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
2
Q
does membrane potential occur in all human and plant cells
A
yes
3
Q
how is membrane potential measured
A
millivolts (mV)
4
Q
example of excitable cells
A
nerve and muscle cells
5
Q
when do nerves and muscles rest?
A
during sleep, but continue to make or reserve atp
6
Q
nerve and muscle cell ability
A
can produce rapid, transit changes in their membrane potential when excited
7
Q
Resting membrane potential def
A
constant membrane potential present in cells of non-excitable tissues
8
Q
what mV does resting potential rest at
A
-70mV
9
Q
effects of Na-K pump in membrane potential
A
-contributes by its unequal transports of positive ions (3 Na and 2 K)
10
Q
what restores mp and how
A
Na-K pump using a carrier and ATP
11
Q
how is concentration measured?
A
millimoles/liters (mM/L)
12
Q
concentration of Na+ in ecf
A
150mM/L
13
Q
concentration of Na+ in icf
A
15mM/L
14
Q
relative permeability of Na+
A
1
15
Q
concentration of K+ in ecf
A
5mM/L
16
Q
concentration of K+ in icf
A
150mM/L
17
Q
relative permeability of K+
A
50-75
18
Q
what ions are involved in the production of membrane potential?
A
Na+ and K+
19
Q
what ions are present but not involved with mp
A
A- (carbohydrates, amino acids, proteins)
Cl-
HCO3-
20
Q
what ion is the first to take charge in creating an electrical signal?
A
Na+
21
Q
what ion is the most permeable/ leaky
A
K+
22
Q
what ion creates the opposite concentration gradient?
A
K+
23
Q
A- concentration in icf
A
65mM/L
24
Q
Cl- concentration in ecf
A
100mM/L
25
what ion moves around but doesn't create an electrical potential
Cl- and HCO3-
26
HCO3- concentration in ECF
30mM/L
27
excitable cells meaning
cells that change their resting potential to produce electrical signals when excited
28
Polarization
any state when mp is anywhere but at 0mV
| staying at -70mV/ being negative
29
depolarization
- less polarized (less negative) than at rp
| - moving towards 0mV after a stimulus has reached the threshold
30
repolarization
- membrane returns to rp (-70mV)
| - becoming negative
31
hyperpolarization
- membrane becomes more polarized than rp
| - more negative
32
what is the mV at hyperpolarization
below -70mV and can go down to -90mV
33
upward deflection =
decrease in potential (icf is less - )
34
downward deflection =
increase in potential (icf is more - )
35
what creates electrical signals
channels (many diff kinds)
36
voltage-gated channels
- electrical current will open them
- at rest = gate is closed
- excited = gate is open
37
what determines when voltage-gated channels open/close?
changes in membrane potential
38
chemically gated channels
open under command of chemical signals
| ~ neurocrines, paracrines, hormones
39
mechanically gated channels
- respond to stretching or mechanical deformation
| - need pressure or touch to open
40
thermally gated channels
- respond to changes in temp
41
what restores resting potential?
NA-K pump
42
what are the two kinds of potential changes?
graded potential
| action potential
43
where do graded potentials occur?
small, specialized region of the membrane
44
what type of change occurs with graded potential?
-small changes in membrane potential/ electrical state
45
how does graded potential progress?
dies down
46
which potential change goes in both directions?
graded potential
47
how to produce an electrical signal
-stimulus occurs, reaches threshold, depolarization ocurs
48
what do the magnitude and duration depend on in graded potential?
-strength and duration of triggering event (aka stimulus)
49
what happens with a stronger triggering event
more gated channels = more Na/ + charges in = depolarization
50
why does the potential in graded potential die down?
- K+ leaking out
| - cytoplasm = bad conductor `
51
current def
any flow of electrical chargers, current follows direction of + charges
52
examples of graded potential
- postsynaptic
- receptor
- end-plate
- pacemakers
53
where does end plate graded potential occur?
- occurs in neuromuscular junction
| between neuron and muscle
54
pace maker graded potential meaning
-set/make their own pace
55
where is a pacemaker graded potential found?
muscles
56
Action Potential location in neruon
cell membrane
57
ap time
brief, large, rapid
58
what is the magnitude of change in AP?
100mV
59
Action Potential description
- doesnt decrease in strength
| - long-distance signals
60
what potential is involved with positive feedback
action potential
61
rising phase cause
Na+ influx which causes depolarization
62
peak meaning
+30 mv is reaching, K+ efflux begins
63
falling phase cause
- K+ efflux, repolarization occurs
64
threshold potential
- triggered by an increase in Na+ permeability
- minimum stimulus require to go beyond
- rests at -50mV
65
activation gate structure
latch like
66
inactivation gate structure
ball and chain
67
when does the inactivation gates begins to close?
at peak
68
undiminished movement
ensures ap will cover the entire membrane
69
what ensures undiminished movement?
refractory period
70
refractory period
- period of time followed by an ap
- marked by decreased excitabtily
- another ap will not occur
71
absolute period
- ap is occurring in present time, so another one cant occur
- all of depolarization and most of repolarization
- Na gates are closed
72
Relative period
- last part of repolarization and hyperpolarization
- Na+ gates closed, some K are open
- resting phase
73
can another ap occur during the relative period
yes, if the stimulus is urgent or stronger than the first
74
consequences of refractory period
- all or none principle
| - undirectional
75
movement of ap propagates from ___ to ___
axon hillock to axon terminal
76
collaterals
side branches of axon
77
input zone
signals are received
78
dendrite/ dendrite zone
gather stimulus
79
cell body
contains nucleus
80
trigger zone location
axon hillock
81
trigger zone function
ap is initiated
82
conducting zone location
axon
83
conducting zone function
conducts ap in undiminishing fashion
84
output zone location
axon terminal
85
output zone structure
releases a neurotransmitter that influences other cell
86
how does conduction/ap propagate through nerve cells?
contigous conductions and saltatory conduction
87
contigous conduction location
in unmyelinated neurons
88
contigous conduction process
ap spreads along every portion of membrane
89
speed of contigous conduction
0.7m/s in digestive system neurons
90
energy consumption of saltatory conduction
conserves energy, since channels dont have to reset
91
how to increase speed of ap
- large diameter
| - myelination (50x faster)
92
myelin function
- used to insulate
| - makes saltatory conduction possible
93
what is myelin composed of?
lipids
94
which cell forms myelin in the CNS?
oligodendrocytes
95
where are Schwann cells found + function
PNS and make myelin
96
synapses
junction between 2 neurons
97
synaptic cleft
area between neurons
98
presynaptic neuron
takes message toward synapse
99
postsynaptic neuron
-takes message away from synapse
100
synaptic vesicle
-stores neurotransmitters
101
synaptic knob
- contains synaptic vesicles
| - touches postsynaptic neuron
102
does contignous conduction use atp?
yes, cuz membrane resets each time
103
saltatory conduction location
in myelinated fibers
104
saltatory conduction propagation process
-impulses jump over sections of the fibers covered with insulating myelin
105
which conduction is faster
saltatory conduction, it is 120m/s in muscle cell
106
types of synapse
excitatory and inhibitory
107
excitatory synapse function
creates small depolarization
108
inhibitory synapse function
leads to small hyperpolarization
109
what does more negative membrane potential mean
harder to make ni
110
neural summation definiton
effect of 2 different potentials (inhibitory or excitatory) coming together
111
what does neural summation create
grand postsynaptic potential
112
what does grand postsynaptic potential include
temporal or spacial summation
113
what dictates grand postsynaptic potential
rates of presynaptic neutrons firing
114
temporal summation
several epsp occurring very close in time
115
epsp
excitatory postsynaptic potential
116
ipsp
inhibitory postsynaptic potential
117
grand postsynaptic potential depends on
sum of activity in all presynaptic inputs and determines if a neuron will undergo ap
118
spacial summation
-2 different excitatory or inhibitory add up in a space, 2 diff inputs from diff areas in one space
119
cancellation of ipsp and epsp occurs
-inhibitory and excitatory signal cancel each other
120
what is missing in Parkinson's
dopamine in bASal gangli
121
result of Parkinson's
muscular rigidity + involuntary tremors
122
cocaine use causes too much off..
dopamine in the brain
123
tetanus toxins prevents
release of inhibitory GABA
124
effects of tetanus toxins
uncontrolled muscle spasms, lock jaw, death
125
what is the main inhibitory neurotransmitter
GABA
126
most common excitatory neurotransmitter
glutamate
127
functions of glutamate
causes epsp
128
20-day embryo structures
neural crest and neural plate
129
neural crest
becomes the pns
130
neural plate
plate of cells dividing to form regions, becomes the cns
131
23-day embryo
pns and cons start to form
132
what disease demyelinates neurons?
multiple sclerosis
133
what causes MS
- herpes
- more in colder regions
- epstein barr virus
- genetic
- environment
- mono
134
symptoms of MS
- persona can't conduct electrical signals
- extreme fatigue
- loss of vision
- muscle cramps
- difficulty walking
