What part of the sarcolemma contains acetylcholine receptors?
A. any part of the sarcolemma
B. part adjacent to another muscle cell
C. motor end plate
D. end of the muscle fiber
The Neuromuscular Junction
The neuromuscular junction is a highly specialized synapse between the terminal end of a motor neuron and a muscle fiber. This synapse plays a vital role in the function of skeletal muscle, as it is responsible for transmitting the signal between the nervous system and muscle, resulting in muscle fiber action. At the neuromuscular junction, the motor neuron transmits this signal by releasing acetylcholine.
A number of steps must occur in order for successful muscle contraction:
- The action potential reaches the terminal end of a motor neuron.
- Voltage-gated calcium channels open, allowing calcium to rush into the axon terminal.
- Neurotransmitter vesicles fuse to the presynaptic membrane, and acetylcholine is released into the synaptic cleft.
- Acetylcholine binds to receptors on the sarcolemma.
- Sodium, potassium, and other cations begin to flow across the cell membrane, generating an action potential within the muscle fiber.
- The muscle contracts.