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Human physiology > Chapter 8: Neurons - Cellular & Network Properties > Flashcards

Chapter 8: Neurons - Cellular & Network Properties Flashcards

1
Q

consists of brain and spinal cord

A

central nervous system

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2
Q

Receives and processes information form sensory organs and the viscera to determine the state of the external and internal environment

A

central nervous system

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3
Q

consists of afferent and efferent neurons

A

peripheral nervous system

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4
Q
  • transmit sensory and visceral info to CNS

- input

A

afferent neurons

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5
Q
  • are either somatic (control skeletal muscle) or autonomic (control smooth & cardiac muscle, endocrine glands)
  • output
A

efferent neurons

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6
Q

divided into sympathetic and parasympathetic systems

A

autonomic nervous system

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7
Q

excitable cells

A

neurons

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8
Q

support cells

A

glial cells

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9
Q
  • cell body

- contains nucleus and most organelles

A

soma

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10
Q

reception of incoming information

A

dendrites

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11
Q

Transmits electrical impulses called action potentials

A

axon

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12
Q

Where axon originates and action potentials are initiated

A

axon hillock

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13
Q
  • synaptic knob, synaptic bouton

- Releases neurotransmitter

A

axon terminal

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14
Q

what are the components of a neuron?

A
  • soma
  • dendrites
  • axon
  • axon hillock
  • axon terminal
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15
Q 
-have a single
process called the
axon
-During
development, the
dendrite fused with
the axon.
A

pseudounipolar neurons

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16
Q 
have two
relatively equal
fibers extending
off the central
cell body
A

bipolar neurons

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17
Q

have

no apparent axon

A

anaxonic CNS internuerons

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18
Q

highly branched but lack

long extensions

A

multipolar CNS interneurons

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19
Q

how many dendrites does a typical multipolar efferent neuron have?

A

has five to seven
dendrites, each branching
four to six times

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20
Q

what are the forms of axonal transport?

A
  • anterograde transport

- retrograde transport

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21
Q

transport from soma to axon terminal

A

anterograde transport

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22
Q

-transport from axon to soma
-microtubules & neurofilaments
-Slow: 0.5–40 mm/day
-Fast: 100–400 mm/day
~Vesicles
~kinesins

A

retrograde transport

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23
Q

what are the steps of fast axonal transport?

A
  1. peptides made on rough ER & packaged by Golgi apparatus
  2. fast axonal transport walks vesicles & mitochondria along microtubule network
  3. vesicle contents released by exocytosis
  4. synaptic vesicle recycling
  5. retrograde fast axonal transport
  6. old membrane components digested in lysosomes
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24
Q

the region where the axon terminal meets the target cell

A

synapse

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25
Q

what are presynaptic and postsynaptic cells separated by?

A

synaptic cleft

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26
Q

a chemical signal diffuses across the synapse

A

chemical synapse

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27
Q

gap junctions connect pre and postsynaptic cells (bidirectional and faster)

A

electric synapses

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28
Q
  • provide structural integrity, chemical, and anatomical support of neurons
  • “glue”
  • 90% of cells
A

glial cells

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29
Q

what are the 2 types of glial cells of the peripheral nervous system?

A
  1. schwann cells

2. satellite cells

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30
Q

wrap around axon and form insulating myelin sheaths

A

schwann cells

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31
Q
  • gaps in the insulation of myelin sheaths

- section of unmyelinated axon membrane

A

nodes of ranvier

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32
Q

form supportive capsules around the cell body, regulate the chemical environment

A

satellite cells

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33
Q

what are the 4 types of glial cells of the central nervous system?

A
  1. Oligodendrocytes
  2. Astrocytes
  3. Microglia
  4. Ependymal cells
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34
Q

form myelin sheath

A

Oligodendrocytes

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35
Q

take up and release chemicals, feed neurons, water-K+ balance, and part of blood-brain-barrier

A

astrocytes

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36
Q

provide immune defense by removing damaged cells and foreign invaders

A

microganglia

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37
Q

form the barrier between fluid compartments of the CNS and are a source of stem cell

A

ependymal cells

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38
Q

consists of multiple layers of cell membrane

A

myelin

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39
Q

difference in voltage between two points

A

potential difference (E)

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40
Q

difference in voltage across the plasma membrane; always given in terms of voltage inside the cell relative to voltage outside the cell

A

membrane potential

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41
Q

a relatively small change in the membrane potential produced by a stimulus that triggers the opening or closing of ion channels

A

graded potential

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42
Q

graded potentials produced in the post-synaptic cell in response to neurotransmitters binding to receptors

A

synaptic potential

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43
Q

graded potentials produced in response to a stimulus acting on a sensory receptor

A

receptor potential

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44
Q

a large, rapid change in the membrane potential produced by depolarization of an excitable cell’s plasma membrane to threshold

A

action potential

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45
Q

the membrane potential that counters the chemical forces acting to move an ion across the membrane, thereby putting the ion at………

A

equilibrium potential

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46
Q

what are the 2 factors needed to determine the resting membrane potential?

A
  1. ion concentration gradients
  2. membrane permeability to these ions
    ~ion channels
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47
Q

what is needed to establish the equilibrium potential?

A
  1. hypothetical cell
  2. ion distribution
    ~outside cell= sodium and chloride
    ~inside cell= potassium and organic anions
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48
Q

what is the potassium equilibrium potential?

A
  • K+ chemical driving force= out of cell

- K+ diffuses out of cell

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49
Q

what happens as K+ diffuses out of the cell?

A

the inside of the cell becomes more negative

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50
Q

what pulls K+ back into the cell?

A

electrical driving force

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51
Q
  • opposite in direction

- equal in magnitude

A

chemical and electrical driving forces

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52
Q

when is an ion at equilibrium?

A
  • when there is no net force for it to move across the membrane
  • Chemical force = negative electrical force
  • Electrochemical force = 0
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53
Q

when is potassium at equilibrium?

A

When membrane potential = –90 mV

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54
Q

what is the sodium equilibrium potential?

A
  • Na+ chemical driving force: into the cell

- Na+ diffuses into cell

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55
Q

what happens as Na+ diffuses into the cell?

A

the inside of the cell becomes less negative (positive)

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56
Q

what pushes Na+ out of the cell?

A

electrical driving force

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57
Q

what are the 2 forces acting on Na+?

A
  • chemical: to move in

- electrical: to move out

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58
Q

*electrochemical force
~intially in, due to stronger chemical force
~but electrical force continues to increase

A

net force

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59
Q

when is sodium at equilibrium?

A

When membrane potential = +60 mV

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60
Q

is a neuron more permeable to potassium or sodium?

A

25x more permeable to potassium

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61
Q

what is the ion distribution of a neuron?

A
  • outside cell: sodium and chloride

- inside cell: potassium and organic anions

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62
Q

what are the chemical driving forces for the resting potential of a neuron?

A
  • K+ out of cell

- Na+ into cell

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63
Q

in what ratio does K+ and Na+ enter and leave the cell?

A

more K+ leaves the cell than Na+ enters

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64
Q

what is the result of more K+ leaving the cell than Na+ entering?

A

inside of cell becomes negative

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65
Q

what do the electrical forces for the resting potential of a neuron do?

A
  • Na+ into cell

- K into cell

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66
Q

what do the electrical forces of the resting potential for a neuron result in?

A
  • K+ outflow slows

- Na+ inflow speeds up

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67
Q

inflow of Na+ is balanced by outflow of K+

A

steady state develops

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68
Q

what is the resting membrane potential of a neuron?

A

-70 mV

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69
Q

-Predicts membrane potential that results from the contribution of all ions that can cross the membrane

A

Goldman-Hodgkin-Katz (GHK) Equation

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70
Q

determined by the combined contributions of the concentration gradient times the membrane permeability for each ion

A

Resting membrane potential

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71
Q

maintains the resting potential of a neuron

A

sodium pump

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72
Q

what is the resting membrane potential closer to?

A

the potassium equilibrium potential

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73
Q

what happens when the membrane potential is not at equilibrium for an ion?

A
  • electrochemical force is not 0
  • net force acts to move the ion across the membrane in the direction that favors its being at equilibrium
  • strength of the net force increases the farther away the membrane potential is from the equilibrium potential
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74
Q

what are the forces on K+?

A
  • Resting potential = –70 mV
  • EK = –94 mV
  • Vm is 24 mV less negative than EK
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75
Q

into the cell (lower)

A

electrical force on K+

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76
Q

out of the cell (higher)

A

chemical force on K+

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77
Q

net force on K+ is weak

A

K+ flows out of the cell, but the membrane is highly permeable to K+

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78
Q

what are the forces on Na+?

A
  • Resting potential= –70 mV
  • ENa = +60 mV
  • Vm is 130 mV less negative than ENa
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79
Q

into the cell

A

electrical force on Na+

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80
Q

into the cell

A

chemical force on Na+

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81
Q

net force on Na+ is strong

A

Na+ flows into the cell, but the membrane has low permeability to Na+

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82
Q

high force, low permeability

A

Small Na+ leak at rest

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83
Q

low force, high permeability

A

Small K+ leak at rest

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84
Q

returns Na+ and K+ to maintain gradients

A

sodium pump

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85
Q

20% of the resting membrane potential is directly due to……….?

A

Na+/K+-ATPase

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86
Q
  • Electrogenic: 3 Na+ out, 2 K+ in

- Net: +1 out

A

Na+/K+ pump

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87
Q

80% of resting membrane potential is indirectly due to…….?

A

Na+/K+-ATPase

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88
Q

-produces concentration gradients
~Na+= high outside, low inside
~K+=low outside, high inside

A

80% of resting membrane potential is indirectly due to Na+/K+-ATPase

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89
Q
  • a difference in potential across the membrane

- membrane is polarized

A

membrane potential

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90
Q

-70 mV

A

resting potential

91
Q

a change to a more negative value

A

Hyperpolarization

92
Q

a change to a less negative value

A

Depolarization

93
Q

when the membrane potential returns to resting

A

Repolarization

94
Q

what are the components of a resting membrane potential?

A
  1. ion concentration gradients

2. membrane permeability to these ions

95
Q

what are the gated channels that control ion permeability?

A
  • mechanically gated
  • chemically gated
  • voltage gated
96
Q

varies from one channel type to another

A

threshold voltage

97
Q

small changes in membrane potential that occur when ion channels open or close in response to a stimulus

A

graded potentials

98
Q

such as neurotransmitter molecules binding to receptors on the dendrite or cell body of a neuron

A

chemical stimuli

99
Q

such as touch or light acting on a sensory receptor

A

sensory stimuli

100
Q

varies according to the strength of the stimuli

A

The magnitude of the change in membrane potential

101
Q

occur in the membranes of excitable tissue (nerve or muscle) in response to graded potentials that reach threshold

A

action potentials

102
Q

Once initiated, it is capable of being propagated long distance along the length of an axon without any decrease in strength

A

action potential

103
Q

lose strength as they move through the cell due to current leak and cytoplasmic resistance

A

graded potentials

104
Q

if strong enough, graded potentials reach the……?

A

the trigger zone in the axon hillock and initial segment

105
Q

the ability to fire an action potential

A

Cell’s excitability

106
Q

depolarizing

A

excitatory

107
Q

hyperpolarize

A

inhibitory

108
Q
  • a graded potential starts above threshold (T) at its initiation point but decreases in strength as it travels through the cell body
  • at the trigger zone, it is below threshold and, therefore, does not initiate an action potential
A

subthreshold graded potential

109
Q

a stronger stimulus at the same point on the cell body creates a graded potential that is still above threshold by the time it reaches the trigger zone, so an action potential results

A

suprathreshold graded potential

110
Q

when is an action potential triggered?

A

if the membrane threshold at the axon hillock is depolarized to threshold

111
Q

what happens if the potential is below threshold?

A

no action potential will occur

112
Q

adding effects of graded potentials

A

summation

113
Q
  • are graded potentials

- can be summed

A

IPSPs and EPSPs

114
Q

what are the types of summation?

A
  1. temporal

2. spatial

115
Q
  • type of summation

- one synapse through time

A

temporal

116
Q
  • type of summation

- several synapses at the same time

A

spatial

117
Q

what is the degree of depolarization at the axon hillock signaled by?

A

frequency of action potentials

118
Q
  • affects depolarization

- influences frequency of action potentials

A

summation

119
Q

More action potentials result in more neurotransmitter released, which leads to……?

A

a greater IPSP or EPSP in the next neuron

120
Q

The degree of depolarization at the axon hillock is signaled by the frequency of action potentials

A

frequency coding

121
Q

The regulation of communication across a synapse

A

presynaptic modulation

122
Q

what are the two modulatory synapses?

A
  • presynaptic facilitation

- presynaptic inhibition

123
Q

the high-speed movement of a action potential along an axon

A

conduction

124
Q

how do action potentials move down an axon?

A

Not a single action potential (AP) that moves down the axon but rather many replenished AP’s

125
Q

what do axons travelling down an axon form?

A

a wave of electrical signal at constant amplitude

126
Q

also known as nerve spikes

A

action potentials

127
Q

the principle that the strength by which a nerve or muscle fiber responds to a stimulus is independent of the strength of the stimulus. If that stimulus exceeds the threshold potential, the nerve or muscle fiber will give a complete response; otherwise, there is no response

A

all-or-none law

128
Q

what happens during the conduction of an action potential?

A
  • each section of the membrane is a different phase of the action potential
  • a wave of electrical current passes down the axon
  • each section of the axon is experiencing a different phase of the action potential
129
Q

what are the steps of an action potential?

A
  1. resting membrane potential
  2. depolarizing stimulus
  3. Membrane depolarizes to threshold.
    Voltage-gated Na+ and K+
    channels begin to open.
  4. rapid Na+ entry depolarizes cell
  5. K+ moves from cell to extracellular fluid
  6. K+ channels remain open and
    additional K+ leaves cell, hyperpolarizing it.
  7. Voltage-gated K+ channels close,
    less K+ leaks out of the cell.
  8. Cell returns to resting ion permeability
    and resting membrane potential.
130
Q

How do you stop depolarization and this positive feedback loop?

A

Voltage-gated sodium channels have two gates

131
Q

what are the two voltage-gated sodium channels?

A
  • activation gates

- inactivation gates

132
Q
  • responsible for opening sodium channels during the depolarization phase of AP
  • closes the channel at the resting membrane potential
  • Na+ enters the cell
A

activation gates

133
Q
  • (0.5 msec delay)responsible for the closing of sodium channels during the repolarization phase of AP
  • Na+ entry stops
A

inactivation gates

134
Q

what happens during repolarization caused by K+ leaving the cell?

A

the activation and inactivation gates reset to their original positions

135
Q
  • due to Na+ gates resetting
  • Potential delay of 1-2 msec. between action potentials independent of intensity of trigger
  • no stimulus can trigger another action potential
A

absolute refractory period

136
Q

prevents backward conduction

A

refractory period

137
Q

-follows an absolute refractory period
-only a larger-than-normal stimulus can initiate a new action
potential

A

relative refractory period

138
Q

-spreads along adjacent sections of axon by local current flow

A

positive charge

139
Q

-causes new section of the membrane to depolarize

A

local current flow

140
Q

what are the phases of an action potential?

A
  1. rising phase
  2. peak
  3. falling phase
141
Q

what happens during the conduction of an action potential?

A 
1. A graded potential above 
threshold reaches the trigger zone
2. Voltage-gated Na+ channels
open, and Na+ enters the axon. 
3. Positive charge flows into 
adjacent sections of the axon 
by local current flow. 
4. Local current flow from the 
active region causes new sections
of the membrane to depolarize.
5. The refractory period prevents 
backward conduction. Loss of K+ 
from the cytoplasm repolarizes 
the membrane.
142
Q

what is the speed of an action potential in a neuron influenced by?

A
  • diameter of axon

- resistance of axon membrane to ion leakage out of the cell

143
Q

how does the diameter of an axon affect the speed of an action potential?

A

larger axons are faster

144
Q

how does the resistance of axon membrane to ion leakage out of the cell affect the speed of an action potential?

A
  • myelinated axons are much faster

- saltatory condution between nodes of ranvier

145
Q

the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials

  • Action potentials appear to jump from one node of Ranvier to the next
  • Only the nodes have voltage-gated Na+ channels.
A

saltatory conduction

146
Q

reduce or block conduction when current leaks out of the previously insulated regions between the nodes

A

demyelinating diseases

147
Q

how can chemical factors alter action potentials?

A

-Binding of chemicals (neurotoxins, anesthetics) to Na+, K+, or Ca+ can alter the conduction of action potentials.
~blocking votage gated Na+ channels
-procaine hydrochloride (novacaine)
-tetrdotoxin (fugu toxin)
-K+ concentrations can also cause abnormal electrical activity in the nervous system
~hyperkalemia vs hypokalemia

148
Q 
increased
blood K+ concentration, 
brings the membrane closer 
to the threshold. Now a 
stimulus that would normally
be subthreshold can 
trigger an action potential.
A

hyperkalemia

149
Q 
decreased
blood K+ concentration, 
hyperpolarizes the membrane
and makes the neuron less
likely to fire an action potential
in response to a stimulus that
would normally be above the
threshold.
A

hypokalemia

150
Q

what is the type of signal in a graded potential?

A

input signal

151
Q

where do graded potentials occur?

A

dendrites and cell body

152
Q

what are the types of gated ion channels in neurons?

A
  • mechanically gated
  • chemically gated
  • voltage gated
153
Q

what are the ions involved in graded potential?

A

Na+, K+, Ca^2+

154
Q

what is the signal type of graded potentials?

A
  • depolarizing (Na+)

- hyperpolarizing (Cl-)

155
Q

what is the strength of the signal of a graded potential?

A

-depends on the initial stimulus, but it can be summed

156
Q

what initiates the signal of a graded potential?

A

entry of ions through gated channels

157
Q

what are the unique characteristics of a graded potential?

A
  • no minimum level required to initiate
  • two signals coming together in time will sum
  • initial stimulus strength is indicated by frequency of a series of action potentials
158
Q

what type of signal is an action potential?

A

regenerating conduction signal

159
Q

where does an action potential occur?

A

trigger zone through axon

160
Q

what are the types of gated channels involved in action potentials?

A

voltage gated channels

161
Q

what are the ions involved in action potentials?

A

Na+ and K+

162
Q

what type of signal is an action potential?

A

depolarizing

163
Q

what is the strength of a signal of an action potential?

A

all or none phenomenon; cannot be summed

164
Q

what initiates the signal of an action potential?

A

above-threshold graded potential at the trigger zone opens ion channels

165
Q

what are unique characteristics of an action potential?

A
  • threshold stimulus required to initiate

- refractory period; two signals too close together in time cannot sum

166
Q

what do neurons communicate at?

A

synapses

167
Q

pass electrical signals through gap junctions (cytoplasm continuous)

A

electrical synapses

168
Q
  • signal can be bi-directional
  • synchronizes the activity of a network of cells
  • cardiac, smooth muscle, glial cells, CNS
A

electrical synapses

169
Q
  • use neurotransmitters that cross synaptic clefts

- Make up majority of synapse in the nervous system

A

chemical synapses

170
Q
  • act at short distances
  • released by a neuron
  • diffuse across a narrow cleft to effect postsynaptic cell
A

neurotransmitters

171
Q
  • act over long distances
  • released by neurons into the circulation
  • exerts its effects on distant peripheral targets
A

neurohormones

172
Q

what are the two types of neurocrine receptors?

A
  1. receptor channels (ionotropic receptors)

2. metabotropic receptors

173
Q
  • mediate rapid response

- alter ion flow across membranes

A

receptor channels (ionotropic receptors)

174
Q
  • G protein-mediated receptors
  • mediate slower responses due to 2nd messenger system
  • some open or close ion channels
A

metabotropic reeceptors

175
Q

all neurotransmitters except……….., bind to specific receptors

A

nitric oxide

176
Q

allows the same neurotransmitter to have different effects in different tissues

A

when receptors have multiple subtypes

177
Q

either mimic or inhibit activity by binding to receptors

A

agonist and antagonist molecules

178
Q

what are the seven classes of neurocrines by structure?

A
  1. Acetylcholine (Ach)- derived from Acetyl CoA
  2. Amines (biogenic amines)- derived from a single amino acid
  3. amino acids
  4. peptides
  5. purines
  6. gases - NO, CO, H2S
  7. lipids
179
Q

Neurons that secrete Acetylcholine and receptors that bind it

A

cholinergic

180
Q

what is the site of release of acetylcholine?

A
  • CNS and ANS synapses

- neuromuscular junctions

181
Q

what is the effect of acetylcholine?

A
  • Excitatory in the CNS and neuromuscular junctions

- Inhibitory or excitatory in ANS synapses

182
Q

what is the agonist of acetylcholine?

A

nicotine

183
Q

what is the antagonist of acetylcholine?

A

curare (plant derived)

184
Q

how is acetylcholine synthesized?

A
  • Acetyl CoA + choline —> acetylcholine + CoA
  • synthesized in axon terminal
  • Choline acetyl transferase (CAT) = enzyme for synthesis
185
Q

how is acetylcholine broken down?

A
  • Acetylcholine —> acetate + choline
  • occurs in synaptic cleft
  • Acetylcholinesterase (AChE) = enzyme of degradation
186
Q

what are the cholinergic receptors of acetylcholine?

A
  • nicotinic

- muscarinic

187
Q
  • receptor of acetylcholine
  • on skeletal muscle, in autonomic division of PNS and CNS
  • monovalent cation channels –> Na+ & K+
A

nicotinic

188
Q
  • receptor of acetylcholine
  • in CNS and autonomic parasympathetic division of the PNS
  • G protein coupled receptors
A

muscarinic

189
Q
  • derived from tryptophan

- Involved in regulating sleep, alertness, thermoregulation, and mood

A

amines (serotonin)

190
Q

what is the site of release of amines (serotonin)?

A

CNS synapses

191
Q

what is the effect of serotonin?

A
  • inhibitory and excitatory

- serotonergic receptors

192
Q
  • used to treat depression

- block serotonin symporters

A

SSRIs (prozac & zoloft)

193
Q
  • derived from tyrosine
  • Highly concentrated in substantia nigra control of skeletal muscles, involved in elevation of mood, motivation, and reward
A

amines (dopamine)

194
Q

what is the site of release of dopamine?

A

Selected CNS synapses, some ANS synapses

195
Q

what is the effect of dopamine?

A

inhibitory and excitatory

196
Q

blocks dopamine transporters, which increases levels in synaptic cleft

A

cocaine

197
Q
  • derived from tyrosine
  • involved in dreaming, waking, and mood, excited cardiac muscle, excite or inhibit smooth muscle and glands
  • Adrenergic Receptors (alpha and beta)
A

amines (norepinephrine/epinephrine)

198
Q

what is the site of release of norepinephrine/epinephrine?

A

Selected CNS synapses, some ANS synapses

199
Q

what is the effect of norepinephrine/epinephrine?

A

inhibitory and excitatory

200
Q

what are some important amino acids?

A
  • glutamate
  • glycine
  • GABA (ƴ-aminobutyric acid)
201
Q

accounts for about 75% of all excitatory synaptic transmission in the brain, involved in learning and memory

A

glutamate

202
Q
  • inhibitory brain, most common inhibitory neurotransmitter in the spinal cord
  • enhances the excitatory effect of glutamate
A

glycine

203
Q

most common inhibitory neurotransmitter in the brain

A

GABA(ƴ-aminobutyric acid)

204
Q

peptide neurotransmitters involved in pain

A

substance P and opioid peptides

205
Q

AMP and ATP bind to receptors in the CNS

A

purine neurotransmitters

206
Q

gas neurotransmitters that diffuse in the cells

A

NO, CO, H2S

207
Q

Eicosanoids, endogenous ligands for cannabinoid receptors

A

lipid neurotransmitters

208
Q

what happens when an action potential reaches an axon terminal?

A

opens voltage-gated Ca+ channels due to depolarization

209
Q

once the Ca+ channels are open what happens?

A

Ca+ enters axon terminal and initiates exocytosis of synaptic vesicles containing neurotransmitter
-H+ dependent antiporters. Exchange H+ for neurotransmitters in vesicle

210
Q

-rapid removal or inactivation in the synaptic cleft

A

termination of neurotransmitter activity

211
Q

what happens during the rapid removal or inactivation in the synaptic cleft?

A
  • diffusion out of the synaptic cleft into the ECF
  • enzymatic breakdown
  • Intact or broken down neurotransmitters are taken up by presynaptic axon terminal or glial cells
212
Q

determines how much neurotransmitter is released

A

frequency of action potentials

213
Q

releases little neurotransmitter

A

weak stimulus

214
Q

causes more action potentials and releases more neurotransmitter

A

strong stimulus

215
Q

what is involved in the integration of neural information transfer?

A
  • divergent and convergent (branching) pathways at synapses

- synaptic plasticity

216
Q

a change of activity at the synapses (i.e. enhance or decrease activity)

A

synaptic plasticity

217
Q

one presynaptic neuron branches to affect a larger number of postsynaptic neurons

A

divergent pathway

218
Q

many presynaptic neurons provide input to influence a smaller number of postsynaptic neurons

A

convergent pathway

219
Q

nearly covered with synapses providing input from other neurons.

A

cell body of a somatic motor neuron

220
Q

Which of the following glial cells become part of the blood-brain barrier?

A

astrocytes

221
Q

If the ECF K+ concentration increases from 3 mM to 5 mM, what happens to the resting membrane potential of cells?

A

it becomes less negative

222
Q

A neuron under the influence of a neurotransmitter that opens K+ channels will……

A
  • become hyperpolarized

- be less likely to fire an action potential

223
Q

What effect does hyperkalemia, an increase in plasma K+ concentration, have on the resting membrane potential of neurons?

A
  • less K+ leaves the cell so membrane potential becomes less negative.
  • Shifts it closer to threshold so the neuron is more likely to depolarize.

Human physiology (17 decks)

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