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A&P 223 > Exam #3 Chapter 11- part 2 > Flashcards

Exam #3 Chapter 11- part 2 Flashcards

(102 cards)

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1
Q

what are action potentials caused by?

A

graded potentials

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2
Q

what causes ion differences?

A

the membrane

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3
Q

what does neuron and muscles cells use the ion differences to produce?

A

action potential

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4
Q

what do graded potentials go up and down from?

A

diffusion across the membrane

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5
Q

what will happen if certain molecules bind to ligand-gated sodium channels?

A

it will produce a depolarization (graded potential)

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6
Q

what happens if graded potentials summat to (or past) the threshold in the initial segment?

A

an action potential will occur in the initial segment (all-or-none principle)

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7
Q

what can graded potentials do before diffusing away?

A

persist for a while

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8
Q

what is the difference in length of action and graded potentials?

A

graded potentials are long, action potentials are only 1-2 milliseconds long and a graded potential can be added together

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9
Q

where do action potentials occur?

A

in the initial segment in the axon

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10
Q

where do graded potential occur?

A

cell bodies and dendrites but can diffuse far enough that they reach the initial segment (axon)

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11
Q

what is an action potential for the membrane?

A

a quick change

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12
Q

what is a depolarization phase followed by?

A

a repolarization phase and afterpotential

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13
Q

what is the depolarization phase?

A

when the membrane potential moves away from the resting state and becomes more positive

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14
Q

what is the afterpotential?

A

when the plasma membrane becomes hyperpolarized after repolarization

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15
Q

what is the repolarization phase?

A

when the membrane potential returns toward the resting state and becomes more negative

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16
Q

what encourages action potentials?

A

graded depolarizations

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17
Q

what discourages action potentials?

A

graded hyperpolarizations

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18
Q

what will a graded depolarization to or past the threshold do?

A

open voltage-regulated sodium channels producing the depolarization and action potential

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19
Q

what do voltage-regulated sodium channels have?

A

two gates operated independently

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20
Q

what are the three possibilities for the voltage-regulated sodium channels?

A

1) closed but CAN open (inactivation gate open and activation gate closed)
2) open- (both gates open)
3) closed and CANNOT open (inactivation gate closed and activation gate open)

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21
Q

what does a graded potential do to the membrane?

A

depolarizes it to the threshold

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22
Q

what are the gates when a graded potential is below the threshold?

A

sodium channels are closed but can open

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23
Q

what are the gates when a graded potential is at the threshold?

A

the sodium channels are open

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24
Q

what are the gates when a graded potential is at +30mV?

A

the sodium inactivation gates close and voltage-gated potassium channels open producing the repolarization

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25
what are the gates when a graded potential is in repolarization?
the sodium-voltage gated channel activation gates close and then the inactivation gates open
26
what happens to the potassium voltage-regulated channels when at -70mV
they close
27
what dose the closing of the potassium regulated channels when at -70mV allow for?
the membrane polarization to exceed -70mV (afterpotential)
28
after the afterpotential of the potassium voltage regulated channel exceeding -70mV what occurs?
the membrane potential returns to -70mV
29
what happens to the small amount of sodium ions that came into the potassium voltage channel?
it is quickly pumped out
30
where does the all-or-none principle occur?
in the initial segment
31
what needs to occur in order for an action potential to occur?
needs to reach the threshold
32
between the time that the sodium channels open until the sodium channels are returned to configuration before a depolarization what occurs?
the initial segment will NOT respond to any graded potential to generate another action potential (absolute refractory period)
33
between the return of the sodium channels to the configuration before depolarization until the return to the resting membrane potential what occurs?
another action potential can be generated by a larger stimulus than the original one (relative refractory period)
34
what will a larger stimulus past the threshold generate?
a series of action potential (up to a limit) and higher frequency of action potentials is interpreted as a stronger signal
35
what do action potentials propagate from?
the initial segment to the axon terminals
36
`what will happen with an unmyelinated axon?
the depolarization of one section during the depolarization phase will depolarize the next section to the threshold.
37
what will happen with a myelinated axon?
the depolarization of one node depolarizes the next node to the threshold, propagating the action potential down the axon in saltatory conduction
38
what influences the propagation speed of action potentials? (3) (PTD)
1) the presence of myelin 2) the thickness of myelin 3) the diameter of the axon
39
what are the characteristics of type A fibers? (3) (TLF)
1) thick myelin 2) large axon 3) fastest
40
what are the characteristics of type B fibers? (3) (TMS)
1) thin myelin 2) medium axon) 3) slower than Type A but faster than Type C
41
what are the characteristics of type C fibers? (3) (NTS)
1) no myelin 2) thin axon 3) slowest
42
what happens at the synapse?
information from one neuron (the presynaptic cell) is transmitted to another neuron or an effector cell (postsynaptic cell)
43
how many synapses does the average neuron have?
about 5000
44
how many synapses do certain neurons have in the cerebellum?
up to 200,000
45
are electrical synapses rare or common?
rare
46
how are cells connected in electrical synapses?
by gap junction
47
in electrical synapses what is an action potential in the presynaptic cell aways generate ?
an action potential in the postsynaptic cell (2 cells behave as one making it fast)
48
what are the most common synapses between neurons?
chemical synapses
49
in chemical synapses what occurs to the action potential in the presynaptic cell?
it MAY generate an action potential in the postsynaptic cell (allows information processing) (slower)
50
in chemical synapses what is the presynaptic termainal separated from?
the postsynaptic membrane
51
what is the presynaptic terminal separated from the post synaptic membrane by in chemical synapses?
a synaptic cleft
52
what are synaptic clefts usually filled with?
synaptic vesicles containing a neurotransmitter
53
in chemical synapses when an action potential in the presynaptic axon opens what happens?
voltage-gated calcium channels and the calcium causes synaptic vesicles to fuse with the presynaptic axon membrane
54
what happens when synaptic vesicles fuse with the presynaptic axon membrane in chemical synapses?
the neurotransmitter is dumped into the synaptic cleft
55
after the neurotransmitter is dumped into the synaptic cleft in chemical synapses what does the neurotransmitter usually do?
bind to a ligand-gated ion channel that produces a graded depolarization or hyperpolarization
56
when neurotransmitters bind to ligand-gated channels in chemical synapses and produce a grade depolarization or hyperpolarization, what does that depend on?
the ion that crosses the membrane and receptor
57
what happens to neurotransmitter in chemical synapses?
either enzymatically degraded, taken up by the presynaptic terminal or diffuses out of the synapse
58
what are the neurotransmitters in chemical synapses usually?
ligand-gated channels to which only specific molecules can bind
59
what does the effect of a neurotransmitter in chemical synapses on a postynaptic membrane depend on?
the nature of the neurotransmimtter receptor and what ion crosses the membrane
60
what is an example that the neurotransmitter AcH would be used for?
myasthenia gravis
61
what is an example that the neurotransmitter serotonin would be used for?
antidepressant therapy and hallucinogens
62
what are some transitters that fall into the category of biogenic amines?
1) serotonin 2) dopamine 3) norepinephrine
63
what is an example that the neurotransmitter dopamine would be used for?
drug addiction and parkinson disease
64
what is an example that the neurotransmitter norepinephrine would be used for
ADHD and amphetamines
65
what neurotransmitters fall into the category of amino acids? (3) (GGG)
1) gamma-amino butyric acid (GABA) 2) Glycine 3) glutamate
66
what is an example that the neurotransmitter GABA would be used for? (3) (BBA)
1) barbiturates 2) benzodiazepines (anti-anxiety drugs) 3) alcohol dependence
67
what is an example that the neurotransmitter glycine would be used for?
strychnine poisoning
68
what is an example that the neurotransmitter glutamate would be used for?
stroke and excitotoxicity
69
what have many substances been identified as?
neurotransmittesr
70
what do some neurons release?
more than one neurotransmitter
71
what are neuromodulators?
neurotransmitters released by neurons that affect synaptic activity at distant synapses
72
what do some drugs affect?
synaptic activity
73
what do axoaxonic synapses do?
either reduce or increase the amount of neurotransmitters released
74
what is it called when axoaxonic synapses reduce the amount of neurotransmitters released?
presynaptic inhibition
75
what is it called when axoaxonic synapses increase the amount of neurotransmitters released?
presynaptic facilitation
76
what is a graded depolarization in a postsynaptic neuron called?
excitatory postsynaptic potential (EPSP)
77
what is true of EPSP?
the neuron is close to firing
78
what neurotransmitter falls into the category of purines?
adenosine
79
what is an example that the neurotransmit adenosine is used for?
neuroprotective agent and caffeine
80
what is a neurotransmitter that falls under the category neuropeptides?
endorphins
81
what is an example of what the neurotransmitter neuropeptides (endorphins) are used for?
pain therapy and opiates
82
what is a neurotransmitter that falls into the category of gases?
nitric oxide
83
what is an example that the neurotransmitter nitric oxide is used for?
stroke damage and treatment for erectile dysfunction
84
what is a graded hyperpolarization in a postsynaptic neuron called?
an inhibitory postsynaptic potential (IPSP)
85
what is true of IPSP?
the neurons is further from firing
86
is a single EPSP large enough to depolarize the initial segment to or past the threshold?
no
87
even though a single EPSP isn't large to depolarize the initial segment to or past the threshold what does it do?
persist for a period of time
88
what has to happen to ESPS and IPSP in order for an action potential to be produced?
the EPSP and IPSP are added together in time and the neuron does nothing until the membrane at the initial segment is depolarized to or past the theshold
89
what are two ways that EPSPs can be added together?
1) spatial summation | 2) temporal summation
90
where do EPSPs and IPSPs ocur?
on the dendrite
91
how does spatial summation occur?
by 2 or more neurons
92
how does temporal summation occur?
by one neuron
93
with thousands of neuron synapses on a neuron what are neural pathways?
complex
94
what type of pathways exist?
serial and parallel
95
what are some of the circuits that there are evidence of? (4) (CDRP)
1) convergent pathways 2) diverging pathways 3) reverberating circuits 4) parallel after-discharge circuits
96
what does convergent pathways allow?
IPSPs and EPSPs to affect an output. multiple neurons converge upon and synapse with a smaller number of neurons
97
what does diverging pathways do?
enlarge the effect of a signal
98
what does reverberating circuits do?
produce a series of action potentials
99
what does parallel after-discharge circuits have?
complex functions
100
what type of pathway does divergent pathways create?
parallel pathways
101
what does the reverberating circuit cause?
complete tetanus
102
what type of circuit is parellel-discharge circuit?
serial

A&P 223 (50 decks)

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