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PHGY 210 > cardiovascular - lecture 3 > Flashcards

cardiovascular - lecture 3 Flashcards

1
Q

HOW DOES flow move

A

higher pressure to lower pressure

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2
Q

what is blood pressure

A

force exerted by blood on wall of bv
blood flow = higher to lower pressure
pressure needed for blood flow

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3
Q

what is pressure

A

force/area

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4
Q

what is systemic bp

A

120/80mmhg

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5
Q

what is central venous pressure

A

5-15 cm h2o (6-12mmhg)

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6
Q

when is there no flow

A

when force = pressurexarea is equal on both sides
no diff in pressur e

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7
Q

when is there flow

A

p inlet
p outlet
diff pressures =flow

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8
Q

describe flow in capillaries

A

decrease velocity and pressure = stop from pushing things out through membranes
like at kidneys

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9
Q

describe pressure in blood vessels

A

increased in arteries and arterioles than in cap, venules and veins
resistance much greater in arteries and arterioles than in cap
arteries and arterioles = high resistance and cap and veins and venules = low resistance
more muscle = contract better, structure is everything

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10
Q

describe pressure - pulm circ gen

A

systemic = high
diastolic = low
less significant in smaller vessels, less and less since further away
much easier than whole periphery
pressure lower in pulm circ since small distance

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11
Q

describe diff between systolic and diastolic

A

pressures higher during systole than diastole
oscillations between the 2 parts of the cardiac cycle

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12
Q

is pressure differences between systole and diastole important in all bv

A

NOOOO
less significant for arterioles and cap
important for arteries, arterioles and cap

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13
Q

is the oscillation of pressure between the 2 parts of the cycle present all the time

A

NOO
dissapears in veins and venules

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14
Q

what is perfusion pressure

A

perfusion pressure = inlet pressure -outlet pressure
delta P = Pin - Pout
what goes in - what goes out

arterial pressure - venous pressure
but normally Pa&raquo_space; Pv (100mmhg vs 5mmhg)
so delta P is around Pa

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15
Q

when is there no flow - perfusion pressure

A

when delta P = 0
not flowing, static
Pin=Pout

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16
Q

what is flow formula

A

perfusion pressure/resistance

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17
Q

which vessel regulates flow

A

arteries
can change diameter

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18
Q

what is hypertension

A

more resistance so bp increases

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19
Q

what is flow proportional to

A

perfusion pressure
which is approx equal to arterial pressure

20
Q

what is resistance

A

resistance = perfusion pressure/flow
force that opposes movement

21
Q

what is friction

A

occurs between vessel wall and blood

22
Q

what happens when increased vessel length

A

increases surface= increased resistance

23
Q

describe friction and vessel lentgh

A

more resistance and small flow when longer

24
Q

describe friction and vessel luminal diameter

A

greatest resistance near surface, slowest flow, more friction
least resistance at center, greatest flow
fluid speed greater in middle of cylinder than at the walls

25
Q

what is laminar flow

A

entire fluid flows in same dir
opposed to turblent flow (ex = athersclerosis, wont be straight flow v turbulent since plaques)

26
Q

what depends on viscosity

A

the flow speed

27
Q

what is viscosity

A

friction between moving molecules
greater the friction = greater the viscocity = greater resistance to blood flow

28
Q

what does viscocity depend on in blood

A

hematocrit
more rbcs = more viscous, also if dehydrated

29
Q

does blood viscosity vary a lot

A

no since hematocrit varies little
blood viscosity generally constance at time
should be similar in all blood compartments
lenght of bvs also constant in organism

30
Q

describe poiseuilles law

A

frictional losses in viscous flow = generation of heat –> fall in pressure down vessel

R = 8pivL/A^2 = 8pivL/(pir^2)^2 = 8vL/pir^4
resistance = 8 x viscosity x length/radius
valid only for laminar flow

31
Q

what does viscosity depend on

A

viscosity and length of vessel usually constant
cross sectional area = changes, very important

32
Q

what can control resistance in vessels

A

local metabolites (vasoactive peptides)
hormones
neurotransmitters
endothelial cells
increase ca = contract, decrease ca = relax

33
Q

what do endothelial cells do

A

production of endothelium derived relaxing factors = nitric oxide, protascyclin, edhf (endothelium derived hyperpolarizing factor)

34
Q

what helps control resistance

A

contraction

35
Q

what is R relationship

A

R inversely proportional to 1/r^4

36
Q

describe resistance and radius

A

larger = lower resistance
higher vol of blood = must increase pressure and resistance to decrease - arteries

37
Q

describe vessels or organs in series

A

vessels in series
total resistance of 2 vessels in series = to sum of the resistance of vessels 1 and 2
the total resistance is greater than resistance of individual bvs

R=R1+R1

38
Q

describe vessels or organs in parallel

A

resistance at entry and exit of system lower than resistance of each in vessels
radius of vessel at entrance or exit greater than radius of individual vessel
resistance inversely proportional to radius
parallel not efficient

1/R = 1/R1 + 1/R2

39
Q

describe veins and compliance

A

arteries = more resistance and pressure
most of blood found in veins and venules due to high compliance of these bv compared to arteries and arterioles = more resistance

40
Q

what is compliance

A

ability of blood vessel to stretch

41
Q

are veins or arteries more compliant

A

veins
bc little smooth muscle and few elastic layers
more vol, dilate better, relaxes well

42
Q

what does compliance depend on

A

variations or gradient in vessel vol (delta V)
inversely proportional to variation gradient in transmural pressure (delta P)

43
Q

describe compliance in arteries vs veins

A

arteries = for a given variation in transmural pressure = the vol changes little
veins = vol chnages much more for same variation in transmural pressure
venous compliance = more important than arterial compliance

44
Q

what is compliance formula

A

1/slope

45
Q

How is the pressure in the venous system?

A

bp in peripheral veules <10 percent of that in ascending aorta (largest artery)

46
Q

name and describe mechanisms needed to maintain flow of blood in veins against gravity

A

1= valves = system, folds of tunica intima projecting from vessel wall and point in direction of blood flow, ensure one way flow of blood towards heart * can still contract tho, valves ensures proper blood distribution
2 = contraction of skeletal muscles

PHGY 210 (36 decks)

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