Exam #4 Flashcards

1
Q

3 types of cells the ANS controls

A

smooth muscle cells
cardiac muscle cells
gland cells

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2
Q

where do SNS preganglionic fibers originate

A

thoracolumbar region of the spinal cord (T1-L2/3)

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3
Q

where do SNS preganglionic cell bodies lie in the spinal cord

A

intermediolateral horn

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4
Q

where do SNS preganglionic cell fibers pass through in the spinal cord

A

ventral root

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5
Q

where do SNS preganglionic fibers travel once they leave the spinal canal

A

pass through white ramus, into one of the ganglia of the sympathetic chain

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6
Q

what can SNS preganglionic neurons do once they are inside the sympathetic chain

A

synapse with post ganglionic neuron in the ganglion (travel through gray rami to periphery)

Go up or down the sympathetic chain to synapse at another level

exit the chain to an outlying collateral ganglion where they can synapse with a peripheral synpathetic ganglion

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7
Q

where do post ganglionic sympathetic neurons originate

A

one of the sympathetic chain ganglia

one of the peripheral sympathetic ganglia

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8
Q

5 peripheral sympathetic ganglia

A

celiac
superior mesenteric
aorticorenal
inferior mesenteric
hypogastric

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9
Q

what is released at the terminal end of the SNS preganglionic neuron

A

ACh

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10
Q

SNS preganglionic fiber length

A

short

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11
Q

SNS post ganglionic fiber length

A

long

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12
Q

what is released at the terminal end of the post ganglionic neuron at synapses with target organ

A

NE

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13
Q

chromaffin cells

A

ACh interacts with them to release EPI and NE in the adrenal medulla

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14
Q

catecholamine content released by chromaffin cells

A

80% EPI
20% NE

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15
Q

how long do hormonal EPI and NE last vs direct stimulation

A

10x longer

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16
Q

what is the result of SNS stimulation of the liver

A

glycogenolysis– glucose released into the blood

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17
Q

synthesis of NE

A

tyrosine+ tyrosine hydroxylase->
DOPA+ decarboxylase->
dopamine+ DBH->
transported into vesicles and converted to NE

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18
Q

3 mechanisms by which NE is removed after the release into the synapse

A

reuptake into the presynaptic terminals (active transport)

diffusion away from nerve endings

destruction by tissue enzymes (MAO and COMT)

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19
Q

What does the metabolism of NE form

A

VMA

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20
Q

what is VMA

A

the major metabolite (80-90%) of NE found in urine

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21
Q

are SNS preganglionic fibers myelinated or unmyelinated

A

myelinated

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22
Q

preganglionic fiber to postganglionic fiber ratio in SNS

A

1:20-30

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23
Q

NE negative feedback loop

A

NE binds in the presynaptic post ganglionic sympathetic nerve terminal to a2 receptors and NE release is decreased

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23
Q

where does PSNS arise from

A

CN3,7,9,10
sacral segments 1-4
The craniosacral outflow

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24
Q

PSNS preganglionic nerve terminals release _____ which binds to what receptor

A

ACh
nicotinic

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25
Q

PSNS post ganglionic nerve terminals release ____ which binds to what receptor

A

ACh
muscarinic

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26
Q

define nerve

A

bundle of axons

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27
Q

define dendrite

A

receive incoming signals
the strength of the signal dictates whether the nerve will pass the signal on which is an action potential

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28
Q

at rest, there are more ____ charged ions outside the cell

A

positively

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29
Q

the inside of the cell has a net ____ charge at rest

A

negative

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30
Q

what is the membrane potential threshold voltage

A

-55

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31
Q

what is the membrane potential resting voltage

A

-70

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32
Q

what are myelin sheaths made of in PNS

A

schwann cells

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33
Q

gaps in schwann cells are called and what is their impact

A

nodes of ranvier
jumping from node to node speeds the transmission

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34
Q

what are myelin sheaths made of in the SNS

A

oligodendrocytes

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35
Q

ACh synthesis

A

Acetyl-CoA +choline via the enzyme choline acetyltransferase

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36
Q

where is ACh synthesized and stored

A

synaptic vesicles in axon terminal

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37
Q

how is ACh hydrolyzed

A

acetylcholinesterase to choline and acetate
choline is reused

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38
Q

SNS solely provides innervation to the (3)

A

blood vessels
spleen
piloerector muscles

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39
Q

define cholinergic

A

nerves that operate by using ACh

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40
Q

define adrenergic

A

nerves that operate using NE

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41
Q

define muscarinic

A

drugs that mimic the effects of muscarine which activates the PNS (heart, smooth muscle, glands)

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42
Q

define nicotinic

A

drugs that interact with ganglionic and skeletal muscle synapses and on nerve membranes and sensory endings

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43
Q

where to preganglionic neurons originate

A

brainstem or spinal cord

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44
Q

where are nicotinic receptors located

A

on preganglionic fibers in the PNS, SNS, NMJ, and adrenal medulla

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45
Q

what activates nicotinic receptors

A

ACh and nicotine

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46
Q

ACh binds to the alpha subunit on the receptor-> conformational change-> increased conductance for ___ which leads to a strong inward electrical and chemical gradient for ___ which leads to what

A

Na+
Na+
depolarization of the postsynaptic cell

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47
Q

where are muscarinic receptors located

A

post ganglionic fibers in the PNS on the heart, smooth muscle, and exocrine glands

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48
Q

how do muscarinic receptors affect the heart

A

inhibitory
(blocked by atropine)

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49
Q

how do muscarinic receptors affect the smooth muscle and glands

A

excitatory

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50
Q

what activates muscarinic receptors

A

ACh
muscarine

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51
Q

CNIII

A

oculomotor

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52
Q

CNVII

A

facial

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53
Q

CNIX

A

glossopharyngeal

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54
Q

CNX

A

vagus

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55
Q

which nerve transmits 75% of the PNS

A

vagus

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56
Q

vagus nerve supplies what(6)

A

heart
tracheobronchial tree
liver
spleen
kidney
entire GI tract (except distal colon)

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57
Q

length of preganglionic fibers in the PSNS

A

long

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58
Q

length of the postganglionic fibers in the PSNS

A

short

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59
Q

preganglionic to postganglionic ratio in the PSNS

A

1:1-3

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60
Q

all post ganglionic parasympathetic neurons are

A

cholinergic

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61
Q

all preganglionic parasympathetic neurons are

A

cholinergic

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62
Q

all preganglionic sympathetic neurons are

A

cholinergic

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63
Q

postganglionic sympathetic neurons that innervate the sweat glands and blood vessels are

A

cholinergic

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64
Q

preganglionic sympathetic neurons that arise from the greater splanchnic nerve and innervate the adrenal medulla are

A

cholinergic

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65
Q

all motor nerves that innervate skeletal muscle are

A

cholinergic

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66
Q

where are alpha1 receptors located

A

postsynaptic membrane of sympathetic postganglionic neurons

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67
Q

where are alpha1receptors found (8)

A

peripheral vasculature
renal vascular smooth muscle
coronary arteries
myocardium
skin
uterus
intestinal mucosa
splanchnic beds

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68
Q

alpha1 receptors mediate what

A

smooth muscle vasoconstriction

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69
Q

post synaptic alpha 2 responds primarily to what

A

epi

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70
Q

6 actions of alpha 2 receptors

A

arterial and venous constriction
platelet aggregation
inhibition of insulin release
inhibition of bowel motility
stimulation of growth hormone release
inhibition of ADH release

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71
Q

4 central actions of alpha 2 receptors

A

sedation
anxiolysis
analgesia
hypnosis

72
Q

where are beta 1 receptors located

A

post synaptic membrane

73
Q

3 locations of beta 1 receptors

A

cardiac tissue
kidneys
adipose tissue

74
Q

what neurotransmitter are beta 1 receptors primarily responsive to

A

NE

75
Q

3 actions of beta 1 receptors on cardiac tissue

A

increase HR, conduction velocity, and contractility

76
Q

where are beta 2 receptors found

A

both presynaptic and post synaptic membranes

77
Q

where are beta 2 receptors lcated

A

smooth muscle of blood vessels in
skin
muscle
mesentery
bronchi
cardiac tissue

78
Q

effects of beta 2 activation on smooth muscle

A

vasodilation, bronchial smooth muscle relaxation, and renal vessel relaxation

79
Q

cardiac effects of beta 2 activation

A

increase in HR and contractility

80
Q

what is the result of presynaptic beta 2 activation

A

opposes the presynaptic alpha 2
accelerates NE release

81
Q

what neurotransmitter do beta 2 receptors primarily respond to

A

Epi

82
Q

effects of NE on inotropism in the normal heart is mediated by what receptor(s)

A

beta 1 receptors

83
Q

inotropic effects of epi are mediated through what receptor(s)

A

beta 1 and 2 receptors

84
Q

alpha receptor effect on vessels

A

vasoconstriction

85
Q

alpha receptor effect on eyes

A

iris dilation

86
Q

alpha receptor effect on intestines

A

relaxation

87
Q

alpha receptor effect on intestinal sphincter

A

contraction

88
Q

alpha receptor effect on skin

A

pilomotor contraction

89
Q

alpha receptor effect on bladder

A

sphincter contraction

90
Q

beta receptor effect on vessels

A

vasodilation

91
Q

beta receptor effect on heart

A

cardioacceleration
increased myocardial strength

92
Q

beta receptor effect on intestines

A

relaxation

93
Q

beta receptor effect on uterus

A

relaxation

94
Q

beta receptor effect on lungs

A

bronchodilation

95
Q

beta receptor effect on bladder

A

wall relaxation

96
Q

beta receptor effect on metabolism (4)

A

thermogenesis
calorigenesis
glycogenolysis
lipolysis

97
Q

term for measurable, gas filled spaces in the lung

A

lung volume

98
Q

term for combination of two or more lung volumes

A

lung capacity

99
Q

define expiratory reserve volume

A

volume of gas that can be maximally exhaled from the end-expiratory level

100
Q

normal expiratory reserve volume

A

1L or 2x Vt

101
Q

define inspiratory reserve volume

A

volume of gas that can be maximally inhaled from the end-inspiratory level

102
Q

normal inspiratory reserve volume

A

2L or 6x Vt

103
Q

define residual volume

A

volume of gas remaining in that lung after maximal exhalation

104
Q

fick’s law

A

rate of diffusion through sheet of tissue is proportional to:
issue area
difference in gas partial pressures b/w the 2 sides and
solubility

inversely proportional to:
tissue thickness
molecular wt

105
Q

CO2 vs O2 diffusion

A

CO2 diffuses 20x faster than O2 d/t increased solubility and equal molecular weight

106
Q

define functional residual capacity

A

volume of gas present in the lung at end expiration during tidal breathing
FRC= ERV+RV

107
Q

normal functional residual capacity

A

2-2.5L

108
Q

define inspiratory capacity

A

max vol. of gas that can be inspired
IC=IRV+VT

109
Q

define vital capacity

A

the volume change between max inspiration and expiration
VC= IRV+VT+ERV

110
Q

define total lung capacity

A

sum of all volume compartments
TLC=IRV+VT+ERV+RV

111
Q

define alveolar ventilation

A

the amount of fresh gas that gets to alveoli

112
Q

define dead space ventilation

A

portion of ventilation that does not participate in gas exchange

113
Q

define minute ventilation

A

volume exhaled with each breath * RR/min= minute ventilation

114
Q

define anatomic dead space

A

the volume of the conducting airways

115
Q

how much is anatomic dead space

A

150mL

116
Q

define alveolar dead space

A

volume of the alveoli where normal gas exchange takes place, but due to disease or trauma, is not able to do so

117
Q

define physiologic dead space

A

the total volume of the lung that does not eliminate CO2

118
Q

normal alveolar ventilation

A

4.2L/min

500mL inhaled - 150mL anatomic dead space= 350 in gas exchange *12RR= 4.2L

119
Q

which alveoli are better ventilated

A

dependent areas

120
Q

pleural pressure and compliance of upper zone

A

less pleural pressure, distended more, less compliant

121
Q

pleural pressure and compliance of lower zone

A

more pleural pressure, less distended, more compliant

122
Q

fick’s law equation

A

R= (D A ∆p)/d

R= rate of diffusion
D=diffusion constant
A= area over which diffusion occurs
∆p= difference in pressure between the two sides
d= distance over which diffusion occurs

123
Q

3 characteristics of pulmonary vasculature

A

low pressure
highly elastic
vessel walls thin

124
Q

how much of the circulating blood volume is in the pulmonary circulaiton

A

10%

125
Q

normal mPAP

A

15

126
Q

normal PAP

A

25/8

127
Q

normal pulmonary capillary pressure

A

8-10

128
Q

normal LA pressure

A

5

129
Q

normal LV pressure

A

120/0

130
Q

normal systemic capillary pressure

A

30
20
10

131
Q

4 determining factors of pulmonary circulation pressure

A

cardiac output
pulmonary arterial pressure
pulmonary vascular resistance
left atrial pressure (pulmonary venous pressure)

132
Q

what happens when alveolar pressure>capillary pressure

A

alveoli collapse

133
Q

define transmural pressure

A

pressure difference between the inside and outside of the capillaries

134
Q

normal mean pressure in the pulmonary venous circulation

A

6-12

135
Q

what does the pulmonary venous pressure waveform look like

A

CVP/PA wedge

136
Q

resistance is ______ in the pulmonary circulation than systemic circulation

A

more evenly spread

137
Q

which zone is PA>Pa>Pv

A

zone 1

138
Q

which zone is Pa>PA>Pv

A

zone 2

139
Q

which zone is Pa>Pv>PA

A

zone 3

140
Q

which zone is blood flow tamponaded by alveolar pressure

A

zone 1

141
Q

which zone is ventilated but not perfused (alveolar dead space)

A

zone 1

142
Q

what conditions does zone 1 occur

A

reduced arterial pressure (septic shock, hemorrhage)
alveolar pressure elevated (positive pressure ventilation)

143
Q

what is the waterfall effect

A

arterial pressure is increasing down the zone but alveolar pressure stays the same so the pressure difference responsible for flow increases moving downward

144
Q

which zone is blood flow determined by the difference between arterial and alveolar pressures

A

zone 2

145
Q

which zone is flow determined by the arterial-venous pressure difference

A

zone 3

146
Q

in zone 3, the pressure inside capillaries _____ down the zone, while the pressure outside (alveolar) remains constant which results in _________

A

increases
rising transmural pressure

147
Q

3 causes of zone 4

A

PE
mitral stenosis
pulm. edema

148
Q

what is zone 4

A

lung has positive interstitial pressure

149
Q

in zone 4, flow depends on what

A

difference between arterial pressure and interstitial pressure

150
Q

which zone has a high V/Q ratio

A

zone 1

151
Q

which zone has a low V/Q ratio

A

zone 4

152
Q

define absolute pulmonary shunt
whats the V/Q ratio?

A

perfusion with no ventilation
V/Q=0

153
Q

what are the O2 and CO2 levels in absolute pulmonary shunt

A

O2 decreased
CO2 increased

154
Q

define absolute physiological dead space
whats the V/Q ratio?

A

ventilation with no perfusion
V/Q= infinity

155
Q

what is the average V/Q

A

0.8

156
Q

define hypoxemia

A

low concentration of o2 in the arterial blood

157
Q

define hypoxia

A

inadequate delivery of o2 to the tissue

158
Q

example of hypoxemia without hypoxia

A

mountain climber at the summit of Mt. Everest

159
Q

example of hypoxia without hypoxemia

A

cardiogenic shock

160
Q

4 causes of hypoxemia

A

hypoventilation
diffusion limitation
shunt
ventilation-perfusion inequality

161
Q

2 causes of hypercapnia

A

hypoventilation
ventilation-perfusion inequality

162
Q

causes of hypoventilation

A

drugs
damage to the chest wall
weakness/paralysis of resp muscles
high resistance to breathing
morbid obesity

163
Q

how does obesity cause hypoventilation

A

affects both central resp drive and resp mechanics

164
Q

if alveolar ventilation is halved, PCO2 is _____

A

doubled

165
Q

alveolar gas equation CO2

A

PCO2= (VCO2/VA)*K
VCO2= CO2 production
VA= alveolar ventilation
K= constant

166
Q

how is hypoxemia due to hypoventilation reversed?

A

increasing inspired o2 content

167
Q

define diffusion limitation

A

decreased o2 diffusion through the blood-gas barrier

168
Q

2 causes of diffusion limitation

A

decreased SA (ARDS)
decreased permeability (pulm. fibrosis)

169
Q

2 causes of shunt

A

intracardiac right-to-left shunt
blood passes through a diseased or collapsed lung

170
Q

what is the normal shunt fraction in healthy adults at RA

A

0-1%

171
Q

what is the only cause of hypoxemia that is not responsive to an increase in inspired o2

A

shunt

172
Q

why is there not an increase in PCO2 in shunting

A

chemoreceptors sense any elevation of arterial PCO2 and respond by increasing ventilation
this reduces the PCO2 of the unshunted blood until the arterial PCO2 is normal/ low

173
Q

alveolar gas equation describes what

A

the concentration of gases in the alveolus and thus the effectiveness of gas exchange
can be used to calculate the tension-based indices of oxygenation such as A-a gradient or a/A ratio

174
Q

What is the A-a gradient

A

magnitude of the gradient between the alveolus and the arterial blood

175
Q

what is a normal A-a gradient at 21% FiO2

A

7mmHg in young
14mmHg in old

176
Q

how is hypercapnia corrected in V/Q mismatch

A

increase ventilation

177
Q

how is hypoxemia corrected in V/Q mismatch

A

increase FiO2