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259 - physiology > lecture 4: guyton chapter 14 > Flashcards

lecture 4: guyton chapter 14 Flashcards

1
Q

where is conduction in the heart initiated

A

SA node

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2
Q

when there is conduction at the SA node explain the depolar

A

1) signal initiated 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 the bundle of His (allows the signal to pass through atria to ventricles
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 the atrial side) which means it only decreases heart rhythm
=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 the atrial and ventricles which means it affects heart rate and contractility
=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 sympathetic activation

A

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

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11
Q

what are the 2 reasons that HR decreases after parasympathetic 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

explain the function 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) determines temperature locally.

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14
Q

explain the function 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 function of the distribution of hormones to the tissues/organs of the 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

explain 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 function 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 system

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 permits 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

muscular, 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

thin walled, with some smooth muscle

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26
Q

what are the special features of veins

A

thin-walled (compared to arteries), fairly muscular, and distensible
1 or 2 layers or smooth muscles

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27
Q

what is the function of the aorta

A

pulse dampening and distribution

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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

distribution 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 function of capillaries

A

exchange

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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 function 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 capillaries 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
capillaries

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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 definition 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 usually expressed 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 the 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 friction 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 distribution, during exercise: skeletal gets a lot 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 heart

54
Q

how does pressure arise

A

when flow is opposed by resistance

55
Q

what is the definition of BP and the formula

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 decreases 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 continuous

A

arterioles

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 pressure that propels the blood to the tissues

A

mean arterial pressure

66
Q

true or false: systolic pressure propels blood to the tissues

A

false, MAP does

67
Q

what is the formula for MAP

A

MAP=diastolic pressure + 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 capillary 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 a lot during cardiac cycle

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 there low 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

what is the definition of resistance

A

impedes blood flow in a vessel.

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

79
Q

how can you calculate 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 resistance cites in circulation

A

no its better parallel

81
Q

why is parallel resistance in circulation better

A

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

82
Q

what are the 3 important sources of resistance

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

resistance varies inversely with BLANK power of vessel radius

A

with. 4th power

86
Q

example the relationship between vessel radius and resistance

A

increase diameter=increase blood flow= decrease in resistance

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

87
Q

the resistance is very sensitive to changes in///

A

radius of a vessel

88
Q

if there is vasoconstriction, there is an increase or decrease in resistance

A

increase

89
Q

what are the major determinants of peripheral resistance

A

small radius arterior

90
Q

abrupt changes in diameter or fatty plaques from atherosclerosis have what effect on resistance

A

increase
= disrupts laminator flow and causes turbulent flow
=irregular flow motion=increases resistance

91
Q

what are the 2 factors that remain constant for resistance

A

blood viscosity and blood vessel length

92
Q

explain blood viscosity 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 resistance

A

longer vessel =greater resistance

94
Q

do you have higher viscosity in summer or winter

A

summer

95
Q

what is poiseuille’s 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 for flow

A

flow=change in pressure diff/resistance

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 proportional
(ie: if a change in pressure increases, blood flow increases)

100
Q

blood flow is BLANK proportional to peripheral resistance

A

inversly

if R increase, blood flow decrease

101
Q

what is more important 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
resistance increases
what happens to flow

A

decreases

259 - physiology (21 decks)

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