Communication at the neuromuscular junction/ Roles of acetylcholine and acetylcholinesterase

What is the point where a nerve fiber meets any target cell called?

A) Synapse | B) Synaptic cleft | C) Basal lamina | D) Junctional fold

Synapse

What is the synapse called when a nerve fiber meets a skeletal muscle fiber?

A) Axon terminal | B) Synaptic vesicle | C) Neuromuscular junction | D) Basal lamina

Neuromuscular junction (NMJ) (also called the motor end plate)

What is the bulbous swelling at the end of a nerve fiber inside a synapse called?

A) Junctional fold | B) Synaptic cleft | C) Basal lamina | D) Axon terminal

Axon terminal

What is the narrow gap (60 to 100 nm wide) separating the axon terminal from the muscle fiber?

A) Motor end plate | B) Synaptic cleft | C) Synaptic vesicle | D) Sarcoplasmic reticulum

Synaptic cleft

Which chemical neurotransmitter is stored in synaptic vesicles and released by exocytosis to stimulate muscle contraction?

A) Acetylcholine (ACh) | B) Acetylcholinesterase (AChE) | C) Myoglobin | D) Dystrophin

Acetylcholine (ACh)

Why does the sarcolemma at the NMJ have deep infoldings called postsynaptic membrane folds (junctional folds)?

A) To store extra calcium | B) To anchor thick myosin filaments | C) To block acetylcholine release | D) To increase area for ACh receptors

To increase area for ACh receptors

Which autoimmune disease results from a deficiency of ACh receptors on the muscle fiber?

A) Muscular dystrophy | B) Myasthenia gravis | C) Fibrosis | D) Rigor mortis

Myasthenia gravis

Which collagen and glycoprotein mat encloses the entire NMJ and passes through the synaptic cleft?

A) Endomysium | B) Sarcolemma | C) Basal lamina | D) Perimysium

Basal lamina

Which enzyme in the synaptic cleft breaks down ACh to turn off contraction and allow the muscle to relax?

A) Acetylcholinesterase (AChE) | B) Calsequestrin | C) Acetylcholine (ACh) | D) Myosin ATPase

Acetylcholinesterase (AChE)

How does a nerve impulse cross the synaptic cleft to stimulate the muscle fiber?

A) By jumping directly across as an electrical spark | B) Through gap junctions in the basal lamina | C) By traveling down T tubules inside the axon | D) By exocytosis of ACh acting as a chemical messenger

By exocytosis of ACh acting as a chemical messenger