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NEUROPHYSIOLOGY > NS 1 - PT 2 > Flashcards

NS 1 - PT 2 Flashcards

(60 cards)

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1
Q

Name the 2 types of synapses

A

Chemical and electrical synapses

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2
Q

Explain electrical synapses

A

Characterised by gap junction with ion channels that connect the cytoplasm of adjacent cells

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3
Q

Function of gap junctions

A

Allow free movement of ions from the cytoplasm of one cell to the next

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3
Q

Function of electrical sunapses

A

Allow bidirectional transmission of impulses

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4
Q

Explain chemical synapses

A

Characterised by the secretion of a neurotransmitter

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5
Q

Which type of synapse is abundant in the CNS

A

Chemical neurotransmitter

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6
Q

How many known neurotransmitters are there?

A

More than 50

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7
Q

Membrane of the presynaptic terminal is called the_______________

A

Presynaptic membrane

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8
Q

Which ion channel is abundant in the presynaptic membrane?

A

Voltage-gated calcium channels

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9
Q

Explain synaptic transmission

A

AP depolarises the presynaptic membrane open the calcium channels and allow influx of calcium ions into the terminal.

Calcium influx cause transmitter vesicles in the presynaptic terminal to release their neurotransmitter into the synaptic cleft

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10
Q

What guides and promotes vesicle fusion with the cell membrane?

A

SNARE proteins
Synaptobrevin
*SNAP-25
*Syntaxin
*Synaptotagmin – Ca2+ sensing
Target for neurotoxins: Botulinum toxins

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11
Q

Chemical synapses transmit signals bidirectionally - true or false

A

f. they transmit in one direction from presynaptic neuron to postsynaptic neuron

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11
Q

What is the target site of neurotransmitters?

A

Receptors in the postsynaptic membrane

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12
Q

What is the action of neurotransmitter in the postsynaptic neuron?

A

Excitation, inhibition, or modify sensitivity

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13
Q

Types of postsynaptic membrane receptors

A

Ionotropic receptors and metabotropic receptors

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14
Q

Explain the mechanisms of postsynaptic excitation

A

Opening of sodium channels allows influx of positive electrical charges to flow to the interior of the postsynaptic cell

Decrease of chloride or potassium channels or both. Increased expression of excitatory membrane receptors or decreased expression of inhibitory membrane receptors

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15
Q

What membrane mechanisms receptors cause inhibition? (3)

A

Opening of chloride channels on the postsynaptic membrane
Increased efflux of potassium ions out of the neuron
Increased expression of inhibitory synaptic receptors, or decreased expression of excitatory receptors

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16
Q

What are neurotransmitters?

A

Endogenous chemicals in the brain that enable signalling across a chemical synapse

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17
Q

3 functions of neurotransmitters

A

Carry and modulate signals between neurons or other cell types

Act on a variety of targets to elicit biological functions

Cause electrophysiological changes in the postsynaptic cell (Excitation by depolarization or inhibition by hyperpolarization)

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18
Q

Explain synthesis and transport of neuropeptides

A

Neuropeptides are
synthesized in the cell
body and pre-loaded
into vesicles which are
delivered to the axon
terminal by axonal
transport.

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19
Q

Which types of receptors does glutamate act on?

A

Glutamate acts on both ionotropic and metabotropic receptors

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20
Q

How are glutamate receptors named? give examples

A

Glutamate receptors named after synthetic agonists that activate them.
* AMPA (amino-methylisoxazole propionic acid)
* Kainite
* NMDA (N-methyl-D-aspartate)

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21
Q

Repetitive activation of the NMDA receptor leads to what?

A

Long term potentiation

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21
Q

Influx of calcium ions leads to activation of ____________________ enzymes

A

Ca2+ dependent enzymes

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22
Action of calcium dependent enzymes once activated
They modify the structure and number of synaptic contacts in the target cell
23
Action of anaesthetic drug ketamine on NMDA channel
▪ Anaesthetic drug ketamine blocks the NMDA channel, also blocks memory formation
24
Which glial cell is responsible for taking up glutamate?
Astrocye
25
_______________ converts glutamate to glutamine
Glutamine synthase
26
Where is glutamine transported?
Into the nerve terminal
27
What happens to the glutamine once in the nerve terminal?
n the nerve terminal glutamine converted to glutamate by glutaminase. 5. Glutamate returned to a synaptic vesicle
28
Explain the process of glutamate reuptake and resynthesis
1. Glutamate is taken up by an astrocyte. 2. Glutamate is converted to glutamine by glutamine synthetase. 3. Glutamine is transported back into the nerve terminal. 4. In the nerve terminal glutamine converted to glutamate by glutaminase. 5. Glutamate returned to a synaptic vesicle.
29
Full name of GABA
Gamma-aminobutyric acid
30
Name the 2 major types of GABA receptors
ionotropic and metabotropic.
31
what happens when GABA receptors are activated?
▪ Activation of GABA receptors - channel pores opens and Cl− ions influx from the synaptic cleft to the cytosol – Hyperpolarisation
32
What receptors are activated when sedative hypnotic agents are administered?
Activation of GABA receptors
33
Examples of sedative hypnotic agents
barbiturates, benzodiazepines and alcohol
34
What is useful for the Rx of seizures? Why?
Barbiturates and benzodiazepines. They are Anticonvulsant
35
What drugs are GABA receptor antagonist?
Bicuculline. It is therefore a convulsant Picrotoxin
36
Which glial cell takes up GABA?
Astrocyte
37
Explain GABA reuptake and resynthesis (5)
1. GABA is converted to glutamate by GABA transaminase. 2. Glutamate is converted to glutamine by glutamine synthetase. 3. Glutamine is transported back into the nerve terminal and converted to glutamate by glutaminase. 4. Glutamate is converted to GABA by glutamate decarboxylase. 5. GABA returned to a synaptic vesicle
38
What neurotransmitter plays a role in learning and memory?
Acetylcholine
39
What causes onset of Alzheimer's disease?
Degeneration of cholinergic neurons is associated with the onset of Alzheimer disease
40
_________ is the main neurotransmitter in the NMJ
ACh
41
▪ Ionotropic ACh receptors are called ______________. ▪ Metabotropic ACh receptors are called __________.
nicotinic. muscarinic
42
Explain ACh synthesis (4)
▪ Choline from the extracellular fluid is sent to the nerve ending. ▪ Choline is acetylated by acetyl coenzyme A (acetyl CoA) released by mitochondria and the reaction catalysed by choline acetyltransferase (ChAT). ▪ Synthesized ACh molecules are taken up by synaptic vesicles. ▪ Released ACh binds with its receptor
43
Explain ACh degradation (2)
Acetylcholinesterase (AChE) hydrolyses the transmitter. ▪ The choline is transported back into the cytosol
44
Explain recycling of ACh (3)
Formation of a fresh molecule of ACh is mediated by the transferase, en route to a synaptic vesicle. ▪ Acetate is transported into the cytosol. ▪ Mitochondria use the acetic acid to produce fresh acetyl CoA
45
Examples of catecholamines
dopamine, norepinephrine, and epinephrine
46
Catecholamines are derived from which amino acid?
Tyrosine
47
Which catecholamine is associated with Parkinsons disease, drug addiction and schizophrenia?
Dopamine
48
What is the classic feature of Parkinson disease?
Degeneration of neurons in the substantia nigra
49
Explain catecholamine degradation
▪ Catecholamines molecules within the synaptic cleft are broken down by catechol Omethyltransferase (COMT). ▪ Surplus catecholamines molecules in the cytosol are degraded by mitochondriaderived monoamine oxidase (MAO) enzyme
50
Another name for serotonin
5-HT (5-hydroxytryptamine)
51
Serotonin is implicated in which conditions?
Serotonin is implicated in depression, insomnia, anxiety disorders.
52
Serotonin is derived from which amino acid?
Tryptophan
53
Tryptophan is converted to_________________ by the __________________ enzyme
5-hydroxytryptophan tryptophan hydroxylase.
54
5-hydroxytryptophan is converted to _____________________ by the _________________ enzyme
serotonin 5-hydroxytrytophan decarboxylase.
55
What returns serotonin to the cytosol?
Serotonin reuptake transporter
56
What degrades serotonin?
monoamine oxidase (MAO).
57
Name 2 antidepressants
SSRI: Selective Serotonin Reuptake Inhibitor ▪ MOA: Monoamine oxidase A inhibitors

NEUROPHYSIOLOGY (2 decks)

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