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259 - physiology > lecture 5: chapter 14/15 > Flashcards

lecture 5: chapter 14/15 Flashcards

1
Q

where is blood pressure on the circulatory system the highest

A

in the aorta and largerer arteries

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2
Q

true or false: the pressure stays constant at the aorta

A

true (relatively constant)

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3
Q

Why does the pressure drop significantly at the arteriole/capillary junction

A

They are area of high resistances

Allows velocity to slow for exchange

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4
Q

true or false: the pressure in the systemic circulation stays constant throughout the entire passage

A

false, it decreases until it is at the lowest velocity and pressure near the capillaries

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5
Q

when the blood returns in the right atrium the pressure is 0 mmHH

A

true

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6
Q

where are there lower pressure: arteriol or venous side?

A

venous side

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7
Q

what is peripheral resistance

A

the friction between the blood and vessel wall

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8
Q

what is the main determinant of resistance

A

radius

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9
Q

where is flow faster: larger or smaller vessels

A

faster in large

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10
Q

explain why a smaller radius means a higher resistance

A

because there an increased surface area exposed to blood which will increase resistance (look at slide 3 from 14/15)

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11
Q

what is the relationship between resistance and radius

A

if you increase radius, flow is 16x greater (flow=r4)

Resistance decreases 4 fold (resistance=1/r4)

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12
Q

what are some examples of things that increase resistance

A

abrupt changes in diameter, fatty plaques from atherosclerosis, branching, or sharp turns

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13
Q

what do abrupt changes in direction, fatty plaques etc do in terms of resistance

A

increase resistance and disrupt laminar flow and cause turbulence flow

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14
Q

what is turbulent flow

A

irregular fluid motion that increases resistance

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15
Q

explain why people with heart plaque have hypertension

A

because plaque causes build up in arteries with increases resistance and ie need more pressure to overcome

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16
Q

explain laminar flow

A

during laminar flow all the vectors flow in parallel with the highest velocity and and least friction in the center of the vessels

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17
Q

what are the 3 main determinants of resistance

A

blood viscosity
vessel length
vessel radius

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18
Q

blood is more viscous in what season and gender

A

in men and summer

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19
Q

what is poiseuille’s law

A

flow= (pie)(delta pressure)(radius)^/8nl

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20
Q

what does conductance mean

A

how easy is is to move blood from point a to b

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21
Q

what is the formula for conductance

A

1/resistance

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22
Q

what is the problem with circualtion in series

A

the flow is affected by all resistances

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23
Q

where is an area in the body where blood flows in series

A

in the pulmonary circulation (from heart, to lungs and back to heart)

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24
Q

what is imporant about circulation in parallel

A

it is important for how the body regulates where the blood is going in the body
it allows for separate resistance paths

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25
Q

what is the difference between Q and F

A

Q is the flow through the entire circulation

F is the flow through a certain segmaent

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26
Q

what is the formula for flow

A

q=pressure/resistance

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27
Q

what is the flow through a blood vessel determined by

A

1) the pressure difference between the two ends of the vessel
2) the resistance of the vessel

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28
Q

if pressure increases (and resistance is constant) what happens to the flow

A

it increases

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29
Q

if resistance increases (and pressure is constant) what happens to the flow

A

flow decreases

30
Q

the diastolic pressure is taken at the end of

A

the resting phase when the aortic valve opens

31
Q

after ventricular ejection and pressure is decreases, why does it start to increase again

A

incisura
increase in pressure due to the bouncing off of the peripheral resistance
= important for filling coronary arteries

32
Q

when the left ventricle contracts… more or less blood enters into arterial system

A

more blood enters the arterial system than gets pushed onwards

33
Q

what does the fact that more blood enters the arterial system than gets pushed out when the left ventricle contracts cause what

A

causes arteries to stretch and pressure within them rises

34
Q

the highest pressure in the aorta is called..

A

systolic

35
Q

what happens when the left ventricle relaxes (in terms of recoil)

A

the stretched arterial walls recoil and push the contained blood onward through the system

36
Q

what pushes blood onwards into the circulatory system

A

the elastic recoil of the arteries (compliance)

37
Q

as the arteries recoil what happens to the blood and pressure

A

the amount of blood contained decreases and as does pressure

38
Q

the lowest pressure achieved just before the next contraction is called…

A

diastolic pressure

39
Q

what does arterial compliance mean

A

the ability to expand and recoil

“a change in pressure will affect a change of volume)

40
Q

what is the formula for arterial compliance?

A

compliance=change in volume/change in pressure

41
Q

the walls of which vessel are stronger

A

arteries stronger than veins

42
Q

which vessel has a thicker outer layer but less muscle

A

veins

43
Q

which vessel has thicker walls and how

A

arteries are more rigid because they have more smooth muscle

44
Q

the arteries are less or more distensible than the veins

A

less

45
Q

the arteries are blank times less distensible than the veins

A

8 times less

46
Q

an increase in pressure causes 8 times as much increase in blood in a blank

A

in a vein as in an artery of comparible size

47
Q

if a vein and artery are both subjected to 100 mmHG, how much volume will be in the artery vs vein

A

artery: 100 ml

vein 800 ml

48
Q

what is the reason the veins can hold more blood given the same pressure increase as a artery

A

because of their looser wall (with less smooth muscle), they are more distensible and compliant allowing more blood

49
Q

which vessels are known as the capacitance vessels and why

A

veins since they are the ones that hold the blood

50
Q

what does vascular distensibility mean

A

is the fractional increase in volume for each mmHG rise in pressure

51
Q

veins are more or less distensible than arteries

A

8 times more distensible

52
Q

which arteries are known to be relatively distensible

A

pulmonary

53
Q

what is the formula for vascular distensibility

A

VD= increase in volume/(increase in pressure)(original volume)

54
Q

true or false : vascular distensibility isnt imporant for circualtory function

A

false,it plays an important role

55
Q

what does the distensible nature of the arteries allow

A

allows them to accommodate the pulsatile output of the heart and to average out the pressure pulsations
=provides smooth continuous flow of blood through the very small blood vessels and tissues

56
Q

explain how vascular distensibility allows pulsatile to go to continuous

A

every time a larger vessel expands and recoil it can flatten and dampen the pulsatile flow
-=some of the energy stored in the wall as kinetic becomes potential and the pressure goes forward instead of laterally

57
Q

what is vascular capacitance

A

the total capacitance of blood that can be stored in a given portion of the circulation for each mmHG

58
Q

what is the formula for capacitance

A

distensibility x volume

59
Q

even slight increases in venous pressures cause what

A

cause veins to store 0.5-1 litre of extra blood

60
Q

if there is a slight increase in pressure what does that mean veins can provide

A

provide a reservoir function for storing large quantities of extra blood that can be called into use whenever required elsewhere in circulation

61
Q

true or false: the arteries serve as a reservoir for storing blood

A

false, the veins

62
Q

the capacitance of the veins is smaller or higher than the arteries

A

the capacitance of veins is 24 times that of the arteries

63
Q

any given change in volume within the arterial tree results in…

A

larger increase in pressure than in veins

64
Q

what happens to the blood when veins do vasoconstriction

A

large quantities of blood are transferred to the heart, thereby increasing cardiac output due to an increase in venous return (because of compliance)
=more blood comes in

65
Q

what is the formula for pulse pressure

A

Sys. BP-diastolic BP

66
Q

what are the 2 advantages of distensibility and compliance

A

1) saving energy for the heart

2) pulsatile flow to continuous

67
Q

in the pressure curve, why do we get an elongated tail and why is that beneficial

A

elongated tail because of the compliance (the recoil propel the blood forward so it saves work for the heart)

68
Q

what is the “ohms law” for circulation

A

q=delta p/r

69
Q

CO is the …

A

flow

70
Q

what are the two sources of the pressure

A

mean arterial pressure and central venous pressure

71
Q

what is the source of resistance in the body

A

systemic vascular resistance

72
Q

KNOW THE LAST TWO SLIDES

A

259 - physiology (21 decks)

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