Synapses

Question 1

Divergence

Answer 1

Each neuron makes synaptic contact with thousands of others.

Question 2

Convergence

Answer 2

Each neuron receives thousands of synapses from others

Question 3

Classifying a synapse

Answer 3

Morphological variations - bifunctional,reciprocal,classical.
Various vesicle forms
Various locations - postsynaptic,axonal,dendritic,presynaptic.
Chemical or electrical.

Question 4

Dendrites

Answer 4

Spines introduce temporal component
Dendrites process signals locally.
Somata,spines and dendrites can signal retrogradely,onto axons etc.

Question 5

Neurotransmitters

Answer 5

Amino acids - Excitatory (glutamate,aspartate), Inhibitory (GABA, glycine).
Amines - indolamines (5HT), catecholamines (NA, dopamine).
ACh.
Purines - ATP, adenosine.
Peptides - enkephalins, NPY, NK, CCK.

Question 6

Classical criteria for identifying a neurotransmitter

Answer 6

Presence in neurons
Synthetic process
Removal process
Release on stimulation
Actions mimic stimulation
Inactivation of removal removal increases effects.
Antagonists block stimulation.

Question 7

Complications of neurotransmitters

Answer 7

Multiple receptors and effectors
Extrasynaptic receptors
Co-transmission
Allosteric modulation
Temporal variations of action.
Genetic effects

Question 8

Sites for drug action

Answer 8

Preventing AP in nerve
Preventing calcium entry
Preventing exocytosis
Depleting vesicles
Stopping synthesis
Affecting biotransformation
Acting on transduction mechanism
Providing false transmitter
Preventing precursor uptake
Blocking reuptake
Action on presynaptic receptors
Displacing transmitters
Acting on postsynaptic receptors

Question 9

Glutamate

Answer 9

7tm g-protein coupled receptors
3 groups
Group I - activate PLC
Group II and III -inhibit cAMP.