physio block 3

Question 1

What are the 3 parts of the Neuromuscular junction?

Answer 1

1. Presynaptic cleft
2. Synaptic cleft
3. post synaptic cleft

Question 2

What is the motor unit?

Answer 2

motor neuron + muscle fiber innervate

Question 3

What is the purpose of SNARE proteins?

Answer 3

it helps fuse, dock, and release acetylcholine from the presynaptic cleft into the synaptic cleft (exocytosis)

Question 4

What helps to increase the surface area of the post synaptic cleft?

Answer 4

Subneural clefts/ junctional folds

Question 5

Where does acetylcholine bind on the postsynaptic cleft?

Answer 5

Nicotinic acetylcholine receptors (ligand gated), opens Na channels

Question 6

How is acetylcholine removed from the synaptic cleft?

Answer 6

With acetylcholinesterase (enzyme), this prevents continuous muscle re excitation

Question 7

What is the problem that leads to overstimulation of nicotinic receptors?

Answer 7

Organophosphate- irreversible
Carbamate= reversible

Inactivates acetlychlolinesterase, so acetylcholine cant be removed.. causing overstimulation

causes animal poisoning

Question 8

What is myasthenia gravis?

Answer 8

reduction of Acetylcholine receptors

antibodies can block the ion channels so the muscle cant contract.

leads to muscle fatigue.

can be congenital or acquired

Question 9

What is botulism?

Answer 9

ingestion of neurotoxin by anaerobic bacteria

prevents release of Acetylcholine from vesicles

Causes:
1. Muscle paralysis
2. loss of vision
3. unable to swallow
4. could cause death

Question 10

How is Ca+ put back into the sarcoplasmic reticulum in skeletal muscle?

Answer 10

SERCA 1a (Ca+ pump) (primary active transport)