The Synapse

Question 1

What is the soma of a neuron

Answer 1

Synthetic and metabolic centre
Contain nucleus, ribosomes, mito, ER
Integrate incoming signals that are conducted passively to axon hillock

Question 2

What is the axon hillock

Answer 2

Site of initiation of the all or none AP

Question 3

What is an axon

Answer 3

Conducts out out signals as APs to other neurones

Mediated transport of materials between soma and presynaptic terminal

Question 4

What is a synapse

Answer 4

Point of chemical communication between neurones

Question 5

What are key structural elements of the chem synapse

Answer 5

Pre and post synaptic mems sep by a narrow synaptic cleft
Matrix of fibrous extracellular protein in cleft that hold pre and post syn mems together
Vesicles in presynaptic terminal that store neurotransmitter
Mem differentiations - preysnaptically active zones around vesicles cluster
- postsyn contains neurotransmitter receps

Question 6

What are the classifications of synapses

Answer 6

Gary’s type 1. - asymmetrical syn which mems differentiation on postsyn side is thicker than on presyn side
Excitatory

Grays you 2 - symmetrical synapses which mem differentiations are. Of similar thickness
Inhibitory

Question 7

What are some types of synapse

Answer 7

Classed morphologicalky byy location of presyn terminal on postsyn cell

Axodendritic - axon to dendrite very common

Axosomatic - axon to soma common

Axoaxonic - axon to axon uncommon

Question 8

What are the functional types of synapse

Answer 8

Excitatory - cns the transmitter is glutamate which activates postsyn cation, ionotropic glutamate receps which gen a local excitatory depo effect - excitatory postsyn potential

Inhibitory - cns transmitter GABA or glycine, activates postsyn anion receps gen a local inhib effect hyperporlarising - inhibitory postsyn potentail

Question 9

What are the major amino acid neurotransmitters in the cns

Answer 9

Glutamate
GABA
Glycine

Question 10

What is spatial summation

Answer 10

Many inputs converge upon a neurone to determine its output

Question 11

What is a temporal summation

Answer 11

A single input may modulate output by variation in AP frequency of that input

Question 12

What are temporal and spatial summations

Answer 12

Not isolated but are complementary processes

Question 13

What are amino acid and amine neurotransmitters released form

Answer 13

Synaptic vesicles

Question 14

What are peptide neurotransmitters released from

Answer 14

Secretory vesciles

Question 15

What activates ionotropic ligand-gated ion channels

Answer 15

Glutamate 
GABA 
Glycine 
ACh 
5-HT

Question 16

All but ‘what’ can activate metabotrophic GPCR’s

Answer 16

Glycine

Question 17

What are some amine neurotransmitters

Answer 17

ACh 
Dopamine
Histamine
Noradrenaline 
Serotonin

Question 18

What are some peptide neurotransmitters

Answer 18

Cck
Somatostatin
TRH

Question 19

Give an overview of neurochemical transmission

Answer 19

Intake precursor 
Syn transmitter
Store transmitter
Depo by AP 
Calcium influx through voltage activated calcium channels 
Calcium induced release of transmitter 
Receptor activation 
Enzyme mediated inactivation of transmitter
Reuptake of transmitter

Question 20

Glycine and glutamate occur in

Answer 20

All cells not just neurones

Question 21

GABA and amines must be

Answer 21

Specially syn by neurones with specific enzymes

Question 22

Where are the specific enzymes used for gaba and amine production produced and what do they do

Answer 22

Syn in cell body and trans to presyn terminal by axoplasmic transport

At terminal enzymes mediate syn within cyto of neurotrans form precursor subs

Question 23

What concentrates neurotransmitters

Answer 23

Conc in vesicles by transporters embedded in vesicle mem

Question 24

What is the syn and storage of neurotransmitters

Answer 24

Syn of precursor peptide by ribosomes at ER

Cleavage of precursor peptide in Golgi apparatus yielding active neurotransmitters

Sec granules bud off from the Golgi apparatus

Sec granules are trans to presyn terminal by fast axoplasmic trans

Question 25

What are the key features of the exocytosis of amino acid and amine neurotransmitters

Answer 25

Synaptic vesciles ready for rapid release are held in apposition to presyn mem in docking SNARE complex

Depo fo presyn mem opens voltage activated calcium channels causing a rise in conc of calcium in vicinity of docked vesciles

Calcium binds to synaptotagmin-1 ion vesicle mem causing vesicle to fuse to presyn mem

Neurotransmitter diffuses from vesicle to cleft

Mem added to presyn terminal and retrieved by endocytosis

Question 26

What are ligand gated ion channels

Answer 26

Aka, ionotropic receps

Consist of sep glycoproteins that form central, ion conducting, channel

Allow rapid change in perm of mem to certain ions

Rapidly alter mem potentail

Question 27

What are GPCR’s

Answer 27

Aka metabotrophic receps

Receptor, G protein and enzyme sep

G protien couples receptor activation to effector modulation

Signalling via G proteins relatively slow in comparison to ligand gated ion channels

Question 28

What are dendrites

Answer 28

Recieve inputs from other neurones and convey graded electrical signals passively to the soma