Nervous System - Synapse

Question 1

Structure of synapse

Answer 1

Synaptic knob - end of axon terminal
Pre-synaptic membrane
Calcium voltage gated channel
Synaptic vesicle
Neurotransmitters

Synaptic cleft

Post synaptic membrane
Neurotransmitter receptors + ion channel

Question 2

Events during transmission across synapse

Answer 2

1)Positive charge open Ca2+ channel
2)Ca2+ bind to SNARE protein (protein connected to vesicle + pre-synaptic membrane)
-Ca2+ pump available to pump Ca2+ out

3)cause SNARE protein to drag vesicle to membrane
4)exocytosis - vesicle fuse to membrane wall = release NT

4)NT diffuse + bind to receptors and open ion channel for excitatory (Na) or inhibitory (K)

5)enzyme break break down NT complementary from receptor, transporter transport NT back to vesicle - prevent constant stimulation

6) NT regeneration in pre synaptic membrane

Question 3

Excitatory NT and inhibitory NT

Answer 3

Excitatory open Na channel so sodium diffuse in cell
-increase charge value for action potential

Inhibitory open K channel so K diffuse out of cell
-decrease charge value to prevent action potential

(High Na out of cell, low K out of cell)

Question 4

Why is synapse important

Answer 4

Make sure impulse only go one way
-only vesicle in pre-synaptic neurone
-only receptor in post-synaptic neurone

Allow for refractory periods for neurone to rest
Only allow nerve impulse to travel if enough stimuli is met

Question 5

What is synapse between neurone called

Answer 5

Cholinergic synapse

Question 6

Neuromuscular junction

Answer 6

Synapse between neurone + muscle
-post synaptic membrane is muscle fibre membrane (Sarcolemma)
-cause depolarisation = muscle contract

Question 7

How excitatory drug affect synapse

Answer 7

Most are agonist - cause more depolarisation of post synaptic neurone
-inhibit enzyme that break down NT
-act as substitution for NT
-cause more exocytosis

Tolerance:
-less receptors or NT to remain normal

Withdrawal:
-body only used to equilibrium from drugs

Question 8

How does inhibitory drug work

Answer 8

Most are antagonist - prevent depolarisation
-cause hyper-polarisation in post synaptic neurone
-block receptor
-block calcium ion channel

Tolerance
-more NT or receptor