia?
s the increase of blood flow to different tissues in the body
63
what can cause metabolic hyperaemia?
``` Co2 lactic acid adenisine potassion phosphate osmolarity ```
64
what is intrinsic hyperaemia?
after exercise, blood flow to a muscle reamins elevated for a while
65
why does flow to muscles after exercise remain high for a while?
build up of vasodilator metabolites, protagladins and NO
66
what is nitric oxide?
diatomic free radical lipid soluble and small, can pass through membranes short lived
67
how is nitric oxide synthesised?
from L-argenine
68
how does NO cause smooth muscle relaxation?
- stress stimulated by endothelial NO production - estrogens up regulate synthesis of NO inflammatory mediators increase NO also leading to relaxation
69
what causes smooth muscle contraction?
mechanical stretching electrical depolarisation hormones
70
how does smooth muscle contract?
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
how does smooth muscle relax?
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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