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Physiology > Nervous system > Flashcards

Nervous system Flashcards

1
Q

What does a typical neuron have

A

some, one axon, one or more dendrites

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2
Q

what does the soma contatin

A

nucleus, er, golgi and ribosomes

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3
Q

what is the axon hillock

A

part of axon, typically where integration of the input is completed and the action potential is generated

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4
Q

how does the axon conduct information away from the soma

A

action potential

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5
Q

what is at the end of the axon branch

A

presynaptic terminals

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6
Q

what are the function of a neuron

A

input, integration, conduction, out, maintenance

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7
Q

Input

A

incoming synapses. can come into any part of neuron

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8
Q

integration

A

accomplished in dendrites and soma

-resulting info reaches axon hillock, decision about what info to conduct down axon is completed

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9
Q

conduction

A

information must be carried from the soma to the presynaptic terminals

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10
Q

output

A

usually in form of chemical synapse

-could also be paracrine, endocrine, or electrical synapse

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11
Q

maintenance

A

membranes and proteins used to process info must be replaced with new ones

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12
Q

kinesin

A

motor protein that drags vesicle of new membrane down the axon in an anterograde direction

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13
Q

dynein

A

motor protein that drags vesicle of old membrane down the axon in a retrograde direction

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14
Q

calculating equilibrium potentials

A

E-ion=60mV/(ion charge)log*(ion out)/(ion in)

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15
Q

what is equilibrium potential

A

when flow of ion out of cell due to concentration equals the flow into cell because of voltage

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16
Q

potassium voltage

A

flows out of cell because of concentration, flows back in because that makes the voltage in the cell negative and it attracts the positively charged K+

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17
Q

how the closing of channels determines flow of ions and membrane potential change

A
  • if channels open, membrane potential goes towards the equilibrium potential for that ion
  • if channels close, membrane potential goes away from the equilibrium potential for that ion
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18
Q

what determines the membrane potential of the cell

A

the concentration gradients and permeabilities of each ion

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19
Q

what is the membrane potential closest to at any given time

A

closest to equilibrium potential of the ion with the greatest permeability

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20
Q

what is the cell at when resting

A

K+ channels open, so the cell is near Ek, some negative membrane potential
-average is -70mV

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21
Q

hyperpolarization

A

changes that make the membrane potential more negative

22
Q

depolarization

A

changes that make the membrane potential more positive

23
Q

graded potentials

A

caused by inputs to the neuron

  • can be on any amplitude
  • spread across the membrane and decrease in strength the further from origin they are
24
Q

action potentials

A

triggered by graded potentials

  • all or nothing
  • happen fast
  • conduct down an axon
  • have a refractory period
  • time after one spike when another one either cannot occur (absolute) or has a higher than normal threshold (relative)
25
Q

two different kinds of voltage gated channels that influence action potentials

A

voltage gated Na+

voltage gated K+

26
Q

voltage gated Na+ channels

A
  • active when they are depolarized because the gate is positively charged, and is pushed outwards as the inside of the cell becomes positive
  • very fast
  • causes positive feedback loop, continues depolarization
  • Na+ gradient makes Na+ flow inwards
  • inactivation occurs when the inactive gate closes as a result of depolarization
  • slower gate, happens after active gate
27
Q

Voltage-gated K+ channels

A
  • active when the are depolarized because the voltage gate is positively charged, and it is pushed outwards as the inside of the cell becomes positive
  • activate slowly
  • K+ gradient makes K+ diffuse outward, so repolarizes/hyperpolarizes cell
  • do not inactivate, cause hyperpolarization, close when membrane potential is below threshold
28
Q

what is an action potential in terms of channels

A

sequential opening and closing of ion channels

  • membrane potential will be closest to the equilibrium potential of the ion with the most open channels
  • opening a channel causes Vm to move towards Eion and closinga channel causes Vm to move away from Eion
29
Q

what happens at the peak of an action potential

A

greatest number of open Na+ channels, Vm close to Ena

30
Q

what impacts how far current will travel in an axon

A

the larger the axons diameter, the more current will flow and the easier it will flow

  • larger conduction velocity
  • if membrane resistance is high (more difficult for the current to leave the axon). that’s why there’s myelination
31
Q

nodes of ranvier

A

myelinated axon spaces where voltage gated Na+ and K+ channels are located. Action potential “jumps” from node to node

32
Q

chemical synapse

A

an AP in axon depolarizes presynaptic terminal

  • voltage gated Ca++ channels open near active zones
  • increased cytoplasmic Ca++ causes exocytosis of neurotransmitter
  • neurotransmitter diffuses across synaptic cleft
  • NT receptors in postsynaptic cell respond
33
Q

what does Ca++ do in the presynaptic terminal

A

the ca++ binding proteins in synaptic vesicle membrane cause membrane fusion in response to Ca++ (no calmodulin)

34
Q

quantum

A

the entire content of each synaptic vesicle being released during exocytosis

35
Q

how is ca++ removed

A

ca++-atpase pumps

36
Q

where are the receptors for NT located

A

in the subsynaptic (post) membrane because NT is water soluble, not lipid soluble

37
Q

things that affect the response of target cell

A
  1. number of receptors
  2. affinity of receptor
  3. concentration of neurotransmitter
  4. type of receptor present
38
Q

EPSP

A
  • voltage change in post-synaptic cell that causes the cell to be more likely to fire action potentials or causes it to release more neurotransmitter
  • excitatory post-synaptic potential
39
Q

IPSP

A
  • inhibitory post-synaptic potential
  • voltage change in post-synaptic cell that causes the cell to be less likely to fire action potentials or release neurotransmitter
40
Q

the 8 h2o soluble neurotransmitters

A
  • amino acids: glutamate, glycine, GABA
  • monoamines
  • -catecholamines (made from tyrosine): dopamine, epinephrine, norepinephrine
  • made from tryptophan: seratonin
  • made from histidine: histamine
  • acetylcholine (monoamine)
41
Q

type of synapse for acetylcholine

A

cholinergic

42
Q

type of synapse for nor/epinephrine

A

adrenergic

43
Q

temporal summation

A

summation of PSP that arrive at different times

-quick firings from one synapse to reach AP

44
Q

spatial summation

A

summation of PSP that arrive at different synapses

45
Q

amplitude coding

A

level of excitation in the soma is encoded by amplitude of the graded potentials
-represents summation of various PSP

46
Q

frequency coding

A

translation of amplitude coding

  • coding of action potentials at axon hillock
  • frequency of action potentials increases as the amplitude of the graded potential increases
47
Q

what do somatic motor nerves use as a neurotransmitter

A

acetylcholine

-called a cholinergic synapse

48
Q

what are preganglionic and postganglionic synapses called in parasympathetic

A

cholinergic-use acetylcholine

49
Q

what are postganglionic synapses called in the sympathetic system

A

adrenergic because they use norepinephrine

-preganglionic fibers are cholinergic

50
Q

varicosities of axons

A

release neurotransmitter into tissue of organ, resemble paracrine secretion

Physiology (11 decks)

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