NEET BIOLOGY

Detailed explanation-1: -Stimulation of a muscle fibre by a motor neuron occurs at the neuromuscular junction. the area of contact between a nerve and muscle fibre is called motor end plate. At neuromuscular junction a neuron activates the muscle to contract.

Detailed explanation-2: -Once the muscle fiber is stimulated by the motor neuron, actin, and myosin protein filaments within the skeletal muscle fiber slide past each other to produce a contraction.

Detailed explanation-3: -Motor neurons are covered with ion channels, which open in response to electrical signals from the brain. Once these ion channels are open, a series of cascading reactions allows the signal to reach the skeletal muscle cells, which ultimately results in muscle contraction.

Detailed explanation-4: -In vertebrates, motor neurons release acetylcholine (ACh), a small molecule neurotransmitter, which diffuses across the synaptic cleft and binds to nicotinic acetylcholine receptors (nAChRs) on the cell membrane of the muscle fiber, also known as the sarcolemma.