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259 - physiology > lecture 6: guyton chapter 15 > Flashcards

lecture 6: guyton chapter 15 Flashcards

1
Q

what is the definition of compliance (in terms of formula)

A

a change in volume has an an influence of change in pressure

ability to expand and recold

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2
Q

true or false: in arteries and veins, the same increase in pressure will cause a small increase in volume

A

false, because veins are more compliant and distensible, the same pressure increase will have a different change in volume

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3
Q

which is more compliant arteries or veins

A

veins

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4
Q

what is the definition of vascular distensibility

A

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

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5
Q

how much more distensible are veins than arteries

A

8x

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6
Q

what is the eq. For vascular distensibility

A

=increase in volume/increase in pressure x origin volume

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7
Q

what makes arteries less compliant than veins

A

they are harder and thicker because of a larger layer of smooth muscles

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8
Q

what makes veins more compliant than arteries

A

they are thinner and less rigid (less smooth muscle cells) so they can expand easier

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9
Q

veins are more more distensible and therefore have a lower o r higher compliance

A

higher

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10
Q

what is the definition of vascular capacitance?

A

is the total quantity of blood that can be stored in a given portion of the circulation for each mmHg.

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11
Q

which vessel has a larger capacitance veins or arteries and why

A

since veins have a higher distensibility and therefore more compliant they can store a lot more blood in the venous side

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12
Q

how much percentage of blood is held on venous side

A

60-70 percent

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13
Q

what is the formula of capacitance

A

distensability x volume

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14
Q

small and large veins are called what type of vessels

A

capacitance vessels

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15
Q

changes in vasculature are induced by what

A

compliance

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16
Q

explain the arterial system in terms of hydraulic filter

A

Composed of elastic conduits (aorta and arteries) and high-resistance terminals (arterioles)

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17
Q

what is the function of the hydraulic filtering in the arterial system

A

converts intermittent output of the heart to a study flow in capillaries

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18
Q

what happens to part of the energy of cardiac contraction

A

is dissipated as forward capillary flow during systole (kinetic energy)

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19
Q

what is the remainder of the energy of the cardiac contraction stored as (that is not kinetic )

A

potential

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20
Q

why is the remainder of energy of cardiac contraction stored as potential energy

A

because of compliance

=much of the stroke volume is retained by stretching the distensible arteries

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21
Q

During diastole the elastic recoil of the arterial walls converts this potential energy what

A

into capillary blood flow

=continuous

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22
Q

what is the perk of the hydraulic filtering

A

This minimizes the workload of the heart, i.e., more work is required to pump a given flow intermittently as compared to steadily

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23
Q

what effect allows the conversion of intermittent blood flow to continuous

A

windkessel effect or elastic reservoir

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24
Q

true or false: The pressure curves change in arteries at different distances from the heart

A

true

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25
Q

what are the 3 major changes in the pressure curve

A

The high-frequency components of the pulse, such as the incisura, are damped out and soon disappear

The systolic portions of the pressure wave become narrowed and elevated

A hump may appear on the diastolic portion of the pressure wave

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26
Q

what happens to the high frequency components (such as insura) when increasing distance from the heart

A

gets dampened out and soon disappear

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27
Q

ass we get further from the hear what happens to the systolic portions of the pressure wave

A

because narrowed and elevated

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28
Q

what may appear on the diastolic portion of the pressure wave

A

a hump

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29
Q

what happens to the intensity of pulsations are we get to the small arteries

A

become progressively less intense

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30
Q

if no compliance what would happen to an elongated tail

A

it would disappear and heart would have to work harder

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31
Q

the degree of dampening is proportional to what

A

proportional to the resistance of small vessels and arterioles and the compliance of the larger vessels.

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32
Q

there is more dampening in smaller or larger vessels

A

smaller

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33
Q

why is the dampening importance

A

because it allows to go from pulsatile to continuous

34
Q

what would happen if the vessels were rigid

A

ALL the blood the heart pumped would be immediately converted to flow

During diastole, there would be no flow (including no flow to capillaries)

35
Q

pumping blood through rigid vessels creates what

A

more work for heart

36
Q

elastic arteries ensure what

A

constant flow through capillaries and

reduce work of heart through the pumping

37
Q

true or false: age has no effect on arterial compliance

A

false it has a large effect

38
Q

why does BP increase as age increases

A

due to more stiffness in vessels which means the heart needs to work harder to combat more resistance

39
Q

why is it bad if the arteries are rigid

A

they do not expand and recoil

40
Q

as we get older our arteries get STIFFER/LOOSER and therefore more/less compliant

A

stiffer

Less

41
Q

what is the main reason the arteries get stiffer with age

A

loss of elastic tissue

ellastin is all made by age 10 so after that it starts to degrade

42
Q

what are 2 factors affecting pulse pressure

A

stroke volume

arterial compliance

43
Q

explain the relationship between stroke volume and pulse pressure

A

increases in
stroke volume increase pulse
pressure conversely decreases
in stroke volume decrease
pulse pressure.

44
Q

explain the relationship between arterial compliance and pulse pressure

A

decreases in compliance increases pulse pressure; increases in compliance decrease pulse pressure.

45
Q

increased aortic pulse pressure is affected by what 2 main things

A

decreased aortic compliance

increased stroke volume

46
Q

what are reason for decreased aortic compliance

A

age
arteriosclerosis
hypertension

47
Q

what are the 4 factors that increase stroke volume

A

increase preload
decreased afterload
increased inotropy/contractility
decreased HR

48
Q

what are 3 abnormal pressure pulse controls

A

arteriosclerosis
patent ductus arteriosus
aortic regurgitance

49
Q

explain arteriosclerosis

A

decreases the compliance of arterial tree, thus leading to an increase in pulse
=build up of plaque in vessel and narrows which impedes flow and increases BP

50
Q

explain patent ductus arteriosus

A

associated with low diastolic pressure and high systolic pressure, net result is very high pulse pressure.

=small hole means that mixing aortic and pulmonary blood

51
Q

explain aortic regurtitation

A

a condition associated with the backward flow of blood through the aortic valve. Low diastolic and high systolic pressure leads to high pulse pressure.

=valve does not close completely, leaking blood into the heart

52
Q

know the graph of pulse controls

A

jng

53
Q

what causes resistance to flow in large peripheral veins

A

compressional factors

54
Q

what do increases in right atrial pressure cause

A

causes blood to back up into the venous system, thereby increasing venous pressures.

55
Q

where is the highest venous pressure

A

in the legs and feet

56
Q

what tends to increase venous pressures in the legs

A

abdominal pressure

57
Q

what is central venous pressure

A

pressure in larger veins close to the heart

58
Q

what determines the filling pressure of right ventricle

A

CVP

59
Q

explain how CVP determines filling pressure of the right ventricle

A

an increased CVP increase blood flow which assists in filling and increase diastolic volume

60
Q

what are the 2 things that regulate CVP

A

A balance of the heart to pump blood out of the right atrium and right ventricle into the lungs

The tendency for blood to flow from the peripheral veins to the right atrium (venous return)

61
Q

what are the 6 factors that increase CVP

A

Decreased Cardiac Output

Increase in Total Blood Volume

Venous Constriction

Gravity
Standing to supine position

Respiratory Activity
Increased depth and rate of respiration

Skeletal Muscle Pump
Exercise

62
Q

explain how increase in total blood volume increases CVP

A

more blood in system=more blood to the venous side which means the heart needs more pressure to move it

63
Q

explain how venous constriction increases CVP

A

the venous constricts which affects pressure

64
Q

explain how gravity increases CVP

A

standing=more pressure
supine=lower pressure

with less pressure the venous return is not working against gravity which means it will increase venous return, increase stroke volume and decrease cardiac output

65
Q

explain how respiratory activity increases CVP

A

when increase breathing rate and depth you increase the suction of blood back to the heart since it is situated above the diaphragm

66
Q

explain how skeletal muscle pump/exercise increases CVP

A

when the skeletal muscles are working the contact on and off (pumping) which milks the veins
helps blood move back towards the heart

67
Q

gravitational pressure effects pressure how

A

Pressure rises 1 mmHg for each 13.6 mm distance below the surface of a body of water

68
Q

give an example to show the pressure difference due to gravity

A

feet: 90 mmHG
sagital sinus
= -10 mmHG

69
Q

what can you get if you decrease pressures further from heart

A

you can increase venous return

70
Q

what are the 3 types of respiration that effect CVP

A

spontaneous respiration (normal)

mechanical ventilation

valsava manoeuvre

71
Q

explain the effect of spontaneous respiration

A

Decreased intra-thoracic pressure results in a decreased right atrial pressure which enhances venous return

= Lowering diaphram creates a negative pressure in the thoracic cavity which facilitates the filling of lungs and larger veins with blood from the lower body

72
Q

explain the effect of mechanical respiration

A

Increased intra-thoracic pressure during positive-pressure lung inflation causes increased right atrial pressure which decreases venous return

=breathing towards positive pressure which means right atrial pressure increases since it will have a hard time pushing blood down into ventricles

high pressure in the in lungs causes alveoli will be inflated and push on capillaries and creating high resistance
= Blood will be retained in the right ventricle, right atrium won’t push blood down
=must increase venous pressure to overcome the resistance

73
Q

explain the affect of valsave method on respiration

A

Causes a large increase in intra-thoracic pressure which impedes venous return to the right atrium  lower CO

= Exhaling against closed glottis, increase pressure in the thoracic cavity so blood cannot travel easily
=no blood passing so the heart will not contract and no cardiac output = no BP

74
Q

contracted skeletal muscle does what for the veins

A

increases venous pump

to push blood towards heart

75
Q

what is the function of valves

A

prevent backflow

76
Q

explain what contraction of muscles do

A

contract of muscles pushes blood up which will push open the valves

77
Q

if there is an increase in right atrial pressure what is the effect on flow

A

flow will be decreased which means CVP must increase to compensate

78
Q

60-70% of blood is stored where

A

in veins

79
Q

under various physiological conditions what can happen to the blood

A

it can be transferred to the arterial system to maintain arterial pressure
=vasoconstriction

80
Q

what are some examples of reservoirs

A

spleen, liver, large abdominal veins and venous plexus

81
Q

what serves as a good special reservoir for red blood cells

A

spleen

82
Q

what are some examples of non venous blood reservoirs

A

heart

lungs

259 - physiology (21 decks)

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