Sessoin 5- Ligand Gated Channels

Question 1

What ion channels are present at the nerve terminal?

Answer 1

V-gated Na+, K+ and Ca2+

Question 2

How are the Ca2+ channels opened?

Answer 2

Membrane depolarisation due to the AP

Question 3

What happens when the Ca2+ channels open?

Answer 3

Massive influx of Ca2+ down concentration gradient

Question 4

What is the role of Ca2+ in neurotransmitter release?

Answer 4

Binds to synaptotagmin, allows vesicle to bond

Question 5

What is the role of the SNARE complex?

Answer 5

Forms a fusion pore, allowing the release of neurotransmitter

Question 6

What is the neurotransmitter used at neuromuscular junctions?

Answer 6

Acetylcholine

Question 7

What is myasthenia gravis?

Answer 7

Autoimmune disease that attacks nAChR
Endplate potentials reduced
Muscle weakness and fatigue

Question 8

What happens when ACh binds at the endplate?

Answer 8

Activates nAChR

Depolarisation

Question 9

What is a competitive nAChR blocking agent?

Answer 9

Molecule competetively binds to nAChR leading to a loss of function e.g d-tubocuraine

Question 10

What is a depolarisation blocker?

Answer 10

Blocks adjacent v-gated Na+ channels and so inhibits depolarisation e.g succinylcholine

Question 11

How do mACh receptors differ from nAChRs?

Answer 11

mAChR produce a slower response as they are coupled to G-proteins which trigger a signalling cascade in the cell
nAChR are themselves ion channels to act faster