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Physiology > Vascular Phys > Flashcards

Vascular Phys Flashcards

0
Q

Circulatory nutrient delivery

A

rapid delivery to within 10-20 micrometers of most cells

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1
Q

Circulatory Functions

A
  1. Nutrient & waste exchange
  2. Electrolyte & H2O balance
  3. Body temp regulation
  4. Delivery of hormones
  5. Delivery of defense mechanisms
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2
Q

Microcirculation consists of

A

arterioles, capillaries, venules

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3
Q

Microcirculation location

A

within organs

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4
Q

arterioles =

A

stopcock of organ blood flow

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5
Q

Veins are

A

reservoir of blood in the body

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6
Q

What happens when veins constrict?

A

there is an increase in venous return

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7
Q

% Total Blood Volume in Pulmonic Circulation

A

9%

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8
Q

% Total Blood Volume in Systemic Circulation

A

84%

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9
Q

% Total Blood Volume in Heart

A

7%

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10
Q

Cardiac Output Redistributed for Changes in Metabolic Demands based on..

A

reconditioning and non-reconditioning organs

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11
Q

Reconditioning Organs

A

have role in “reconditioning” blood to improve it for entire body
ex: GI tract, Kidneys,

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12
Q

amount of blood received by reconditioning organs

A

more blood than necessary for metabolic needs

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13
Q

Reconditioning organs can..

A

tolerate reduction in blood flow when need be because they get more than needed

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14
Q

Non-reconditioning Organs

A

ONLY receive exact amount of blood they need to live

ex: brain, heart, skeletal muscle, bone

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15
Q

Hemodynamics

A

study of physical factors that determine blood flow & blood pressure in the body

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16
Q

Physical Factors of Hemodynamics

A

pressure, velocity, flow, resistance, diameter, velocity

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17
Q

Systemic Pressure

A

high pressure

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18
Q

pulsatile blood pressure

A

increase and decrease of artery blood pressure (125/80)

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19
Q

pulsatile blood pressure in arteries

A

occurs because of cardiac systole

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20
Q

pulsatile blood pressure in capillary beds is based on:

A
  1. Distensibility of large arteries

2. Frictional resistance of small arteries & arterioles

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21
Q

Why is pulsatile blood pressure in capillaries important?

A

It provides constant movement & supply of blood in organs & allows for constant exchange.

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22
Q

Pulmonic pressure

A

low pressure

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23
Q

Why is pulmonic pressure low pressure?

A

less resistance to overcome (shorter tube length)

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24
Q

Why do you want a low pressure in pulmonic circulation?

A

high pressure would drive fluid out of capillary beds & into the lung tissue

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25
Q

PVR (Pulmonary Vascular Resistance)

A

sum of resistance of vasculature in pulmonary circulation

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26
Q

SVR (Systemic Vascular Resistance)

A

sum of resistance of vasculature in systemic circulation

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27
Q

PVR compared to SVR

A

PVR ««< SVR

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28
Q

Velocity of blood

A

varies inversely as a function of cross-sectional area (CSA)

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29
Q

What happens if CSA increases?

A

Velocity decreases & get maximal exchange in capillaries

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30
Q

What happens if CSA decreases?

A

velocity increases and amount exchanged decreases

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31
Q

Vena Cava velocity vs. aorta velocity

A

vena cava’s velocity is lower than aorta because it’s a bit larger than the aorta

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32
Q

Flow through all levels of circulation

A

constant

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33
Q

Flow velocity varies

A

as a function of CSA of each level

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34
Q

Flow Velocity =

A

particle movement (distance) per unit time

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35
Q

Flow rate

A

rate of displacement of volume of a fluid

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36
Q

Flow depends on

A

pressure gradient and vascular resistance

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37
Q

Pressure gradient is the…

A

primary force of blood flow

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38
Q

Flow is

A

independent of absolute/individual pressure levels

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39
Q

Resistance depends on

A

vessel radius, vessel length, and blood viscosity

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40
Q

Vessel Radius

A

changes in the body as necessary

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41
Q

blood viscosity

A

friction of molecules in blood stream

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42
Q

What changes to influence resistance?

A

vessel radius

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43
Q

What doesn’t change to affect resistance?

A

vessel length and blood viscosity

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44
Q

What happens if you increase vessel radius 2X?

A

you decrease resistance 16X & increase flow 16X

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45
Q

Viscosity

A

varies as a function of hematocrit

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46
Q

normal hematocrit

A

40% total blood volume

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47
Q

normal blood viscosity vs water viscosity

A

3x greater than water’s

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48
Q

If blood viscosity is 3X higher than water’s,

A

resistance is higher & pressure must increase 3X to push blood through vasculature

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49
Q

Types of Changes in Viscosity

A
  1. Anemia

2. Polycythemia

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50
Q

Anemia

A

low RBC count

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51
Q

anemia effects on circulation

A

decreases viscosity, decreases resistance, decreases pressure, increases venous return, increases cardiac output, causes hypoxia (decreased O2 delivery), which increases CO more,

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52
Q

What happens if you’re anemic and CO can’t keep up with metabolic needs?

A

heart failure… death!

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53
Q

Polycythemia

A

high RBC count

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54
Q

Polycythemia’s effect on blood

A

increases viscosity, increases resistance, increases pressure, decreases flow, decreases venous return, increases blood volume

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55
Q

increased blood volume in polycythemia

A

offsets the decrease in venous return caused by polycythemia which maintains normal CO

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56
Q

Vessel Arrangements

A
  1. Parallel

2. Serial

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57
Q

Parallel Vessel Arrangements

A

occurs in most systemic vascular beds

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58
Q

Parallel Vessel Arrangement affect on Resistance

A

Total R < R of individual component in parallel arrangement

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59
Q

benefits of parallel vessel arrangements

A
  1. Reduces SVR
  2. Blood flow is independently adjusted
  3. Blood flows at similar perfusion pressure
  4. Arterial blood is of identical composition
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60
Q

Significance of arterial blood being of identical composition in parallel vessel arrangements

A

organs see “fresh” blood. not blood that’s passed through other organs first

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61
Q

Serial Vessel Arrangement occurs in

A

splanchnic & renal beds

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62
Q

Serial Vessel Arrangement’s affect on resistance

A

high resistance

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63
Q

Serial Vessel Arrangement’s affect on pressure

A

drop in pressure gradient as you move across each bed

64
Q

Patterns of Blood Flow

A
  1. Laminar

2. Turbulent

65
Q

Laminar Blood Flow

A
  • normal
  • streamlined & straight
  • silent
66
Q

Turbulent Blood Flow

A
  • mostly abnormal

- noisy

67
Q

Turbulent blood flow used diagnostically for

A
  • murmurs

- bruits

68
Q

murmurs

A

cardiac valvular lesions

69
Q

bruits

A

vessel stenosis, shunts

70
Q

critical velocity

A

where flow switches from laminar to turbulent

71
Q

Reynolds Number

A

measure of tendency for turbulence to occur

72
Q

Example of Bruit

A 
arteriovenous fistula (joining of artery & vein)
decrease in BP => increased CO to accomodate
73
Q

Turbulence is created by…

A
  1. Large vessel diameter (aorta)
  2. Large Vessel branch points
  3. High velocity (anemia)
  4. Obstruction (atherosclerosis)
  5. Low viscosity (anemia)
74
Q

Turbulence frequencies

A

high in aorta

low in small vessels

75
Q

Role of Arteries in Vascular System

A

to convert intermittent output of heart to steady flow into capillaries

76
Q

Arteries are..

A
  • elastic
  • distribution channels
  • pressure reservoirs
  • contain little resistance to flow
77
Q

Arterioles are…

A

muscular

78
Q

Arterioles function

A

control blood flow through capillaries

79
Q

arterioles’ resistance

A

high.

have greatest amount of R in system to control blood flow

80
Q

Compliant Arteries

A
  • in young, healthy animals

- very elastic arteries

81
Q

Compliant Arteries allow

A

arteries to behave as pressure reservoirs (aka can swell)

82
Q

Rigid Arteries are…

A
  • in older animals

- have lost some elasticity

83
Q

Rigid arteries produce

A

high afterlaod

84
Q

Effect of rigid arteries’ loss of elasticity

A

loss of function as pressure reservoir in circulatory system

85
Q

Flow in Rigid Arteries

A

stops in diastole

occurs only in systole

86
Q

Flow in Compliant Arteries

A

continues during systole & diastole

87
Q

Effect of discontinuous flow in rigid arteries

A

intermittent flow occurs in capillary beds, so exchange isn’t continuous

88
Q

Pulse Pressure =

A

systolic BP - diastolic BP = SV/arterial compliance

89
Q

Pulse pressure function

A

sharp upstroke in P (systole) -> P starts decreasing ->aortic valve shuts -> slight increase in P -> exponential decline in P (diastole) -> REPEAT

90
Q

Abnormal pulse pressures

A

can be used diagnostically

91
Q

Arteriosclerosis Pulse Pressures

A

high systolic P. Normal diastolic P. normal dichrotic notch

92
Q

Aortic Stenosis Pulse Pressures

A

low, flat systolic P
normal diastolic P
no/small dichrotic notch

93
Q

Patent Ductus Arteriosus Pulse Pressures

A
  • High systolic P
  • Low diastolic P
  • Normal dichrotic notch
94
Q

Aortic Regurgitation Pulse Pressures

A
  • High Systolic P
  • Low Diastolic P
  • No dichrotic notch
95
Q

Primary job of heart

A

control MAP

96
Q

Barrow reflex starts when

A

MAP decreases

97
Q

Effect of Barrow Reflex Starting

A

Increases CO, Increased systolic P

thereby maintaining normal BP

98
Q

Arterioles Job

A

control blood flow in capillaries

99
Q

Arterioles provide ___ resistance

A

greatest resistance to control flow

100
Q

Arterioles control of resistance

A

independently control resistance by smooth muscle contraction

101
Q

Why is independent control of R important for arterioles?

A

It permits arterioles to have precise control of flow into individual capillary beds & aids in BP regulation

102
Q

Result of constricting arterioles

A

increase MAP upstream

decrease MAP downstream

103
Q

Result of dilating arterioles

A

Decrease MAP upstream

Increase MAP downstream

104
Q

basal tone

A

allows dilation under basal conditions & maintains BP

105
Q

How does basal tone work?

A
  1. Myogenic stretch

2. Basal Norep. release

106
Q

Myogenic stretch

A

stretch Ca channels open & increase cytosolic [Ca]

107
Q

Opening of stretch Ca channels occurs

A

when P is put on walls, & the walls stretch

108
Q

Why does more cytosolic [Ca] increase basal tone?

A

Ca is essential for smooth muscle contraction

109
Q

Basal norep. release occurs

A

at sympathetic nerve fibers

110
Q

Basal norep. binds

A

to adrenergic receptors & leads to vessel contraction/constriction

111
Q

Independent Arteriolar Control caused by

A

systemic and local factors

112
Q

Extrinsic Control/Systemic Responses done by:

A
  1. Neural influence (sympathetic N.S.)

2. Humoral Factors

113
Q

Job of Extrinsic Control/Systemic Responses

A

regulate blood pressure

114
Q

Intrinsic Control/Local Control done by:

A
  1. Metabolic Factors
  2. Endothelium-mediated
  3. Myogenic Responses
  4. Shear stress
115
Q

Job of Intrinsic Control/Local Control

A

determine cardiac output distribution

aka determines which organs get which blood

116
Q

Intrinsic Control/Local Control regulates:

A
  1. Autoregulation

2. Reactive Hyperemia

117
Q

Metabolic Factors are important in

A

brain, heart, skeletal muscle

118
Q

Intrinsic Control vs Extrinsic Control

A

Intrinsic OVERRIDES extrinsic

119
Q

Constriction of Arterioles caused by

A

sympathetic nerves stimulate smooth muscle contraction

120
Q

How does sympathetic innervation cause smooth m. contraction?

A
  1. Releases norep. into neuromuscular junction
  2. Norep. binds to a-1 adrenergic receptors
  3. Ca released & contraction occurs
121
Q

What happens if you increase sympathetic nerve activity?

A

Increase norep. release => VASOCONSTRICTION => increased R => decreased flow

122
Q

What happens if sympathetic nerve activity decreases?

A

decreases norep. release => VASODILATION => decreased R => increased flow

123
Q

Exception to sympathetic nerve stimulation of smooth m. contraction

A

brain

124
Q

Why is the brain the exception to smooth m. contraction by sympathetic nervous stimulation?

A

Brain has no a-1 receptors.

125
Q

How do the brain’s arterioles contract?

A

use local mechanisms to maintain constant blood flow

126
Q

Parasympathetic N.S. & Arterioles

A

basically has no effect

dilates arterioles in salivary glands, GI glands, & genetalia

127
Q

Humoral Factors

A
  • Norep. for a-1 receptors in most arteriolar smooth m.

- Ep. for b-2 receptors

128
Q

Epinephrine for B-2 receptors Function

A

stimulates arterioles of heart & skeletal m. to dilate

129
Q

Epinephrine =

A

“breaks” for cardiovascular system

130
Q

How does epinephrine work?

A

It works with other local mechanisms to counteract a-1 constriction

131
Q

Angiotensin II

A

potent vasoconstrictor

132
Q

Vasopressin

A

potent vasoconstrictor

133
Q

Angiotensin II & Vasopressin function

A

maintain amount of salt that kidneys retain by being released into blood stream

134
Q

Metabolites cause…

A

local vasodilation

135
Q

Active hyperemia

A

increased blood flow to highly active tissues

136
Q

Reactive Hyperemia

A

increased flow to tissue AFTER flow is acutely blocked

137
Q

How does reactive hyperemia work?

A

occlusion occurs & increases metabolite build up. When occlusion is released, flow increases to remove metabolites => longer removal time based on occlusion time

138
Q

exercise effect

A

combination of occlusion & exercise increases [metabolite] => higher increase in flow

139
Q

Local Vasoactive Mediators come from

A

endothelium

140
Q

Types of local vasoactive mediators

A
  1. Vasodilators

2. Vasoconstrictors

141
Q

Vasodilators

A

NO, prostacylin, EDHF

142
Q

Vasoconstrictors

A

endothelin, Angiotensin II, prostaglandins

143
Q

Sheer Stress

A

longitudinal frictional resistance between blood & vessel walls

144
Q

Myogenic Mechanism

A

a smooth muscle phenomenon

145
Q

Example of Sheer Stress mechanism

A

aids in increasing flow in tissues w/ increased metabolic demand by dilating vessels.
small arterioles dilate to metabolites well => increased sheer stress in small upstream aa. => NO release => dilation of small aa.

146
Q

How myogenic contraction works?

A

changes in transmural pressure alters contractile states of arterioles

147
Q

Myogenic Mechanism resulting from ^ pressure

A

^P => opening of stretch activated Ca channels => ^ Ca influx => ^ contraction => decreased r => decreased flow

148
Q

Autoregulation of Flow

A

maintains normal organ flow despite changes in arterial pressure

149
Q

What organs autoregulate best?

A

brain, heart, kidneys

150
Q

Autoregulation of Flow Mediated by:

A

myogenic and metabolic responses

151
Q

If perfusion pressure decreases,

A

flow decreases & therefore need to decrease R to ^ flow to normal levels

152
Q

When perfusion pressure decreases what causes a decrease in R to bring flow back to normal?

A

sympathetic discharge

153
Q

Sympathetic discharge effects

A

no change in pressure. arterioles dilate. Resistance decreases.

154
Q

Myogenic response to decreased perfusion pressure

A

decreased stretch, less Ca entry, increased relaxation (DILATION)

155
Q

Metabolic response to decreased perfusion pressure

A

increased [metabolite] => increased dilation to get more out

156
Q

Increased perfusion pressure effects

A

increased flow meaning R needs to increase to bring flow back DOWN to normal levels

157
Q

Myogenic response to increased perfusion pressure

A

^ stretch, ^ Ca entry, ^ contsriction, ^ R, decreased flow

158
Q

Metabolic response to increased perfusion pressure

A

decreased [metabolite], ^ constriction to keep metabolites at normal levels in the region

Physiology (10 decks)

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