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Physiology Test 1 > 7 Synapses: CNS and NMJ > Flashcards

7 Synapses: CNS and NMJ Flashcards

1
Q

synapse def

A

point of contact between the terminals of one neuron and the target neuron

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2
Q

release of a chemical transmitter from the terminals of the presynaptic neuron occurs in response to ____ by an ____

A

depolarization by an AP

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3
Q

the _____ signal in the presynaptic nerve is converted into a ______ one in the postsynaptic nerve

A

electrical, chemical

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4
Q

quantum of transmitter is stored in

A

synaptic vesicles of the presynaptic nerve

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5
Q

vesicles are anchored at the

A

active zone

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6
Q

after the nerve is depolarized, this happens (4 steps)

A

voltage gated Ca2+ channels open in the active zone
Ca2+ enters near the vesicles
vesicle fusion and excytosis
release of transmitter (quantum)

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7
Q

probability that vesicles at CNS synapses will fuse and release is low and depends on (2 things)

A

1/ number of vesicles in active zone
2/ increase in Ca2+ ions in the vicinity of the vesicles (due to AP frequency - higher frequency leaves a little Ca2+ behind and it builds up)

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8
Q

Ca2+ ions are removed by (3 things)

A

1/ Na+/Ca2+ exchange (secondary active transport)
2/ primary active transport across the PM or into the SR (Ca2+ ATPase)
3/ uptake by mitochondria

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9
Q

transmitter action terminates when it gets too low. this happens by two mechanisms:

A

1/ reuptake

2/ breakdown of the transmitter

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10
Q

postsynaptic receptors bind ____

A

ligands (chemical signaling molecules)

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11
Q

agonist

A

a ligand that produces a response in the target cell when it binds to the receptor

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12
Q

antagonist

A

a ligand that binds to the receptor but does NOT produce a response

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13
Q

transducer

A

convert chemical signals into cellular responses (all receptors are this)

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14
Q

this is how the post synaptic receptor works

A
  • ligand (receptor) binds to the channel on the extracellular domain
  • ion channel opens
  • ions flow in, down their electrochemical gradient
  • transmitter dissociates from receptor and channel closes
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15
Q

post synaptic potential (PSP)

A
  • created by the ionic current that flows through open post synaptic channels
  • graded, localized
  • spreads passively
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16
Q

2 excitatory transmitters

A

acetylcholine

L-glutamate

17
Q

main excitatory transmitter in the CNS

A

L-glutamate

18
Q

excitatory transmitter at the NMJ

A

acetylcholine

19
Q

excitatory post synaptic potential (EPSP)

A

produced by an inward positive ion concentration

depolarization

20
Q

how many EPSPs must sum together to fire APs?

A

hundreds or thousands

21
Q

the NMJ is the simplest synapse meaning

A

one to one relay

22
Q

excitatory synapse at NMJ includes

A

single AP
acetylcholine released
nicotinic receptors (b/c ligand gated)
(open when they bind 2 Ach molecules, also permeable to Na+ and K+ ions)

23
Q

2 inhibitory transmitters in CNS

A

GABA

glycine

24
Q

inhibitory transmitters do this

A

open ion channels that are permeable to chloride ions
chlorine goes in, membrane is hyperpolarized (super negative)
IPSP (inhibitory postsynaptic potential) created

25
Q

inhibitory synapses are located on

A

proximal dendrites or cell body of target neuron

26
Q

AMPA receptor

A

L-glutamate
allow Na+ and K+ ions to pass and set up fast EPSPs
fast ionotropic signaling

27
Q

NMDA receptor

A

blocked by magnesium ions at RMP
once open, Na+, K+, and Ca2+ can get in
Ca2+ coming in is special - has to do with long term potentiation, learning, and depression

28
Q

transmitters involved in GPCR signaling (4)

A

norepi
serotonin
dopamine
L-glutamate

29
Q

peptide transmitters are stored in

A

large dense cored vesicles (LDCV)

30
Q

kinesin

A

a motor protein that moves macromolecules along microtubules. these macromolecules are involved in synthesis and storage of small transmitter molecules.

31
Q

denervation supersensitivity

A

upregulation of postsynaptic receptors following loss of presynaptic nerve due to damage; its a pathological change

32
Q

desensitization

A

when receptors are exposed to high conc of agonist (transmitter) for an extended period of time and they become unresponsive

33
Q

long term potentiation (LTP)

A
  • when central synapses are activated strongly and the number of receptors expressed in the postsynaptic membrane is increased/upregulated (can persist for hours/days)
  • increase in # AMPA receptors (upregulation) + phosphorylation of these receptors
34
Q

long term depression

A
  • when weakly activated central synapses show a down regulation of receptors that persists for hours or days
  • at glutamatergic synapses
  • dephosphorylation of AMPA receptors
  • triggered by diff levels of intracellular calcium

Physiology Test 1 (8 decks)

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