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MCAT Biology > NS > Flashcards

NS Flashcards

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1
Q

nucleus of neuron is in…

A

soma

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2
Q

soma is the location of which two organelles?

A

ER and ribosomes

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3
Q

dendrites

A

appendages emanating directly from the soma receiving incoming messages from other cells

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4
Q

axons hillock

A
  • receives information sent from dendrites through soma and integrates incoming signals
  • summation of the inhibitory and/or excitatory signals from dendrites until threshold is reached initiating an AP
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5
Q

axon

A

myelin sheath wraps around axon and APs are conducted through this structure until reaching the axon terminal

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6
Q

myelin

A

fatty membrane preventing signal loss or crossing of signals

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7
Q

myelin sheath

A

maintain electrical signal within one neuron, inc conduction speed

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8
Q

In CNS myelin is produced by…

A

oligodendrocytes

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9
Q

In PNS myelin is produced by…

A

Schwann cells

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10
Q

nodes of Ranvier

A

gaps between sheath

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11
Q

nerve terminal

A

flat and large to maximize signal transmission and release of NTs to move through synaptic cleft and bind to dendrites of postsynaptic neuron

(nerve terminal, synaptic cleft, and postsynaptic membrane ~> synapse)

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12
Q

nerve

A

multiple neurons bunbled together in PNS

can be sensory, motor, or mixed

cell bodies of neurons of the same type are clustered together into ganglia

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13
Q

tracts

A

axons bundled together in CNS

only carry one type of info

cell bodies of tract are grouped into nuclei

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14
Q

glial cells

A

cells that support and myelinate neurons

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15
Q

astrocyte

A
  • form BBB (controls transmission of solutes from bloodstream into nervous tissue)
  • nourish neurons
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16
Q

ependymal cells

A
  • line ventricles of brain and produce cerebrospinal fluid
  • physically supports brain and acts as a shock absorber
17
Q

microglia

A

phagocytic cells that ingest and break down waste products and pathogens in CNS

18
Q

oligodendrocyte (CNS) and Schwann cell (PNS)

A

produce myelin around axons

19
Q

neuronal resting potential

A

~ -70 mV (inside neurons relatively neg)

K+ 140 mM inside 4mM outside hence potassium leak channels
BUT
equilibrium potential of ~ -90 mV (moving out)

Na+ 12 mM inside 145 mM outside hence sodium leak channels
BUT
equilibrium potential of ~ 60 mV (moving in)

20
Q

threshold value

A

~ -55 mV to -40 mV

21
Q

excitatory input causes

A

depolarization

22
Q

inhibitory input causes

A

hyperpolarization

23
Q

what are the two types of summation?

A

temporal and spatial

24
Q

temporal summation

A
  • multiple signals integrated during a relatively short period of time
25
Q

spatial summation

A
  • the additive effects are based on the number and location of the incoming signals
26
Q

sodium channel behavior during AP

A
  • closed before ~ -55 to -40 mV
  • open from threshold to +35 mV
  • inactive +35 mV to resting potential
27
Q

the effluent of K+ causes…

A
  • overshoot of resting membrane potential
  • hyperpolarization of the neuron
  • absolute vs relative refractory periods
  • resting potential restored by Na+/K+ ATPase
28
Q

impulse propagation

A
  • as sodium rushes into one segment of the axon, it will cause depolarization in the surrounding regions
  • sodium channels of other segments then open and action potential propagated like a wave through the axon and each segment that it’s passed through becomes momentarily refractory
  • speed of impulse propagation depends on length and cross sectional area of the axon (inc length means higher resistance and slower conduction, but inc cross sec area allows for faster propagation due to dec resistance and this effect is more powerful than length)
29
Q

saltatory conduction

A
  • membrane only permeable to ion movement at nodes of Ranvier bc of myelin insulation
  • signal hop node-to-node
30
Q

same type of neuron…

A

same potential diff

inc stimulus intensity means inc firing frequency NOT inc potential diff

31
Q

how does the calcium get into the presynaptic cell to release the NT?

A

voltage-gated Ca channels open

32
Q

postsynaptic receptor types

A
  • G-coupled: either levels of cAMP altered or influx of calcium
  • ligand-gated ion channels: depolarization or hyperpolarization upon binding
33
Q

how can NT be removed from cleft

A

1) enzyme (acetylcholinesterase)
2) reuptake (5-HT, DA, NE)
3) diffuse out (nitric oxide)

34
Q

the brain consists of…

A

white matter ~> axons encased in myelin sheaths (lies deeper than grey matter)

grey matter ~> unmyelinated cell bodies and dendrites

35
Q

cell bodies of sensory neurons can be found in…

A

DRG

36
Q

parasympathetic NS main NT

A

acetylcholine

released by both pre and postganglionic neurons

37
Q

sympathetic NS main NTs

A

preganglionic neurons release ACh and post release NE

38
Q

monosynaptic reflex arc

A

single synapse between sensory neuron and motor neuron

knee jerk: patellar tendon stretched, info travels up sensory neuron, synapses onto motor neuron, which causes contraction of quad

39
Q

polysynaptic reflex arc

A

at least one interneuron between sensory and motor

withdrawal reflex

MCAT Biology (13 decks)

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