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126 > Chpt 3: Excitable Cells and Neural Communication > Flashcards

Chpt 3: Excitable Cells and Neural Communication Flashcards

1
Q

Membrane potential def

A

refers to the difference in the electrical potential b/w icf and ecf

or

separation of opposite charges across the plasma membrane

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2
Q

does membrane potential occur in all human and plant cells

A

yes

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3
Q

how is membrane potential measured

A

millivolts (mV)

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4
Q

example of excitable cells

A

nerve and muscle cells

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5
Q

when do nerves and muscles rest?

A

during sleep, but continue to make or reserve atp

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6
Q

nerve and muscle cell ability

A

can produce rapid, transit changes in their membrane potential when excited

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7
Q

Resting membrane potential def

A

constant membrane potential present in cells of non-excitable tissues

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8
Q

what mV does resting potential rest at

A

-70mV

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9
Q

effects of Na-K pump in membrane potential

A

-contributes by its unequal transports of positive ions (3 Na and 2 K)

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10
Q

what restores mp and how

A

Na-K pump using a carrier and ATP

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11
Q

how is concentration measured?

A

millimoles/liters (mM/L)

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12
Q

concentration of Na+ in ecf

A

150mM/L

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13
Q

concentration of Na+ in icf

A

15mM/L

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14
Q

relative permeability of Na+

A

1

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15
Q

concentration of K+ in ecf

A

5mM/L

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16
Q

concentration of K+ in icf

A

150mM/L

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17
Q

relative permeability of K+

A

50-75

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18
Q

what ions are involved in the production of membrane potential?

A

Na+ and K+

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19
Q

what ions are present but not involved with mp

A

A- (carbohydrates, amino acids, proteins)
Cl-
HCO3-

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20
Q

what ion is the first to take charge in creating an electrical signal?

A

Na+

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21
Q

what ion is the most permeable/ leaky

A

K+

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22
Q

what ion creates the opposite concentration gradient?

A

K+

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23
Q

A- concentration in icf

A

65mM/L

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24
Q

Cl- concentration in ecf

A

100mM/L

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25
Q

what ion moves around but doesn’t create an electrical potential

A

Cl- and HCO3-

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26
Q

HCO3- concentration in ECF

A

30mM/L

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27
Q

excitable cells meaning

A

cells that change their resting potential to produce electrical signals when excited

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28
Q

Polarization

A

any state when mp is anywhere but at 0mV

staying at -70mV/ being negative

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29
Q

depolarization

A
  • less polarized (less negative) than at rp

- moving towards 0mV after a stimulus has reached the threshold

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30
Q

repolarization

A
  • membrane returns to rp (-70mV)

- becoming negative

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31
Q

hyperpolarization

A
  • membrane becomes more polarized than rp

- more negative

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32
Q

what is the mV at hyperpolarization

A

below -70mV and can go down to -90mV

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33
Q

upward deflection =

A

decrease in potential (icf is less - )

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34
Q

downward deflection =

A

increase in potential (icf is more - )

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35
Q

what creates electrical signals

A

channels (many diff kinds)

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36
Q

voltage-gated channels

A
  • electrical current will open them
  • at rest = gate is closed
  • excited = gate is open
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37
Q

what determines when voltage-gated channels open/close?

A

changes in membrane potential

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38
Q

chemically gated channels

A

open under command of chemical signals

~ neurocrines, paracrines, hormones

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39
Q

mechanically gated channels

A
  • respond to stretching or mechanical deformation

- need pressure or touch to open

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40
Q

thermally gated channels

A
  • respond to changes in temp
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41
Q

what restores resting potential?

A

NA-K pump

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42
Q

what are the two kinds of potential changes?

A

graded potential

action potential

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43
Q

where do graded potentials occur?

A

small, specialized region of the membrane

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44
Q

what type of change occurs with graded potential?

A

-small changes in membrane potential/ electrical state

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45
Q

how does graded potential progress?

A

dies down

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46
Q

which potential change goes in both directions?

A

graded potential

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47
Q

how to produce an electrical signal

A

-stimulus occurs, reaches threshold, depolarization ocurs

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48
Q

what do the magnitude and duration depend on in graded potential?

A

-strength and duration of triggering event (aka stimulus)

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49
Q

what happens with a stronger triggering event

A

more gated channels = more Na/ + charges in = depolarization

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50
Q

why does the potential in graded potential die down?

A
  • K+ leaking out

- cytoplasm = bad conductor `

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51
Q

current def

A

any flow of electrical chargers, current follows direction of + charges

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52
Q

examples of graded potential

A
  • postsynaptic
  • receptor
  • end-plate
  • pacemakers
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53
Q

where does end plate graded potential occur?

A
  • occurs in neuromuscular junction

between neuron and muscle

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54
Q

pace maker graded potential meaning

A

-set/make their own pace

55
Q

where is a pacemaker graded potential found?

A

muscles

56
Q

Action Potential location in neruon

A

cell membrane

57
Q

ap time

A

brief, large, rapid

58
Q

what is the magnitude of change in AP?

A

100mV

59
Q

Action Potential description

A
  • doesnt decrease in strength

- long-distance signals

60
Q

what potential is involved with positive feedback

A

action potential

61
Q

rising phase cause

A

Na+ influx which causes depolarization

62
Q

peak meaning

A

+30 mv is reaching, K+ efflux begins

63
Q

falling phase cause

A
  • K+ efflux, repolarization occurs
64
Q

threshold potential

A
  • triggered by an increase in Na+ permeability
  • minimum stimulus require to go beyond
  • rests at -50mV
65
Q

activation gate structure

A

latch like

66
Q

inactivation gate structure

A

ball and chain

67
Q

when does the inactivation gates begins to close?

A

at peak

68
Q

undiminished movement

A

ensures ap will cover the entire membrane

69
Q

what ensures undiminished movement?

A

refractory period

70
Q

refractory period

A
  • period of time followed by an ap
  • marked by decreased excitabtily
  • another ap will not occur
71
Q

absolute period

A
  • ap is occurring in present time, so another one cant occur
  • all of depolarization and most of repolarization
  • Na gates are closed
72
Q

Relative period

A
  • last part of repolarization and hyperpolarization
  • Na+ gates closed, some K are open
  • resting phase
73
Q

can another ap occur during the relative period

A

yes, if the stimulus is urgent or stronger than the first

74
Q

consequences of refractory period

A
  • all or none principle

- undirectional

75
Q

movement of ap propagates from ___ to ___

A

axon hillock to axon terminal

76
Q

collaterals

A

side branches of axon

77
Q

input zone

A

signals are received

78
Q

dendrite/ dendrite zone

A

gather stimulus

79
Q

cell body

A

contains nucleus

80
Q

trigger zone location

A

axon hillock

81
Q

trigger zone function

A

ap is initiated

82
Q

conducting zone location

A

axon

83
Q

conducting zone function

A

conducts ap in undiminishing fashion

84
Q

output zone location

A

axon terminal

85
Q

output zone structure

A

releases a neurotransmitter that influences other cell

86
Q

how does conduction/ap propagate through nerve cells?

A

contigous conductions and saltatory conduction

87
Q

contigous conduction location

A

in unmyelinated neurons

88
Q

contigous conduction process

A

ap spreads along every portion of membrane

89
Q

speed of contigous conduction

A

0.7m/s in digestive system neurons

90
Q

energy consumption of saltatory conduction

A

conserves energy, since channels dont have to reset

91
Q

how to increase speed of ap

A
  • large diameter

- myelination (50x faster)

92
Q

myelin function

A
  • used to insulate

- makes saltatory conduction possible

93
Q

what is myelin composed of?

A

lipids

94
Q

which cell forms myelin in the CNS?

A

oligodendrocytes

95
Q

where are Schwann cells found + function

A

PNS and make myelin

96
Q

synapses

A

junction between 2 neurons

97
Q

synaptic cleft

A

area between neurons

98
Q

presynaptic neuron

A

takes message toward synapse

99
Q

postsynaptic neuron

A

-takes message away from synapse

100
Q

synaptic vesicle

A

-stores neurotransmitters

101
Q

synaptic knob

A
  • contains synaptic vesicles

- touches postsynaptic neuron

102
Q

does contignous conduction use atp?

A

yes, cuz membrane resets each time

103
Q

saltatory conduction location

A

in myelinated fibers

104
Q

saltatory conduction propagation process

A

-impulses jump over sections of the fibers covered with insulating myelin

105
Q

which conduction is faster

A

saltatory conduction, it is 120m/s in muscle cell

106
Q

types of synapse

A

excitatory and inhibitory

107
Q

excitatory synapse function

A

creates small depolarization

108
Q

inhibitory synapse function

A

leads to small hyperpolarization

109
Q

what does more negative membrane potential mean

A

harder to make ni

110
Q

neural summation definiton

A

effect of 2 different potentials (inhibitory or excitatory) coming together

111
Q

what does neural summation create

A

grand postsynaptic potential

112
Q

what does grand postsynaptic potential include

A

temporal or spacial summation

113
Q

what dictates grand postsynaptic potential

A

rates of presynaptic neutrons firing

114
Q

temporal summation

A

several epsp occurring very close in time

115
Q

epsp

A

excitatory postsynaptic potential

116
Q

ipsp

A

inhibitory postsynaptic potential

117
Q

grand postsynaptic potential depends on

A

sum of activity in all presynaptic inputs and determines if a neuron will undergo ap

118
Q

spacial summation

A

-2 different excitatory or inhibitory add up in a space, 2 diff inputs from diff areas in one space

119
Q

cancellation of ipsp and epsp occurs

A

-inhibitory and excitatory signal cancel each other

120
Q

what is missing in Parkinson’s

A

dopamine in bASal gangli

121
Q

result of Parkinson’s

A

muscular rigidity + involuntary tremors

122
Q

cocaine use causes too much off..

A

dopamine in the brain

123
Q

tetanus toxins prevents

A

release of inhibitory GABA

124
Q

effects of tetanus toxins

A

uncontrolled muscle spasms, lock jaw, death

125
Q

what is the main inhibitory neurotransmitter

A

GABA

126
Q

most common excitatory neurotransmitter

A

glutamate

127
Q

functions of glutamate

A

causes epsp

128
Q

20-day embryo structures

A

neural crest and neural plate

129
Q

neural crest

A

becomes the pns

130
Q

neural plate

A

plate of cells dividing to form regions, becomes the cns

131
Q

23-day embryo

A

pns and cons start to form

132
Q

what disease demyelinates neurons?

A

multiple sclerosis

133
Q

what causes MS

A
  • herpes
  • more in colder regions
  • epstein barr virus
  • genetic
  • environment
  • mono
134
Q

symptoms of MS

A
  • persona can’t conduct electrical signals
  • extreme fatigue
  • loss of vision
  • muscle cramps
  • difficulty walking

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