Question

Which one of the following components stimulates contraction of a skeletal muscle?

Select Answer:
- synaptic cleft
- muscle fiber
- motor neuron
- acetylcholinesterase

Answer 1

Motor neurons stimulate contraction of skeletal muscles by releasing acetylcholine at the neuromuscular junction, which binds to receptors on the muscle fiber and initiates contraction.

Step-by-step explanation:

The component that stimulates contraction of a skeletal muscle is the motor neuron. The process begins when an action potential travels down the motor neuron's axon to the neuromuscular junction. Here, the neuron's synaptic end bulbs release the neurotransmitter acetylcholine (ACh), which then diffuses across the synaptic cleft and binds to receptors on the muscle fiber sarcolemma. This binding triggers depolarization and the initiation of muscle contraction through the sliding filament mechanism.