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EXCI 259: PHYSIOLOGY > lecture 4: guyton chapter 14 > Flashcards

lecture 4: guyton chapter 14 Flashcards

1
Q

where is conduction in the heart intiated

A

SA node

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2
Q

when there is conduction at the SA node explain the depolar

A

1) signal initted at the SA node (1 cell depolarizes and reaches the rest through synsitium
2) Sign travels to AV node and is slowed down (to allow atrial contraction first)
3) Signal passes through bundle of his (allows signal to pass trhough atria to venticrles
4) purkinje fibers

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3
Q

Why and how is conduction slowed down at AV node

A

it has less gap junctions

slowed to allow atria to contract befroe ventricles (max blood filling)

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4
Q

why does conduction begin at the SA node

A

1) it has a more positive resting membrane potential (can reach threshold faster)
2) has leaky sodium channels (sodium easily flows from the outside to the interior of the cells to reach threshold)

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5
Q

parasympathetic nerves release

A

acetylcholine

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6
Q

which nerve only affects heart rate

A

parasympathetic

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7
Q

parasympathetic nerves release signals where and what does that mean for the heart

A

released only at SA and VA node (on atrial side) which means it only decreases heart rhytm
=SLOWS THE SIGNAL DOWN (signal no longer transmitted to ventricles)

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8
Q

sympathetic nerves release signals where and what does that mean for the heart

A

released through atrial and ventricles which means it affects heart rate and cotnractility
=speeds signal up

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9
Q

what NT do sympathetic nerves release

A

norepinephrin

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10
Q

What are the 2 reasons that HR increases after sympathtetic activation

A

1) cells are more slightly depolazrized (more positive membrane potention=easier to reach membrane potential)
2) stimulates sodium entry into the cell (steeper slope)

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11
Q

what are the 2 reasions that HR decreases adter parasympathtic activation

A

1) cells are slightly hyperpolarized (more negative membrane potential=harder to reach potential)
2) slow is not as steep, less sodium entering in the xell

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12
Q

what are the 5 functions of the cardiovascular system

A

1) Rapid substance transport to and from the tissues and organs of the body.
2) Rapid removal of metabolic waste (carbon dioxide, urea).
3) Distribution of hormones to the tissues/organs of destination.
4) Immune protection.
5) Temperature regulation.

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13
Q

explai nthe fucntion of Temperature regulation in CV system

A

Blood vessels deliver heat from the core to the peripheral areas. Temperature regulation is done by the alteration of the blood flow through the skin. Vasodilation (dilation of arterioles and small arteries) and vasoconstriction (the opposite process) determine temperature locally.

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14
Q

explain the fuction of immune protection of the CV system

A

Specialized blood cells called leucocytes (white blood cells) are used for antibody production.

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15
Q

explain the fucntion of Distribution of hormones to the tissues/organs of destination.
in the CV system

A

Hormones are secretions of the endocrine glands that have specific effects on the functioning of other tissues/organs.
(ex: insulin is made in pancrease but needs to be delivered all over the body)

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16
Q

exaplin the function of Rapid substance transport to and from the tissues and organs of the body.
in the CV system

A

transporting things like Oxygen, glucose, amino-acids, fatty acids, water, vitamins, drugs are carried along blood.

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17
Q

explain the fucntion of Rapid removal of metabolic waste (carbon dioxide, urea).
in the CV system

A

The circulatory system collects the metabolic waste products and delivers them to the excretory organs - e.g., the kidneys, lungs

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18
Q

what are the 5 vessels of the circulatory sytem

A

1) conduction
2) distributing
3) resistance
4) exchange
5) capacitance

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19
Q

true or false: the pump has an electrical system for regular running

A

true

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20
Q

what ppermit rapid exchange between the tissues and the vascular channels

A

extensive system of thin vessels

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21
Q

which is thicker and why: artery or vein

A

artery because it deals with more pressure

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22
Q

what are the special features of the artery

A

muscular, highly elastic

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23
Q

what are the special features of the arteriole

A

muscualr, well innervation

(only 1 monolayer of muscle cells(

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24
Q

what are the special features of capillaries

A

thin walled, highly permeable

only 1 single layer of endothelial cells where excahange happens

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25
Q

what are the special features of venules

A

tin walled, with some smooth msucle

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26
Q

what are the special featurse of veins

A 
thin walled (compared to arteries), fairly muscular, and distensibke 
1 or 2 layers or smoothe muscles
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27
Q

what is the function of the aorta

A

pulse dampening and distrbution

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28
Q

what is the function of large arteries

A

distribution

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29
Q

what is the function of small arteries

A

distrubution and resistance

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30
Q

what is the function of arterioles

A

resistance (pressure/flow reg)

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31
Q

what is the fucntion of capillaries

A

exhchange

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32
Q

what is the function of the venules

A

exchange, collection and capacitance

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33
Q

what is the function of veins

A

capacitance (blood vol)

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34
Q

what is the fucntion of the vena cava

A

collection

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35
Q

Velocity of blood flow is BLANK related to the cross-sectional area of the vascular system

A

inversly

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36
Q

is blood flow velocity slow or fast in capilarries and why

A

very slow

they have a large cross sectional area which makes conditions ideal for exchange of diffusible substances

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37
Q

where is velocity of blood flow greatest

A

in the aorta

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38
Q

rank these from fastest to slowest,

small veins, capillaries, aorta, aterioles

A

aorta
arterioles
small veins
capilaries

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39
Q

what is the equation for velocity of blood

A

blood flow/CSA

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40
Q

what is the defintion of blood flow

A

is the quantity of blood that passes a given point in the circulation in a given period of time.

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41
Q

how is unit of blood flow usally expresed as

A

as milliliters (ml) or Liters (L) per minute.

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42
Q

what is overall flow of an adult

A

is 5 liters/min which is the cardiac output.

43
Q

how does blood usually flow

A

streamlines with each layer of
blood remaining the same distance from the wall, this
type of flow is called laminar flow.

44
Q

what happens when laminar flow occurs

A

the velocity of blood in the center of the vessel is greater than that toward the outer edge creating a parabolic profile.
=vectors in same direction

45
Q

what are the causes of turbulent flow

A

high velocities

sharp turns in the circulation

rough surfaces in the circulation

rapid narrowing of blood vessels

diverstion into smaller streams

46
Q

there is more frction in laminar flow or turbulent

A

turbulent

47
Q

what type of flow is silent and which causes murmurs

A

laminar: silent
turbulent: murmurs

48
Q

why are murmurs important

A

are important in diagnosing vessel stenosis, vessel shunts, and cardiac valvular lesions.

49
Q

what is blood flow to tissues controlled in relation to

A

tissue needs (at rest=equally distrubitioon, during exercise: skeletal gets alot of blood)

50
Q

what is cardiac output mainly controlled by

A

local tissue flow (it is the sum of all local blood flows)

51
Q

true or false: arterial pressure is controlled dependant of local blood flow control or cardiac output control.

A

false

independant

52
Q

what is the difference between blood flow and cardiac output

A

cardiac: amount of blood ejected per min

blood flow: distribution of blood

53
Q

what generates blood flow

A

pumping action of the hert

54
Q

how does pressure arrise

A

when flow is opposed by resistance

55
Q

what is the defintion of BP and the formuala

A

Blood pressure is the force exerted by the blood against any unit area of vessel wall.

BP = CO x TPR

56
Q

where is systemic pressure the highest

A

aorta

57
Q

true or false: systemic pressure decreaess through pathway and reaches 0 mm in right atrium

A

true

58
Q

where does the steepest drop in systemic BP occur

A

in arterioles

59
Q

the arterial blood pressure reflects what two factors of arteries close to the heart

A

Elasticity (compliance or distensibility)

Volume of blood forced into them at any time

60
Q

blood pressure near the heart is called

A

pulsatile

61
Q

where does blood pressure change from pulsatile to continous

A

aterioles

62
Q

def of systolic pressure and normal number

A

pressure exerted in aorta during ventricular contraction

Averages 120 mmHg in healthy adult

63
Q

what is the def of diastolic pressure

A

lowest level of aortic pressure

64
Q

what is pulse pressure

A

difference between systolic and diastolic pressure

Throbbing of arteries (pulse)

65
Q

what is the oressure that propels the blood to the tissues

A

mean arterial pressure

66
Q

true or false: systolic pressure propeles blood to the tissues

A

false, MAP does

67
Q

what is the formula for MAP

A

MAP=diastolic oressure + 1/3 pulse pressure

68
Q

Pulse pressure and MAP both BLANK with increasing distance from heart

A

decline/decrease

69
Q

what is the normal range of capularry blood pressure

A

17-35 mm HG

70
Q

do we want high or low capilarry pressure and why

A

low

Slow capillary flow allows adequate time for exchange between blood and tissues

71
Q

explain low pressure of capillaries and the effect on permeability

A

Most capillaries are very permeable, so low pressure forces filtrate into interstitial spaces

72
Q

true or false: the venous blood pressure changes alot during cardiac cycke

A

false it changes little

73
Q

true or false; there is a small pressure gradient in venous BP (about 15)

A

true

74
Q

why is ther elow pressure in veins

A

Low pressure due to cumulative effects of peripheral resistance

75
Q

where does the energy of BP loss go

A

as heat

76
Q

explain low pressure in venous BP

A

travelling through systemic circulation it loses alot of velocity (slowed down by resistance in arteriole side)

77
Q

what junction do we see a large pressure drop

A

arteriole-capillary junction

78
Q

wht is the defintion of resistance

A

is the impediment to blood flow in a vessel.

Measure of amount of friction blood encounters with vessel walls, generally in peripheral (systemic) circulation

79
Q

how can you calcualte resistance

A

dividing the pressure difference between two points in a vessel by the vessel blood flow

resistance = delta P/flow

80
Q

true or false: its better to have serial resistnce cites in circualtion

A

no its better parallel

81
Q

why is parallel resistnace in circualtion better

A

blood will travel where there is least resistance so if one path is blocked it will move to another
=ALLOWS REDIRECTION OF BLOOD TO WHERE ITS NEEDED

82
Q

what ar ethe 3 imporatnt sources of reisstnace

A

Blood vessel diameter
Total blood vessel length
Blood viscosity

83
Q

what is the greatest influence on resistance

A

blood vessel diameter

84
Q

frequent changes in BLANK alter peripheral resistance

A

in diameter

85
Q

resitance varies inversly with BLANK power of vessel radius

A

with. 4th power

86
Q

example the relationship between vessel radius and resistance

A

increase diamter=increase blood flow= decrease in resistance

ex: if diamter does from 1 to 2 then the flow goes from 1 to 16

87
Q

the resistance is very sensitiv to changes in///

A

radius of a vessel

88
Q

if there is vasocontrictuion, there is an increase or decrase in resistance

A

increase

89
Q

what are the major determinatnts of peripheral resistance

A

small radius arterior

90
Q

abrupt chahgnes in diameter or fatty plaques from atheroscholeros have what affect on ressitance

A

increase
=disrupt laminator flow and causes tubbulent flow
=irregular flow motion=increase sresistance

91
Q

what are the 2 factors that remain constant for resistnace

A

blood viscority and blood vessel length

92
Q

explain blood viscocity effect on resistance

A

The “stickiness” of blood due to formed elements and plasma proteins
Increased viscosity = increased resistance

93
Q

explain blood vessel length effect on ressitance

A

longer vessel =greater resistance

94
Q

do you have higher viscoity in summer or winter

A

summer

95
Q

what is poiseuilles law

A

flow = (pie)(pressure diff)(r)^4/8nl

96
Q

what is conductance and formula

A

is a measure of the blood flow through a vessel for a given pressure difference.
Units ml/min per mmHg

conductance = 1/resistance

97
Q

what is the equation ofr flow

A

flow=change in pressure diff/ressitance

98
Q

what is flow through a blood vessel determined by

A

1) The pressure difference (∆P) between the two ends of the vessel
2) Resistance (R) of the vessel

99
Q

blood flow is BLANK to blood pressure gradient

A 
directly proptional 
(ie: if change in pressure inreases, bloow flow increases)
100
Q

blood flow is BLANK proportional to peripheral resistance

A

inversity

if R increase, blood flow decrease

101
Q

what is more imporant in influencing local blood flow because easily changed by altering blood vessel diameter

A

resistance

102
Q

if arterial pressure and venous pressure remain contant
resistance decreases
what happens to flow

A

increases

103
Q

if arterial and venous pressure stay constant
resistnace icnreases
what happens to flow

A

decreases

EXCI 259: PHYSIOLOGY (21 decks)

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