Synaptic Transmission Flashcards by Natalie Slaughter

Electrical Synapse

consists of one or more gap junction channels permeable to ions and small molecules

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Properties of electrical synapses

bidirectional
fast
low selectivity

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Examples of an electrical synapse

astrocytes, epithelial supporting cells

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Connexon

formed by 6 connexins

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What does Electrical synapse allow passage3 of

small water soluble molecules/ions

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Neuromuscular synapse

between a motor neuron and muscle fiber

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2 types of chemical synapses

CNS and Neuromuscular

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Active zone of a CNS synapse

specialized for vesicular release of neurotransmitters

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synapse

where neuron-neuron interaction takes place

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one way conduction

the signal goes best one way

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Presynaptic terminal

docking complex located herer

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docking complex

holds vesicles before they are ready to be realized

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synaptic delay

Time interval between when action potential invades the pre-synaptic terminal and when a membrane potential change begins in the post-synaptic cell.

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What type of receptors (ionotropic vs metabotropic) is associated with long synaptic delay times?

metabotropic

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Is the synaptic delay shorter at chemical synapses or electrical synapses?

chemical

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ionotropic

ligand gated ion channel

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metabotropic

6 protein coupled receptor

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What are the 3 ways to remove neurotransmitters from the synaptic cleft

Diffusion
Enzymatic degradation
Transmitter re-uptake either into presynaptic terminal or into adjacent astroglia

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acetylcholinesterase

hydrolyzes acetylcholine and can stop the end-plate potential

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Spacial summation

Occurs when two or more separate postsynaptic potentials reach the initial segment simultaneously

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Temporal summation

Occurs when a single presynaptic terminal has two or more action potentials in rapid succession. The first postsynaptic potential has not died away when the next occurs. This temporal overlap enables the potentials to sum.

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nicotinic Ach

fast, ionotropic receptor

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muscarinic Ach receptor

slower, metabotropic receptor , binds to G protein

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Which receptors are the biogenic amines

Catecholamines
Seretonin
Histamine

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What are the catecholamines

Dopamine Norepinephrine Epinephrine

Dopamine

metabotropic

Norepinephrine

binds to adrenergic/noradrendergic receptors | has a greater affinity for alpha adrenergic receptors

Epinephrine

binds to adrenergic/noradrenegric receptors | has greater affinity for beta adrenergic receptors

Serotonin

binds to several different types of 5-HT receptors

Histamine

metabotropic

GABA

major CNS inhibitory transmitter

GABA a

directly gated channel for Cl- | benzos and barbiturates can bind here

GABA b

metabotropic receptor, has an inhibitory effect by opening K+ channels or suppression of Ca++

Glycine

inhibitory | opens directly gates Cl- channel

What can the glycine receptor be blocked by?

strychnine

Tetanus toxin

interferes with the release of glycine from inhibitory interneurons in the spinal cord

Glutamate

excitatory

Aspartate

excitatory

Excitotoxicity

neurons can be overexcited and destroyed by an unusually high accumulation of glutamate and related compounds. There is evidence that excitotoxicity is an important cause of neuronal damage after oxygen deprivation.

Adenosine

a neuromodulator which is not stored in vesicles

Adenosine acts as a general CNS _______

depressant

Neuroactive peptides may act as what?

may act as hormones or neurotransmitters or neuromodulators

diffuses out of cell it's produced in and affects nearby cells can't be contained in a vesicle short lived actions

endocannabinoids produced by what

enzymatic degradation of membrane lipids.

What are the endocannabinoid receptors?

CB1 CB2

What does THC bind to?

CB1 and CB2

Myasthenia gravis

an autoimmune disease which reduces the number of acetylcholine receptors at the postsynaptic neuromuscular junction.

Symptoms of Myasthenia gravis

muscle weakness or even paralysis

Clostridial toxins (botulism)

interfere with release of presynaptic plasma membrane proteins

Eaton-Lambert syndrome

pre-synaptic | caused by autoimmune attack on voltage – gated Ca++ channels in the terminals of somatic motor nerves.

SNARE compelx

several specific transmembrane proteins located at vesicles and presynaptic plasma membrane form a helix complex for vesicle docking and fusion

what happens during recovery

Ca++ channels close Ca++ gets sequestered in ER and removed vesicles endocytosed

ionotropic receptor characterics

rapid changes in membrane poential

metabotropic receptor characertics

slow change in membrane potential

what is the most abundant synpase in the nervous system

glutamaterigc synpase using gluatmate as transmitter

what are glutamate gated ion channels permeable to

Na+ and K+

what is the primary inhibtory neurotransmitter

GABA

FOr Cl-, what is stronger? the chemical force or electrical force

chemical

how do metabotropic receptors cause excitatory effects

decreasing conduction through chloride or potassium channels

how do metabotropic receptors cause inhibitory effects

increasing conduction through chloride or potassium channels

how do TCAs work

block uptake of 5-HT

active zone

part of pre-synpatic membrane taht is specialized for vesicular release of neurotransmitter

how many active zones are at NMJ

multiple

how many active zones are at CNS synpases

features of neumuscle transmittion

only one motor neuron innervates skeletal muscle fiber only excitory only one type of neurotransmitter and receptor strong synpoatic transmission

what is the one type of neurotransmitter in NMJ

acetylcholine

what is the one type of receptor at NMJ

nicotinic acetylcholine receptor

how do tetanus and botulinum toxins work

cleave SNARE proteins

what does botulinum specifically do

attacks motor neuron | causes NMJ paralysis and muscle weakness

what does tetanus specifically do

attack inerneuron | causes disinhibition, hyperexcitation, and tetanic contraction

who does Eaton Lamberty syndrome happen in

patietns with small cell carcinoma of lung

symptom of eaton lambert syndrome

muscle weakness

neostigmine

reversible AchE inhibitor

alpha-bungarotoxin

irreversibiliyt blocks nAchR

tubocurarine

blocks acetylcholine receptors

edrophonium

short acting inhibitory of cholinesterase. used to treat myasthenia gravis

pesticides/sarin do waht

bind irreversibly to cholinesterase. poison

characteristics of a neurotransmitter

packed into vesciles Ca++ dependent release bind to specific receptor

when can NMDA receptor open

only during depolarization of postsynaptic neuron

Synaptic Transmission Flashcards

(79 cards)