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Physiology > Cardiovascular Physiology III (EXAM III) > Flashcards

Cardiovascular Physiology III (EXAM III) Flashcards

1
Q

Blood flow through the smallest vessels in the circulatory system (arterioles, venules, capillaries)

A

Microcirculation

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2
Q

List whether the vessel description is characteristic of a vein or artery:

  1. Few layers of smooth muscle & connective tissue
  2. Many layers of smooth muscle & connective tissue
A
  1. Vein
  2. Artery
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3
Q

List whether the vessel description is characteristic of a vein or artery:

  1. Several elastic layers
  2. Few elastic layers
A
  1. Artery
  2. Vein
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4
Q

List whether the vessel description is characteristic of a vein or artery:

  1. Small lumen
  2. Wide lumen
A
  1. Artery
  2. Vein
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5
Q

If you compare an arteriole to a venule, an arterior still has more:

A

Smooth muscle

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6
Q

Simple squamous epithelial layer with smooth muscle on the outside:

A

Arteriole

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7
Q

Simple squamous endothelial layer with nothing on the outside:

A

Capillary

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8
Q

Simple squamous layer with some connective tissue on the outside:

A

Venule

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9
Q

The tissue that lines all vessels:

A

Endothelial tissue (Simple squamous epithelial layer)

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10
Q

Why is the lumen of a vein more open compared to an artery:

A

Because veins lack tone

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11
Q

What is the name for the largest arteries? List examples:

A

Elastic arteries
- aorta & pulmonary trunk

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12
Q

What is the name for the middle sized arteries? List examples:

A

Muscular/Distribution arteries
- arteries that branch off aorta and branch within the organs

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13
Q

What is the name of the smallest arteries?

A

Arterioles

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14
Q

At each level, arteries compared to veins have (3):

A
  1. Thicker walls
  2. More elastic tissue
  3. More smooth muscle
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15
Q

Level of vascular smooth muscle contraction:

A

Vascular tone

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16
Q

What determines the radius of the vessel lumen?

A

Vascular tone

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17
Q

____ in tone would lead to an an increase in vasoconstriction and a decrease in lumen diameter

A

Increase in tone

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18
Q

____ in tone would lead to an increase in vasodilation and an increase in lumen diameter

A

Decrease in tone

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19
Q

How does an increase in tone effect resistance?

A

Increases resistance

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20
Q

How does a decrease in tone effect resistance?

A

Decreases resistance

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21
Q

A change in vascular tone leads to a change in _____ and a changes in ______

A

Resistance & a change in blood flow through the vessel

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22
Q

What is the equation for blood flow through a vessel?

A

Q= (change in pressure) / (resistance)

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23
Q

What is the equation showing the relationship between resistance with length of the vessel & radius:

A

R= (8Ln)/(pi)(radius^4)

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24
Q

Tone can be modified by (2):

A
  1. Paracrines from endothelial cells
  2. Autonomic nervous system
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25
Q

Gives three examples of paracrines from endothelial cells & explain their effects:

A
  1. Nitric Oxide (NO) - decreases tone & relaxes smooth muscle
  2. Prostayclin- decreases tone & relaxes smooth muscle
  3. Endothelin-1 - increases tone & relaxes smooth muscle
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26
Q

Describe what scenarios the parasympathetic nervous would effect vascular tone:

A

Parasympathetic innervation mediates vasodilation only in the arteries supplying the penis & clitoris (therefore decreasing vascular tone)

This is the only situation in which the parasympathetic nervous system would have influence on vascular tone (never would it increase vascular tone)

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27
Q

Describe the sympathetic NS influence on vascular tone of smooth muscle:

A

Depends on neurotransmitter but most often will increase vascular tone

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28
Q

When an artery/arteriole is somewhat contracted in its resting state:

A

Basal tone

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29
Q

Basal tone is mediated by (2):

A
  1. Paracrine secreted by endothelial cells
  2. Tonic activity of sympathetic motor neurons
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30
Q

If ______ sympathetic activity to arteries and arterioles that would function to increase tone

If you ____ sympathetic activity to arteries & arterioles that would function to decrease tone

A

Increase; decrease

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31
Q

What allows arteries/arterioles to vasodilate & vasoconstrict from rest?

A

Due to their basal tone

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32
Q

Describe the basal tone in veins in venules:

A

Not present, they are fully relaxed in resting state

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33
Q

Due to veins/venules not exhibiting basal tone, they can only ____ from rest:

How do they do this?

A

Vasoconstrict

Mediated sympathetic nervous system

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34
Q

(High) Abnormal arterial tone=

A

Idiopathic hypertension (most common cause of HTN_

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35
Q

How easily a structure stretches:

A

Compliance

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36
Q

Equation for compliance:

A

Compliance = (change in volume) / (change in pressure)

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37
Q

Describe the compliance of vessels that can have large changes in volume with little changes in pressure:

Give an example

A

High compliance

Veins

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38
Q

Why do we describe veins as having high compliance:

A

Due to the ability to have large changes in volume with little changes in pressure

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39
Q

Describe compliance of vessel that can have large changes in pressure with little changes in volume:

Give an example

A

Low compliance

Arteries

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40
Q

Why do we describe arteries as having low compliance?

A

Due to the ability to have large changes in pressure with little changes in volume

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41
Q

Anytime we vasoconstrict the veins we:

We ____ venous return
We ____ EDV
We _____ SV
We _____ co

A

Increase all of these

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42
Q

What is the driving for blood flow in the circulatory system?

A

Pressure gradient

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43
Q

Pressure in the arterial vessels is ______ producing ____ & ____ pressures:

A

Pulsatile
Systolic & Diastolic

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44
Q

What happens to pulsation once it reaches the capillaries:

A

It smoothes out

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45
Q

Why does pulsation “smooth out” once we hit the capillaries?

A
  1. Due to decreasing elastic/collagen tissue
  2. Increasing resistance as you move through arteries to capillaries
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46
Q

What is the maximum of the pulsatile pattern of pressure?

What is the minimum of the pulsatile pattern of pressure?

A

Systole

Diastolic

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47
Q

The smoothing out of flow (no more pulsations) related resistance of blood flow & compliance of the vessel:

A

Dampening

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48
Q

What vessels have the greatest resistance to blood flow?

Because of this what do we see once blood reaches this location?

A

Arterioles

Greatest drop of pressure due to greatest amount of dampening

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49
Q

The degree of dampening in a vessel is directly related to:

A

Resistance of blood flow & compliance of a vessel

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50
Q

Corresponds to the peak pressure in the left ventricle during ventricular systole:

A

Systolic

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51
Q

Corresponds to the minimum pressure in the artery that is the pressure that the left ventricle has to overcome to open semilunar valves:

A

Diastolic

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52
Q

What is the driving force to get the blood to the capillaries (numerical value)

A

63 mmHg

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53
Q

Describe the location of the highest pressure vessels

A

Closest to left ventricle

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54
Q

Arteries can be described as ____ compliance, ____ elastance vessels

A

Low; High

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55
Q

Represents the elastic recoil of the aorta:

A

Dicrotic notch

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56
Q

The elastic recoil of the aorta is caused by:

A

The walls of the aorta snapping back from stretched position back into place

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57
Q

The elastic recoil of the aorta is essential to:

A

Assure the diastolic pressure does not fall too low

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58
Q

Elastic recoil maintains the:

A

Driving pressure (diastolic pressure)

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59
Q

Average driving pressure in systemic arteries:

A

MAP

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60
Q

Equation for mean arterial pressure:

A

MAP= Diastolic + 1/3 (Systolic - Diastolic)

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61
Q

What is the mean arterial pressure for a BP of 120/80?

A

93 mmHg

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62
Q

Which pressure (systolic or diastolic) has the greatest influence on MAP? Why?

A

Diastolic- because the ventricle spends a lot more time in diastole than it does in systole

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63
Q

What is the standard normal driving pressure in systemic circulation?

A

93 mmHg

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64
Q

What happens to MAP with arteriosclerosis?

A

Arteriosclerosis is stiffening of the arteries so elastic recoil (snapping back of aorta) is compromised so these individuals have issues with venous return (getting blood back to the heart)

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65
Q

Mechanistic explanation of arteriosclerosis:

A

Because recoil of aorta is blunted, you wouldn’t get as much of a “dicrotic notch” & the pressure would drop more than it normally would

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66
Q

How would heart function change to compensate in individuals with arteriosclerosis:

A

The heart would have to beat more forcefully if you want to have good perfusion through systemic circulation

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67
Q

Felt as the pulsation or throb in the arteries of the wrist or neck with each heartbeat:

A

Pulse pressure (PP)

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68
Q

Equation for pulse pressure:

A

PP= (SP-DP)

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69
Q

What would PP of BP 120/80 equal:

A

PP=(120-80)

= 40 mmHg

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70
Q

What are the most important factors in determining the magnitude of pulse pressure?

A
  1. Stroke Volume
  2. Arterial Compliance
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71
Q

Describe the relationship of pulse pressure to:

  1. Stroke Volume
  2. Arterial compliance
A
  1. Directly related to
  2. Inversely related to
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72
Q

Anything that decreases compliance will _____ pulse pressure

Anything that increases compliance will _____ pulse pressure

A

Increase

Decrease

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73
Q

In an individual with ateriosclerosis to maintain driving pressure their heart must contract more forcefully during systole. How will this affect MAP?

A

It will increase MAP

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74
Q

Diseased state characterized by the failure of the aortic valve to completely & fully open:

A

Aortic stenosis

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75
Q

Arteriosclerosis results in a reduced ______ while aortic stenosis results in a reduced ______

A

Compliance; SV

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76
Q

Why does aortic stenosis results in a reduced stroke volume?

A

You have to force blood out of the aorta through a narrow opening & this leads to a reduced stroke volume because you cannot efficiently pump blood out

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77
Q

We can SELECTIVELY vary the amount of blood flow to different tissues & organs by:

A

Adjusting the radius of the vessels

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78
Q

If we want to selectively increase blood flow to the liver but decrease blood flow to the kidneys how might this be accomplished?

A

Dilate vessels leading to liver

Constrict vessels leading to kidney

(overall selectively changing the radius of the vessel)

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79
Q

We can selectively increase or reduce blood flow to a tissue due to the blood vessels being:

A

In parallel

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80
Q

Average driving pressure in systemic circulation to move blood through the blood vessels:

A

MAP

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81
Q

Increased MAP results in what diseased state?

A

HTN

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82
Q

HTN is caused by an increase in systolic and/or diastolic pressure. HTN 70 million Americans:

(T/F)

A

Both statements are true

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83
Q

HTN affects 1/5

(T/F)

A

F- 1 in 3

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84
Q

Describe what happens to the blood pressure when an individual starts to age:

A

Systolic starts to rise & diastolic starts to fall

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85
Q

A rise in systolic & fall in diastolic pressure as an individual starts to age represents:

A

Arterial stenosis

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86
Q

Normal blood pressure is considered:

A

Systolic less than 120
Diastolic less than 80

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87
Q

Elevated blood pressure is considered:

A

Systolic: 120-129
Diastolic: less than 80

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88
Q

Stage 1 HTN:

A

Systolic: 130-139
Diastolic: 80-89

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89
Q

Stage 2 HTN:

A

Systolic: 140+
Diastolic: 90+

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90
Q

Hypertensive crisis:

A

Systolic: 180+
Diastolic: 120+

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91
Q

What are the three factors that influence MAP?

A
  1. Flow in & out of systemic arteries
  2. Total blood volume
  3. Distribution of blood in circulatory system
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92
Q

The flow IN to systemic arteries:

The flow OUT of systemic arteries:

A

CO

TPR

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93
Q

Vasoconstriction of arteries would function to increase:

A

Total peripheral resistance (TPR)

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94
Q

The sum of all the resistance of all systemic arterioles in the body:

A

Total peripheral resistance (TPR)

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95
Q

If:

Flow in > Flow out (due to increased CO or increased TPR) would have what affect on MAP?

A

Increase (due to accumulating volume)

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96
Q

If:

Flow in < Flow out (due to decreased CO or decreased TPR) would have what affect on MAP?

A

Decrease (due to volume depletion)

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97
Q

Equation involving CO & TPR:

A

MAP = CO x TPR

98
Q

How would an increase in total blood volume affect MAP?

What is an example of something that might cause this?

A

Increase in MAP

Increased sodium intake (salty meal)

99
Q

How would a decrease in total blood volume affect MAP?

What is an example of something that might cause this?

A

Decrease in MAP

Hemorrhage (bleeding out)

100
Q

How can distribution of blood in circulatory system affect MAP?

A

Blood can be shifted from veins to arteries to increase MAP

101
Q

When blood is shifted to veins (from arteries) we _____ MAP

When blood is shifted to arteries (from veins) we ____ MAP

A

Increase; Decrease

102
Q

Normally ____% of blood volume is in arteries & ____% of blood volume is in veins`

A

11% Arteries
60% Veins

103
Q

TPR is directly related to:

A

The sum of resistance in the arterioles

104
Q

Factors that change arteriolar diameter change the ____ of arterioles which ultimately changes _____

A

Resistance of arterioles
TPR

105
Q

Arteriolar diameter is influenced by what three things?

A
  1. Autoregulation
  2. Local Control
  3. Systemic/Reflex control
106
Q

Regulation of TPR:

Autoregulation is a function of:

A

Blood vessel wall

107
Q

Assures blood flow to tissue matches tissue demands:

A

Autoregulation (of arteriolar diameter)

108
Q

Regulation of TPR:

Local control is a function of:

A

Paracrines

109
Q

Matches tissue blood flow to metabolic demands:

A

Local control (of arteriolar diameter)

110
Q

According to local control of arteriolar diameter regulation

Flow to tissue=

A

MAP/ Resistance of the tissue

111
Q

In a tissue that is more metabolically active, if we want to increase blood flow:

We want reduce _______
We do NOT want to increase ______

A

Resistance

MAP

112
Q

Arteriolar diameter regulator that functions to maintain MAP to assure adequate blood flow to the brain & heart:

A

Systemic/reflex control

113
Q

What will be altered in systemic/reflex control of arteriolar diameter to keep map constant?

A

CO & TPR

114
Q

Systemic/ Reflex control is a function of:

A

NS & ES

115
Q

According to systemic/reflex control of arteriolar diameter:

MAP=

A

CO x TPR

116
Q

Controls the flow into capillaries:

A

The resistance of arterioles

117
Q

A function of arterioles that is a regulatory reflex that assures that blood flow into tissues does go up just because BP is increased:

A

Myogenic autoregulation

118
Q

Reflex arteriolar constriction is a response to:

A

Increased MAP

119
Q

Nearly all organs tend to keep their blood flow constants despite variations in:

A

Arterial pressure

120
Q

When is the only time we would want to increase blood flow to an organ?

When would we NOT want to increase blood flow to an organ?

A

If the organ is more metabolically active; if BP goes up

121
Q

What is the myogenic autoregulation range & what does this mean?

A

80-180 mmHg

This means that changes in MAP in the range of 80-180 will not result in an increase in tissue blood flow to that tissue

122
Q

T/F: An increase in MAP leads to an increase in tissue blood flow

A

False

123
Q

T/F: AN increase in MAP above 180 mmHg will lead to an increase in tissue blood flow; explain

A

True (out of myogenic autoregulation range)

124
Q

The normal mean arterial pressure is 93 mmHg, describe where this sits in the myogenic autoregulation range:

A

Sits pretty far away from the high end & much closer to the lower end

125
Q

Factors regulation arteriolar systemic resistance:

A
  1. Myogenic autoregulation
  2. Paracrines
  3. Reflex control
126
Q

Interstitial concentration of paracrine substances changes as cells become:

A

More or less metabolically active

127
Q

Increased tissue metabolism results in:

Decreased O2
Increased CO2
Increased H+
Increased K+

All of this will lead to ____ of the arterioles

A

Vasodilation

128
Q

Decreased tissue metabolism results in:

Increased O2
Decreased CO2

This will lead to ____ of the arterioles:

A

Vasoconstriction

129
Q

Increased tissue metabolism leads to ____ blood flow to that tissue

Decreased tissue metabolism leads to ___ blood flow to that tissue

A

Increased

Decreased

130
Q

Process in which an increase in tissue blood flow accompanies an increase in metabolic activity:

A

Active hyperemia

131
Q

Once metabolic activity in the tissue goes up we see an increase in organ blood flow to match the metabolic demands, this is referred to as:

A

Active hyperemia

132
Q

We DO NOT want blood flow to increase due to:

We DO want blood flow to increase due to:

A

Increasing BP

Increasing metabolic needs

133
Q

Increased tissue blood flow following a period of low perfusion:

A

Reactive Hyperemia

134
Q

If blood flow to a tissue space is occluded, _____ will accumulate in the interstitial space:

Give examples:

A

Paracrines

Decreased O2
Increased CO2
Increased H+

135
Q

Hypoxia stimulates endothelial cells to secrete _____ which is a potent _____ that will accumulate in interstitial space:

A

NO
Vasodilator

136
Q

Once occlusion is removed, paracrines cause ____ and increase in ______ until paracrines are washed away and arteriolar diameter returns to _____

A

Vasodilation
Tissue blood flow
Resting state

137
Q

The ________ mechanisms are how flow to to a tissue is matched to its metabolic activity

A

Local control mechanisms

138
Q

What accumulate in the ECF during reactive hyperemia:

A

Metabolic vasodilators

139
Q

Once the occlusion is removed in reactive hyperemia what happens to resistanvec & blood flow:

A

Resistance decreases
Blood flow increases

140
Q

In reactive hyperemia, as the vasodilators are washed away by blood flow, arterioles _____ and blood flow _____

A

Constrict; returns to normal

141
Q

List the vasodilating paracrines (leading to an increase in tissue blood flow) (8):

A
  1. CO2
  2. H+ (lactic acid)
  3. Adenosine (from ATP usage)
  4. K+ (due to AP)
  5. Prostaglandins
  6. Bradykinins
  7. Nitric oxides (NO)
  8. Low O2
142
Q

List the vasoconstricting paracrines (leading to a decrease in tissue blood flow) (3):

A
  1. O2 (tissue isn’t doing a whole lot if it is not utilizing O2_
  2. Endothelin
  3. Thromboxanes
143
Q

Factors regulating arteriolar resistance:

Maintains MAP as constant as possible to have adequate blood flow to brain & heart:

A

Reflex control

144
Q

In situations, if necessary reflex control can overide:

A

Local control

145
Q

Reflex control is a function of:

A

Nervous system & endocrine systems (getting big dogs & whole body involved)

146
Q

Sympathetic postganglionic neurons to skeletal muscle arterioles release ______ which binds to ______

A

Norepinephrine

Alpa-1 receptors

147
Q

When the sympathetic postganglionic neurons release NE that binds to the Alpha-1 receptors, this results in:

A

Vasoconstriction

148
Q

The adrenal medulla secretes ____ into blood which can bind to _____ & cause _____ or can bind to _____ & cause _____ in the smooth muscle in skeletal muscle arterioles

A

Epinephrine

Alpha-1 receptors —> Vasoconstriction
Beta-2 receptors –> Vasodilation

149
Q

The sympathetic post-ganglionc neurons to skeletal muscle arterioles release the norepinephrine to cause an increase in NE in the ______

The adrenal medulla secretes epinephrine into the blood to cause an increase in epi in the _____

A

ECF

Plasma

150
Q

Describe the location of Beta-1 receptors in tissues:

A

Only found in very specific tissue spaces-
Coronary vessels, skeletal muscle arterioles, superficial skin vessels

151
Q

Overall we have more vasoconstriction than vasodilation so ______ will go up when the SNS is activated:

A

TPR

152
Q

Other hormones that act as vasoconstrictors include:

A

Anti-diuretic hormone (ADH)
Angiotensin II (ANGII)

153
Q

Other hormones that act as vasodilators include:

A

Atrial natruretic peptide (ANP)

154
Q

The hormone ANP functions to:

A

Reduce blood volume & blood pressure:

155
Q

Not only does ANP act on the kidney to promote ______, it acts on vascular smooth muscle to increase ______ and ultimately decrease _______.

A

Decreased blood volume; Vasodilation, decrease MAP

156
Q

Lots of hormones are designed to maintain blood volume & blood pressure but only ______ is designed to BRING IT DOWN

A

ANP

157
Q

The reflex control regulating arteriolar resistance uses ____ & _____ controls

A

Neural & hormonal

158
Q

What equation can be used to describe REFLEX CONTROL:

A

MAP = CO x TPR

159
Q

What equation can be used to describe local control?

A

Qtissue= MAP / Resistance of arterioles

160
Q

Beta-1 receptors in the heart are activated by norepinephrine & epinephrine & function to:

A

Increase HR & Stroke volume

161
Q

Increase in blood pressure has what effect on resistance?

A

Increases resistance

162
Q

Anything that increases venous return will also increase, SV, CO, MAP, EDV

A

Starling’s law of the heart

163
Q

Intrinsic generation of heart rate can be modulated by:

A

Sympathetic & parasympathetic motor neurons

164
Q

Stroke volume can be modulated by:

A

+ inotropic agents

165
Q

Veins have _____ distinct layers (tunics)

A

Three

166
Q

The walls of veins are _____ compared to arteries so they often appear collapsed in histological slides

A

Thinner

167
Q

Compared to arteries veins have (3):

A
  1. Less smooth muscle
  2. Less elastic tissue
  3. Higher compliance
168
Q

Veins are highly distensible so they are called ______ that act as _____

A

Capacitance vessels; Blood reservoirs

169
Q

Pressure gradient available for venous return is around _____

This is not sufficient to ____

A

15 mmHg; To move blood back to heart

170
Q

Mechanisms supporting venous return include (4):

A
  1. Venous valves
  2. Respiratory pump
  3. Skeletal muscle pump
  4. Venoconstriction
171
Q

Explain how the respiratory pump functions in supporting venous return:

A

Every time we breath in we lower thoracic pressure, this creates greater pressure gradient which functions to increase venous return

(the faster you breath in, the faster you return blood back to heart)

172
Q

Explain how the skeletal muscle pump functions in supporting venous return:

A

Contracting skeletal muscle squeezes on vein which move blood towards heart (one-way valves function here)

173
Q

Explain how venoconstriction functions in supporting venous return:

A

Sympathetic NS & adrenal medulla release NE & E (respectively) which binds to alpha-1 adrenergic receptors and this causes venoconstriction, which reduces compliances & increases pressure & ultimately promote venous return

174
Q

When one-way valves do not function:

(could be due to dilation of veins or leaky veins, however causes blood accumulation in the veins)

A

Varicose veins

175
Q

About _____ % of adults suffer from varicose veins and it is most prominent in the _____

A

15%; lower limbs

176
Q

What are the four determinants to increase peripheral venous pressure?

A
  1. Increase activity of sympathetic nerves to veins
  2. Increase blood volume
  3. Increase skeletal muscle pump
  4. Increase inspiration movements
177
Q

An increase in venous pressure has what effect on venous return?

A

Increased venous return

178
Q

An increase in venous return has what effect on atrial pressure?

A

Increased atrial pressure

179
Q

An increase in atrial pressure has what effect on end diastolic ventricular volume (EDV)?

A

Increased end diastolic ventricular volume

180
Q

An increase in EDV has what effect on stroke volume?

A

Increased stroke volume

181
Q

Valsalvas maneuver has what effect on VR?

A

Decreases venous return

182
Q

Mechanistic explanation to why blood flow is slowest in the capillaries:

A

Due to greatest total cross-sectional area

183
Q

Teleological explanation to why blood flow is slowest in the capillaries:

A

We want blood flow to take time here so maximum exchange can occur

184
Q

Blood flow velocity is fastest in the ____ & slowest in the _____

A

Fastest in the arteries
Slowest in the capillaries

185
Q

Blood volume is highest in the _____ & lowest in the _____

A

Venules/Veins
Arterioles

186
Q

Diastolic & systolic blood pressure is highest in the _____ & lowest in the _____

A

Arteries
Venules/Veins

187
Q

Vascular resistance is highest in the ______ & lowest in the ______

A

Arterioles
Venules/Veins

188
Q

What is the amount of driving force pressure to get the blood through the capillaries (numerical value)

A

20 mmHg

189
Q

Capillaries are big enough to let ______ RBC(s) through at a time

A

One

190
Q

Describe the anatomy of a capillary

A
  1. Single layer of endothelial cells (capillary wall)
  2. Basement membrane
  3. Single nucleus
191
Q

Because capillaries are NOT connected via ______ they contain ___ that serve as a mechanism for capillary exchange

A

Tight junctions; narrow water-filled spaces

192
Q

Movement of fluid & dissolved substances via bulk flow occurs ______ in capillaries & serves as a mechanism of capillary exchange

A

Down a pressure gradient

193
Q

In capillaries vesicles may fuse to form _____ which connects the _____ to the _____

A

Water-filled channel
Lumen of capillary to interstitial fluid

194
Q

What process can occur in the water-filled channels of capillaries?

A

Bulk flow down a pressure gradient

195
Q

______ & ______ transport are two mechanisms of capillary exchange that will either use vesicles or passive and active processes in the cell membrane

A

Transcytosis & Transepithelial transport

196
Q

Simple diffusion in capillaries is a mechanism of capillary exchange to transport ________ substances

A

Hydrophobic

197
Q

What is the difference between plasma & interstitial fluid?

A

Plasma contains more protein than interstitial fluid because the protein is too big to fit through capillary spaces

198
Q

What is NOT small enough to fit through the capillary spaces?

A

Blood cells & large plasma proteins

199
Q

As blood move through the capillary bed ____ is dumped off & ____ is picked up

A

O2
CO2

200
Q

Part of the capillary made of intermittent smooth muscle & is the MOST DIRECT ROUTE between arterioles & venules
(some exchange does occur here)

A

Metarteriole/Thoroughfare Channel

201
Q

Branch off ateriole & metarteriole and take alternate paths to go from arteriole to venule side:

A

Capillaries

202
Q

Describe pre-capillary sphincters:

A

Made of smooth muscle & function to control the entrance to capillaries

203
Q

Not a capillary, rather a direct connection between arteriole & vein in which exchange DOES NOT occur:

A

Ateriovenous anastomosis

204
Q

If i am talking about a more direct route without exchange I am referring to ______

This path allows for things like ____ & ____ to go from ateriole to venule side

A

Ateriovenous anastamosis

WBCs & large proteins

205
Q

Amount of blood & pathway the blood travels through a capillary bed varies moment to moment based on:

A

Tissues metabolic activity

206
Q

Metarteriole & pre-capillary sphincters fluctuate between:

A

Contracted & relaxed state

207
Q

The rate of fluctuation of contraction/relaxation in metarteriole & pre-capillary sphincters is primarily controlled by:

A

O2 in the tissue

208
Q

When the concentration of O2 in the tissues is low, smooth muscle spends more time in a _____ state & the blood takes a ____ path through the capillary bed

A

Relaxed; convoluted

209
Q

When the concentration of O2 in tissues is high, smooth muscle spends more time in a ____ state & blood takes a more ____ path through the capillary bed

A

Contracted; direct

210
Q

In times of high metabolic activity in tissues what do the paracrines function to do (2):

A
  1. Paracrines function to dilate the arteriole in the process of active hyperemia
  2. Paracrines function to relax pre-capillary sphincters
211
Q

In really metabolically active tissue describe the pre-capillary sphincters:

A

Stays open longer & closes less resulting in more of the capillary bed to be perfused with blood flow

212
Q

In a not very metabolically active tissue describe the pre-capillary sphincters:

A

Lack of paracrines causes pre-capillary sphincters to close off, therefore less perfusion occurs

213
Q

In the case that the tissue is not metabolically active and pre-capillary sphincters are closed off, how might the blood travel to the venous side?

A

Direct route is the only option in this case

(ateriovenous anastamosis)

214
Q

What is the driving force to get blood through the capillaries?

A

20 mmHg

215
Q

The capillaries are made of a _____ layer of _____ cells (makes up the capillary wall)

A

Single layer of endothelial cells

216
Q

Mechanism of capillary exchange that is due to the capillaries not being connected via tight junctions:

A

narrow water filled spaces

217
Q

In a capillary what travels through the narrow water filled spaces?

A

Fluid & dissolved substances

218
Q

The movement of fluid & dissolved substances in capillary exchange occurs via:

A

Bulk flow

219
Q

The mechanism of capillary exchange (bulk flow) occurs:

A

Down a pressure gradient

220
Q

Mechanism of capillary exchange in which vesicles fuse to form water filled channels connects:

A

Lumen of capillary to interstitial fluid

221
Q

When vesicles fuse to form water filled channels that connects the lumen of the capillary to the interstitial fluid, the movement of substances through this channel occurs via:

A

Bulk flow (down a pressure gradient)

222
Q

Mechanism of capillary exchange in which vesicles are used to move substances across the cell or passive & active processes in the cell membrane:

A

Transcytosis & Transepithelial transport

223
Q

A mechanism of capillary exchange used for hydrophobic substances:

A

Simple diffusion

224
Q

What is not small enough to fit through the capillary channels through the capillary wall spaces?

A

Blood cells & large plasma proteins

225
Q

What is the difference between plasma & interstitial fluid?

A

Plasma has more proteins than interstitial fluid

226
Q

As blood moves through the capillary bed ____ is dumped off & _____ is picked up:

A

O2
CO2

227
Q

Most direct route between arteriole & venule; intermittent smooth muscle; some exchange does occur here:

A

Metarteriole/Thoroughfare channel

228
Q

Branch off arteriole & metarteriole:

A

Capillaries

229
Q

Capillaries take ____ paths to go from arteriole side to venule side:

A

Alternative paths

230
Q

Control entrance to capillaries:

A

Pre-capillary sphincters

231
Q

Pre-capillary sphincters are made of:

A

smooth muscle

232
Q

Direct connection between arteriole & vein

A

Ateriovenous anastamosis

233
Q

Describe the exchange that occurs in the ateriovenous anastamosis:

A

No exchange occurs

234
Q

Arteriovenous anastomosis are NOT capillaries & allow things like ____ to go from the arteriole side to the venule side via a direct path WITHOUT exchange

A

WBCs & large proteins

235
Q

The amount of blood & pathway the blood travels through the capillary bed varies ______ based on the tissue’s ______

A

Moment to moment; metabolic activity

236
Q

Metarteriole and pre-capillary sphincters fluctuate between:

A

Contracted & relaxed state

237
Q

The rate of fluctuation between contracted & relaxed states of the metarteriole and pre-capillary sphincters is controlled primarily by the:

A

Concentration of oxygen in the tissue

238
Q

When the concentration of oxygen is low in the capillary network, smooth muscle spends more time in the _____ state & blood takes the ____ path through the capillary bed

A

Relaxed; convoluted

239
Q

When the concentration of oxygen is high in the capillary network, smooth muscle spends more tine in the ____ state & blood takes the ___ path through the capillary bed

A

Contracted; Direct

240
Q

When tissue becomes more metabolically active oxygen is decreased and H+, CO2 & paracrines become _____

The paracrines will function to _____ the arteriole through the process of ____

What affects do the paracrines have on pre-capillary sphincters?

A

Increased
Vasodilate; active hyperemia
They relax the precapillary sphincters

241
Q

Velocity is the _____ in capillary beds

Why?

A

Slowest; because they have the greatest cross-sectional area

242
Q

The path the blood travels through the capillary is dependent on the:

A

Metabolic state (active or nonactive) of the tissue

Physiology (11 decks)

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