Synaptic Transmission

Question 1

Where does communication between neurons occur

Answer 1

Through a junction called a synapse

Question 2

What is the anatomy of a synapse

Answer 2

Pre synaptic neuron - releases neurotransmitter, contains synaptic vesicles (containing neurotransmitter)
Synaptic cleft
Post synaptic neuron/target cell - contains receptors for neurotransmitter

Question 3

What are the 7 important features of the synapse
PSPRVSE

Answer 3

Presynaptic nerve terminal
Synaptic cleft
Postsynaptic nerve terminal
Receptors in postsynaptic cell membrane
V. Gated Ca2+ channels in presynaptic nerve terminal
Synaptic vesicles containing neurotransmitter
Enzyme for neurotransmitter inactivation

Question 4

What is cholinergic transmission

Answer 4

Neurotransmission regulated by acetylcholine

Question 5

What are the 5 events of cholinergic transmission

Answer 5

1: Action potential triggers opening of voltage gated calcium channels
2: Calcium ions diffuse into axon terminal, and trigger exocytosis of acetylcholine vesicles
3: Acetylcholine diffuses across synaptic cleft, binds to ACh gated sodium channels, and produces excitatory postsynaptic potential
4: Once open, receptor-ACH affinity decreases. Depolarisation ends as ACh is cleaved into acetate and choline by acetylcholinesterase
5: axon terminal reabsorbs choline from synaptic cleft (recycled into ACh)

Question 6

What structures allow electrical synapses

Answer 6

Gap junctions (cytoplasm continuity of two adjacent cells)

Question 7

What are electrical synapses

Answer 7

Synapses where, through gap junctions, depolarisation from presynaptic cell passes directly to post synaptic cell

Question 8

What does electrical synapses not allow

Answer 8

Signal modulation

Question 9

What are the sizes of Nerve-Nerve synapses and Nerve-Muscle synapses

Answer 9

Nerve nerve are tiny - each may be one of thousands on the post synaptic cell
Nerve muscle are huge - each muscle fibre receives input from only one neuron at one site

Question 10

What are the differences between action potentials of nerve-nerve vs nerve-muscle synapses

Answer 10

Nerve - Nerve: AP in individual neuron will rarely bring partner to threshold
Nerve - Muscle: AP in neuron very likely to bring muscle fibre to threshold

Question 11

What are the differences in between types of inputs of Nerve-Nerve and Nerve-Muscle synapses

Answer 11

Nerve-Nerve synapse inputs may be excitatory or inhibitory. Many neurotransmitters used
Nerve-muscle synapse inputs are only excitatory. Only ACh used