Exam 3 - Chapter 8 Flashcards
1
Q
ion
A
charged ion or molecules
2
Q
excitable
A
ability to be stimulated by electricity and conduct electricity via action potentials
3
Q
what types of tissue are excitable?
A
muscle and nervous tissue
4
Q
excitable cells
A
cells of excitable tissue that conduct electricity
5
Q
electrical potential
A
difference in charge between one point and another
6
Q
electrical potential is also called
A
voltage
7
Q
membrane potential
A
difference in charge across the plasma membrane
8
Q
membrane potential is also called
A
membrane voltage
9
Q
membrane potential =
A
cytoplasm voltage - ECF voltage
10
Q
electric current
A
flow of charge particles from one point to another
11
Q
gated ion channels
A
allow movement of ions in/out of the plasma membrane
12
Q
Resting membrane potential
A
difference in charge of cell cytoplasm compared to ECF when a cell is at rest
13
Q
neuron RMP
A
-70 mV
14
Q
muscle cell RMP
A
-90 mV
15
Q
k+
A
potassium ion
16
Q
k+ is highly concentrated in
A
the cytoplasm
17
Q
cytoplasmic anions
A
organic, negative ions that are bundles of proteins, phosphates, or nucleic acids
18
Q
cytoplasmic anions are/are not permeable to the plasma membrane
A
are not
19
Q
Na+
A
sodium ion
20
Q
Na+ is concentrated in
A
the ECF
21
Q
sodium-potassium pump allows ___ k+ into/out of the cell and ___ na+ into/out of the cell
A
2 K+ into cell, 3 Na+ out of cell
22
Q
sodium-potassium pumps maintain a ____ potential inside the cell
A
negative potential
23
Q
stimulation of excitable cells results in
A
a change in membrane potential, making the cell positive
24
Q
two ways a neuron can be stimulated
A
other neurons at the synapse or stimuli
25
skeletal muscle cells are stimulated by
neurons
26
neurotransmitters
chemical signals released from neurons to stimulate other neurons or muscle fibers
27
neurosoma
cell body where most of the cytoplasm and the nucleus is located
28
dendrites
projections from the neurosoma that receive signals from other neurons
29
axon
single projection from the neurosoma that sends signals
30
axoplasma
cytoplasm of the axon
31
axolemma
plasma membrane of the axon
32
initial segment
short portion of the axon between the hillock and first myelin cell
33
axon hillock
start/border of the axon
34
trigger zone
the axon hillock and initial segment
35
at which part of a neuron does action potential begin
trigger zone
36
terminal arborization
network of branches at the distal end of the axon
37
axon terminal
slight swelling at the very distal end of terminal arborization containing vesicles of neurotransmitters
38
an ion channel is also called a
channel protein
39
ion channel allows ____ ion to flow ___ its gradient _____ of the cell
ion channel allows one ion to flow down its gradient in/out of the cell
40
gated channel must
be opened by a stimulus
41
voltage gated ion channel opens/closes by
changes to membrane potential
42
one action potential leads to
more action potentials farther down the cell
43
local potentials are also called
graded potentials
44
local potentials
change in membrane voltage occurring near the stimulate area
45
step one of local potential
stimulus opens sodium ion channel
46
in the first step of local potential, what channel is opened?
sodium ion channel
47
step two of local potential
depolarization
48
what happens in the depolarization of local potential
sodium ions enter cells, making the membrane potential less negative
49
in depolarization, the membrane potential becomes less positive/negative
less negative
50
step three of local potential
sodium ions form a current and flow to the trigger zone
51
step four of local potential
the local potential leads to action potentials
52
unique properties of local potentials
graded, decremental, reversible, can be excitatory or inhibitory
53
what does it mean that local potential is graded
magnitude of the potential depend on the stimulus strength, can be weak or strong
54
what does it mean that local potential is decremental
the local potential gets weaker the farther they get from the stimulus source
55
local potentials are _____ while action potentials are always _____
decremental, strong
56
what does it mean for a local potential to be reversible
once the stimulus is gone, the cell returns to its Resting Membrane Potential
57
What does it mean for a Local Potential to be excitatory
the LP depolarizes the membrane and help cause action potentials
58
when a local potential is excitatory, the membrane potential goes
up
59
what does it mean for a local potential to be inhibitory?
LP's hyperpolarize the membrane making it more negative by open Chloride channels, letting Cl- in making it harder to generate action potentials
60
when local potentials are inhibitory, what ion channel is opened
chlorine ion channel
61
in inhibitory local potentials, the membrane potential goes
down
62
the first action potential is located at
the trigger zone
63
why are axons the place where neuron action potentials start
only place where there are enough voltage-gated sodium-potassium channels
64
when generating a neuron action potential, the local potential must _____ to the membrane threshold to open the sodium ion channels
depolarize
65
threshold of action potential
required voltage to lead to a particular electrical response
66
threshold for action potential
-55 mV
67
step one of action potential
at resting membrane potential, sodium and potassium ion channels are closed
68
at RMP, ion channels are
closed
69
step two of action potential
depolarization to -55 mV occurs
70
as depolarization of action potential begins,
1) voltage-gated ____ channels ___
2) ____ rushes into the cell, starting ____
3) membrane potential becomes more ____
1) voltage-gated sodium channels open
2) sodium rushes into the cell, starting depolarization
3) membrane potential becomes more negative
71
step three of action potential
membrane voltage reaches peak
72
peak of membrane voltage in action potential
+ 35 mV
73
as the membrane voltage peaks
1) Sodium ion channels ___
2) voltage-gated ___ channels ____
3) ____ rushes out of the cell
4) _____ begins
1) Sodium ion channels inactivate
2) voltage-gated potassium channels open
3) Potassium rushes out of the cell
4) repolarization begins
74
what does it mean for an ion channel to be inactivated
remains open, but a gate is closed
75
step four of action potential
membrane repolarizes to -70 mV
76
hyperpolarization
membrane voltage drops below -70 mV
77
in membrane repolarization
1) voltage gated ____ channels opens/closes slowly
2) ____ ion leakage channels let in enough of the ion to restore RMP to -70 mV
1) potassium
2) sodium
78
because voltage-gated potassium channels close slowly, enough potassium leave/enter the cell, causing brief
potassium leaves the cell, causing brief hyperpolarization
79
action potential is all or none, meaning
not graded, always reaches maximum voltage
80
action potential is non-decremental, meaning
it doesn't weaken with distance and triggers another AP
81
action potential is reversible/irreversible
irreversible
82
action potential is only excitatory, meaning
there is a dramatic depolarization followed by slight hyperpolarization
83
refractory period
period of resistance to a stimulation
84
the refractory period occurs
during the action potential and shortly after
85
absolute refractory period
during depolarization and repolarization
86
why is the absolute refractory period a thing
the sodium channels are open or inactivated, preventing a stimulus from causing the next action potential
87
relative refractory period occurs during
hyperpolarization
88
the relative refractory period can occur with
a strong stimulus
89
signal conduction
one action potential triggers another action potential downstream
90
signal conduction generates a
nerve signal
91
nerve signal
series of action potentials traveling down the axon
92
"downstream" a neuron
further distal from the soma and closer to the axon terminal
93
how does a nerve signal occur
the sodium ions that enter the cell during depolarization diffuse, causing voltage farther down the axon to reach the threshold and open more sodium gated ion channels
94
Are action potentials triggered in proximal axon segments
no, proximal segments are in absolute refractory period
95
saltatory conduction
"jumping" action potentials down stream
96
saltatory conduction occurs on
myelinated axons
97
continuous conduction
every segment of the axon participates in action potential
98
continuous conduction occurs when each segment has
sodium and potassium ion channels
99
continuous conduction occurs on
unmyelinated axons
100
synapse
junction between an axon terminal and the target cell
101
a target cell can be
a neuron or muscle cell
102
action potentials trigger what at the axon terminal
the release of neurotransmitters
103
presynaptic neuron
the neuron from which the signal comes and releases neurotransmitters
104
postsynaptic neuron
the neuron to which the signal goes and receives neurotransmitters
105
a post-synaptic neuron at one synapse can be
a pre-synaptic neuron at another
106
neuromuscular junction
the synapse between a neuron and muscular fiber
107
in a neuromuscular junction, the neuron is ___synaptic and the muscle fiber is ___synaptic
the neuron is presynaptic and the muscle fiber is postsynaptic
108
axon-dendrite synapse
between an axon and a dendrite
109
axosomatic synapse
between an axon and neurosoma
110
axoaxonic synapse
between two axons
111
the most common type of synapse is
axodendrite synapse
112
neurons can synapse with many or only one post-synaptic neuron
many
113
synaptic transmission
the transfer of a nerve signal from a presynaptic neuron to a target cell
114
excitatory cholinergic synapse
ACh is released from the presynaptic neuron and causes more action potentials in the postsynaptic neuron
115
excitatory cholinergic pre-synaptic neuron steps
nerve signal arrive at the axon, opening a voltage-gated calcium ion and release ACh into the synaptic cleft
116
excitatory cholinergic synaptic cleft steps
ACh diffuses across the clef and binds to the receptors on the postsynaptic nerve
117
synaptic cleft
space between cells
118
excitatory cholinergic post-synaptic neuron steps
ACh receptors open ion channels for sodium ions to enter and potassium to leave, depolarizing local potential and triggering an action potential
119
when nerve signals stop arriving at the presynaptic neuron
the axon terminal stops releasing neurotransmitters
120
when neurotransmitters stop releasing from the axon terminal
neurotransmitters are broken down by AChE after being released from receptors or diffuse into the ECF
121
reuptake
axon terminal reabsorbs the broken-down neurotransmitters via endocytosis
