Which part of the sarcolemma contains acetylcholine receptors?

The part of the sarcolemma that contains acetylcholine receptors is referred to as the motor end plate. This specialized region is located at the neuromuscular junction, where the motor neuron and the muscle fiber communicate. When an action potential reaches the neuromuscular junction, it triggers the release of acetylcholine from the synaptic vesicles into the synaptic cleft. The acetylcholine then binds to its receptors on the motor end plate, which leads to the depolarization of the muscle fiber's membrane and initiates muscle contraction.

The design of the motor end plate includes numerous folds and infoldings that increase the surface area, thereby maximizing the number of acetylcholine receptors present. This characteristic helps ensure that a sufficient amount of acetylcholine can effectively trigger muscle contraction.

Understanding this specialized interaction at the neuromuscular junction and the role of the motor end plate is crucial for grasping how nerve impulses result in muscle contractions, making it an essential concept in the study of muscle physiology.