L8: drugs affecting neuromuscular junction

Question 1

How many processes can drug affect to modify chemical synaptic transmission?

Answer 1

5

Question 2

What processes pre-synaptically can affect the synaptic transmission?

Answer 2

• Synthesis
• Storage
• Release
  of the neurotransmitter

Question 3

What processes post-synaptically can affect the synaptic transmission?

Answer 3

• Receptors
• Removal mechanism
  for the neurotransmitter

Question 4

First stage of events in pre-synaptic ‘cholinergic’ transmission

Answer 4

Acetylcholine is synthesised from choline + acetylcoenzyme A by action of enzyme Choline Acetyl Transferase (CAT)

Question 5

Second stage of events in pre-synaptic ‘cholinergic’ transmission

Answer 5

Choline is taken into nerve terminal by a transporter protein

Question 6

Third stage of events in pre-synaptic ‘cholinergic’ transmission

Answer 6

ACh is stored by synaptic vesicles that are released by exocytosis

Question 7

First stage of post-synaptic events in cholinergic transmission

Answer 7

After being released, ACh diffuses across synaptic gap & activates receptors on post-synaptic membrane

Question 8

Two types of ACh receptors

Answer 8

1) Nicotinic Receptors
2) Muscarinic Receptors

Question 9

What are nicotinic receptors activated by?

Answer 9

Nicotine from tobacco plant

Question 10

What are muscarinic receptors activated by?

Answer 10

Muscarine from poisonous Fly Agaric mushroom

Question 11

What is ACh broken down by during the removal from the synapse?

Answer 11

Enzyme acetylcholinesterase (AChE), found in the synaptic gap

Question 12

Name the enzyme involved in the synthesis of acetylcholine (ACh)

Answer 12

Choline Acetyl Transferase (CAT)

Question 13

Name the enzyme involved in the destruction of ACh

Answer 13

Acetylcholinesterase (AChE)

Question 14

What happens to the choline produced following the destruction of ACh?

Answer 14

Being recycled, taken back into nerve terminal for synthesis of new ACh

Question 15

What are the FIVE key processes that drugs can interfere with at any chemical synapse

Answer 15

1) Synthesis
2) Removal
3) Release
4) Receptors
5) Removal

Question 16

What is the motor unit?

Answer 16

Motor nerve + muscle fibre it controls

Question 17

Why is the muscle membrane thrown into folds?

Answer 17

Increasing SA

Question 18

What is the specialised area of the muscle membrane called?

Answer 18

Muscle “end plate”

Question 19

What is the neurotransmitter released in skeletal neuromuscular junction?

Answer 19

Acetylcholine

Question 20

What is the receptor present on the muscle in skeletal neuromuscular junction?

Answer 20

Nicotinic acetylcholine receptors

Question 21

Define agonist

Answer 21

Substance that mimics the actions of a neurotransmitter to produce a response when it binds to a specific receptor

Question 22

How many protein subunits form the nicotinic ACh receptor?

Answer 22

5

Question 23

Structure of nicotinic ACh receptor

Answer 23

5 protein subunit surrounding a non-selective cation channel which is permeable to Na+ & K+

Question 24

When does the non-selective cation channel on the nicotinic ACh receptor open?

Answer 24

2 molecules of ACh bind to the protein complex, 1 to each alpha-subunit

Question 25

What does opening of the channel of nicotinic ACh receptor leads?

Answer 25

Leads to depolarisation of the end-plate region of muscle membrane

Question 26

What is botulinum toxin?

Answer 26

Medication used to treat therapeutic & cosmetic purposes

Question 27

What is blepharospasm?

Answer 27

Involuntary tight closure of eyelids

Question 28

What does botulin target in blepharospasm?

Answer 28

Inappropriate contraction of the skeletal muscle

Question 29

Does botulinum toxin given locally or systemically?

Answer 29

Locally

Question 30

Role of botulin in presynaptic transmission

Answer 30

Inhibits the release of ACh

Question 31

Define antagonist

Answer 31

Substance that stops the action/effect of another substance

Question 32

What are at the nicotinic ACh receptor to post- synaptically inhibit neuromuscular transmission?

Answer 32

Reversible competitive antagonists

Question 33

Are reversible competitive antagonists GENERAL ANAESTHETICS?

Answer 33

NOOO, used alongside to stop contraction

Question 34

How can effects of muscle relaxants during surgery be reversed?

Answer 34

Acetylcholinesterase inhibitor, neostigmine