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Semester 2 FS Exam 1 > Synaptic Events > Flashcards

Synaptic Events Flashcards

(58 cards)

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1
Q

Connexon is formed by

A

6 protein subunits called connexins

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2
Q

Connexons make

A

1 connexon = half a channel

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3
Q

How far apart are cell membranes in gap junctions

A

3.5nm

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4
Q

CNS Synapse - cleft is

A

20-40nm in space

Pre and post synaptic membranes are held together by extracellular matrix and proteins like neurexins

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5
Q

Presynaptic density - CNS Synapse

A

docking complex

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6
Q

Postsynaptic density - CNS Synapse

A

receptors, binding proteins

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7
Q

Active zone - CNS Synapse

A

part of the presynaptic membrane that is specialized for vesicular release of NTs

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8
Q

Features of CNS synapse

A

unidirectional

can be excitatory or inhibitory

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9
Q

AP –> NT release CNS Synapse

A
  1. NT in vesicles are docked
  2. AP invades presynaptic terminal and depolarizes the membrane
  3. Ca channels open and Ca flows into the cell
  4. This inc probability that vessels in active zone will fuse with presynaptic membrane and release a transmitter
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10
Q

Recovery phase CNS Synapse

A
  1. K leaves the cell
  2. Ca channels close
  3. Free Ca is removed via diff mechanisms
  4. Synaptic vesicles are removed - recylced
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11
Q

Ionotropic Receptors

A

ligand gated
Binding of NTs directly changes channel’s permeability to ions
Responsible for fastchemical synaptic transmission

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12
Q

Metabotropic Receptors

A

G protein coupled receptors
Slower acting
Binding of NTs initiates G protein mediated signaling

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13
Q

EPSP

A

NT binds to excitatory receptor
Glutamate = major excitatory NT
Permeable to Na and K but more to Na
GLutamate binds to ligand gated receptor –> opens the channel –> influx of Na –> depolarization
One EPSP is usually not enough to elicit AP

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14
Q

IPSP

A

NT binds to inhibitory receptor
GABA = major inhibitory NT
Permeable to Cl
Cl flows in –> hyperpolarizes membrane

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15
Q

Synaptic delay

A

time btw when AP invades pre synaptic terminal and when membrane potential change begins in post synaptic cell

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16
Q

Causes of synaptic delay

A

Events leading to fusion of synaptic vesicle with presynaptic membrane
Diffusion of transmitter across synaptic cleft
Activation of postsynaptic channels

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17
Q

How are NTs removed from the synaptic cleft

A

Diffusion
Enzymatic degredation
Transmitter re-uptake

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18
Q

Spatial Summation

A

two or more separate postsynaptic potentials reach the initials segment simultaneously

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19
Q

Temporal summation

A

when single presynaptic terminal has two or more action potentials in rapid succession
The first has not died when the next occurs - temporal overlap enables the potentials to sum

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20
Q

NMJ

A

specialized synapse btw a motoneuron and a muscle fiber

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21
Q

Presynaptic Structure

A

as motoneuron axon approaches its termination it loses the myeling sheath and divides into number of terminal boutons

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22
Q

Postsynaptic Membrane Structure

A

Junctional folds, motor end plate

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23
Q

Synaptic Transmission at NMJ

A

AP reaches end of axon –> depolarized Ca channels open –> Ca flows in –> release Ach –> Ach diffuses across cleft and binds to receptors at end plate –> Na flows in and K flows out –> depolarization (EPP) –> Depolarization spreads and causes an AP –> terminated by hydolysis of Ach by Achesterase

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24
Q

Gap junction and Electrical synapse

Study These Flashcards
A

Need gap junction for electrical synapse but can have gap junction without an electrical synapse

25
Electrical Synapse
Consists of one or more gap junction channels permeable to small ions and molecules
26
Location of electrical synapses and/or gap junctions
``` Nervous system Myocardial cells Intestinal smooth muscle Cochlea NOT in adult skeletal muscles (would send to entire muscle versus specific muscle) ```
27
Autocrine chemical signaling
When there are receptors on presynaptic cell for transmitter that cell releases
28
Hormone - neurohormone
Neurohormone if substance is released into bloodstream by NT
29
NT
Distributed locally by diffusion Released at a synapse by a neuron Synaptic mechanism when post synaptic cell very close Paracrine mechanism when several near by post synaptic cells
30
Neuromodulator
can affect release of NT or function or number of NT receptors
31
Synaptic Efficacy
Capacity for producing a desired result or effect - effectiveness
32
Catecholamines
Dopmaine Norepinephrine Epinephrine
33
Biogenic amine
all catecholamines plus Serotonin Histamine
34
Cocaine
attaches to dopamine transporter and blocks the normal recycling process resulting in a buildup of fopamine in the synapse which leads to the pleasurable effects
35
Downregulation of Neuroreceptors
Inc amount of stimulation of their G coupled protein receptors cause post synaptic cell to decrease the number of receptor for the transmitter - this is important in understanding why B agonists can lose their effectiveness
36
Downregulation of autoreceptors
SSRI depressants - can cause more serotonin in the interstitial fluid around the cell - by inc stimulation of serotonin autoreceptors a SSRI might dec the amount of autoreceptors - downregulation could increase the release of serotonin and inc effect on post synaptic cell
37
Acetylcholine
Ach A small molecule neurotransmitter Nicotinic (ionotropic) and muscarinic (metabotropic) Acetylcholine receptors
38
Functions of Ach
Important in autonomic NS | Important in CNS
39
Dopamine
5 subtypes of receptors D1 D2 D3 D4 D5 | All metabotropic
40
Functions of Dopamine
Pathway abnormalities --> Schizophrenia, parkinsons Some antipsychotic drugs act by blocking the binding of dopamine to its receptor Some drugs of abuse act by interfering with re-uptake of dopamine in brain
41
NE
Norepinephrine Binds to adrenergic/noradrenergic receptors Greater affinity to Alpha adrenergic
42
Functions of NE
Released from adrenal medulla as part of fight/flight response Also involved in control of alertness vs sleep
43
Epinephrine
Binds to adrenergic/noradrenergic receptors | Greater affinity to Beta adrenergic
44
Serotonin
5HT Biogenic amine - Indolamine - NOT catecholamine Binds to serotonin receptors (metabotropic)
45
Functions of serotonin
SSRIs that are used to treat depression
46
Histamine
Diamine Receptors H1 H2 H3 H4 All metabotropic
47
Functions of histamine
Penetrate the blood brain barrier - sedating
48
GABA
Amino Acid transmitter - small molecule transmitter Present throughout CNS and is major CNS inhibitor GABA A - Directly gated channel for Cl (ionotropic) GABA B - Metabotropic - inhibitory
49
Glycine
Binds to ionotropic receptor - opens Cl channel, inhibitory effect
50
Glutamate and Aspartate
at least eight diff types of metabotropic glutamate receptors (mGluRs) 3 diff classes of ionotropic receptors
51
Purines
Part of ATP - ATP binds to P type purinergic receptors | All G protein coupled receptors
52
Neuroactive Peptides
Hormones, NTs, or NMs | Release is triggered by trains of APs which cause large amounts of Ca to enter nerve terminal
53
Gaseous NT
nitric oxide
54
Endocannaboids
produced by enzymatic degredation of membrane lipids Action is ended by re-uptake CB1 and CB2 receptors CB1 are most common G coupled receptors in the brain
55
Myesthenia Gravis
Postsynaptic Autoimmune Reduces number of Ach receptors at post NMJ Less receptors so EPP smaller - muscle weakness
56
Eaton-Lambert Syndrome
Presynaptic Autoimmune Antibodies that attack on voltage gated Ca channels in somatic motor nerves
57
Botulinum Toxin
Presynaptic Autoimmune Cleave diff spots on eithe rsynaptic vesicle or presynaptic plasms membrane proteins - interferes with release of NT at NMJ - muscle paralysis
58
Tetanus
Presynaptic Protease that cleaves a synaptic vesicle protein and itnerferes with release of glycine from inhib interneurons in spinal cord - muscles all contracted since affecting inhibition

Semester 2 FS Exam 1 (3 decks)

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