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anp 1105 > neurotrasnmission and propgation > Flashcards

neurotrasnmission and propgation Flashcards

1
Q

what are the 4 functional regions

A

1) receptive region (cell body and dendrites)
2) inital segment (axon hillocks)
3) conductive region (axon)
4) secretory region (nerve terminals)

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2
Q

what do nerve terminals do?

A

pack neurotransmitters. calcium will drive and plasma membrane will attach to each other.

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3
Q

Why are dendrite branch’s so long

A

to get the electrical signal from other neurons synaptic terminals

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4
Q

where is the region capable of initial axon potential

A

axon hillocks

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5
Q

how are changes in membranes potential produced

A

1)anything that
alters ion concentrations on the two sides of the membrane, or (2) anything that changes
membrane permeability to any ion.

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6
Q

what are graded potentials

A

Graded potentials-usually incoming signals operating over short distances that have variable (graded) strength

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7
Q

what are action potentials

A

long-distance signals of axons that always have the same strength

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8
Q

what’s the difference between depolarization and hyper polarization?

A

depolarization is MP moving closer to 0 mV, hyperpolarization is becoming more negative.

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9
Q

what is -70 mV to -65 mV? -70 mV to -75 mV?

A

depolarization. hyperpolarization

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10
Q

what happens if an axon is long?

A

it will not travel that far because current flow decreases in magnitude with distance

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11
Q
  1. What determines the size of a graded potential?
A

the strength of the stimulus.

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12
Q

what is the difference between action potential and gradient potential

A

-action potential is one direction ​

-gradient potential is bidirection

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13
Q

what is the presynaptic neuron

A

neuron conducting impulses toward synapse (sends information)​

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14
Q

what is the Postsynaptic neuron

A

neuron transmitting electrical signal away from synapse (receives information)

  • In PNS may be a neuron, muscle cell, or gland cell​
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15
Q

what receptors cause rapid synaptic transmission

A

channel-linked receptors

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16
Q

action potential go from -90mV to +50mv with a 140mV. T or F?

A

False. total amplitude (change in voltage) of about 100 mV (from -70 mV to +30 mV)

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17
Q

what is another name for an action potential

A

nerve impulse

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18
Q

what do stimulus do to the membrane?

A

change the permeability

19
Q

what is the action potential membrane steps

A
  1. resting state (no ions move through voltage gate channels -70mV)
    2.Depolarization cause by Na flowing into cell
  2. repolarization caused by k flowing out of the cell
  3. hyperpolarization cause by k+ continually flowing out of the cell
20
Q

what is the threshold for AP? what is the Peak?

A

-55mV

+30

21
Q

how can you tell the difference between how strong stimulus strength is from a weak one or a strong one?

A

Strong stimuli generate nerve impulses more often in a given time interval than do
weak stimuli.

22
Q

when is the absolute refractory period?

A

with opening of na+ channels and ends with na+ channels beginning to reset to original resting state

23
Q

what increases the speed of propgation

A

mylin sheaths

24
Q

what is a synapse?

A

syn “to clasp or to join” connection of one neuron to another

25
Q

what is a presynaptic neuron?

A

neuron conducting impulses toward the synapse

26
Q

what is postsynaptic neuron?

A

neuron transmitting signal away from synapse

27
Q

What is anterograde transport?

A

movement of supplies down the axon away from soma (cytoskeleton, membrane parts)

28
Q

What is retrograde transport?

A

movement up the axon toward the soma (recycled and degraded organelles)

29
Q

what is MS

A
  • persistent inflammatory response in which myelin sheaths gradually destroyed
    -cycles of relapse and remission: flare-ups and then some healing and myelin regeneration; axons develop more Na+ channels in demyelinated areas
    -blindness (optic nerve), muscle weakness, clumsiness, urinary incontinence​
    -ultimately myelin destruction is permanent and axons “drop out” or degenerate​
30
Q

what are types of therapy for MS

A

1) reduce inflammatory destruction​

(2) manage symptoms​

(3) promote repair of damaged myelin​

31
Q

how many axon terminals do neurons have

A

1,000 - 10,000

32
Q

what is the post synaptic cell outside of the CNS

A

effector cell (muscles cell or gland cell)

33
Q

what is the synapses between an axon and dendrite of another neuron called?

A

axodendritic synapses

34
Q

what is between axon endings of one neuron and the cell body (soma) of another neuron called?

A

axosomatic synapses

35
Q

what is electrical synapses?

A

direct physical contact between cells with a gap junction

-uncommon

-direct current flow through protein channels

-rapid transmission (electrically-coupled)​

neurons can be synchronized​

-primarily embryonic, eye movement, non nervous tissues like cardiac or smooth muscle where contractions can synchronize

36
Q

3 ways to terminate neurotransmitter

A

-Reuptake by astrocytes or the presynaptic terminal,
where the neurotransmitter is stored or destroyed by
enzymes (as with the neurotransmitter norepinephrine)
* Degradation by enzymes associated with the postsynaptic membrane or present in the synaptic cleft (as with
acetylcholine)
* Diffusion away from the synapse (nitric oxide)

37
Q

what is chemical synapse

A

-slow
-abundant
-effectively convert electrical to chemical to electrical

38
Q

what are the steps for chemical synapse?

A

1)Action potential
arrives at axon terminal

2)Voltage-gated ca2 channels
open and ca2 enters the axon
terminal.

3)Ca 2 entry causes
synaptic vesicles to
release neurotransmitter
by exocytosis.

4)Neurotransmitter diffuses
across the synaptic cleft and
binds to specific receptors on
the postsynaptic membrane

5)Binding of neurotransmitter opens ion channels,
resulting in graded potentials.

6) Neurotransmitter effects are terminated
by reuptake through transport proteins,
enzymatic degradation, or diffusion away
from the synapse

39
Q

why is a synaptic transmission unidrectional

A

it can only be produce down the axon not the dendrites

40
Q

what are the proteins in the gap junction?

A

connexins

41
Q

Mechanism of Synaptic Communication​

Initiation:​

A
  1. Ca++ gates open in presynaptic terminal​
  2. Neurotransmitter release​
  3. Neurotransmitter binds to postsynaptic receptors​
  4. Ion channels open in postsynaptic membranes
42
Q

summations of postsynaptic neurons

A

no summation (EPSP’s dont add)
temporal summation: close in time (EPSP’s add together)
spatial summations: 2 different stimuli in 2 diff locations add together
spatial summation of EPSPs and IPSP’s (cancel each other out)

43
Q

What do we mean when we say that an area of a neuron is refractory to further stimulation?

A

at point in time where the nerve cannot be stimulated repeatedly

anp 1105 (20 decks)

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