Answer:
Cation ligand-gated channels
Explanation:
At the neuromuscular junction, the arrival of nerve impulse triggers the release of chemical signals called neurotransmitters in the cleft. Binding of these chemical signals to the receptor present on the motor endplate results in the opening of a ligand-gated cation ion channel. These channels are present in the receptor. Opening of ion channels allow cations, specifically Na+, to flow across the membrane. The entry of cations makes the inside of the muscle fiber more positively charged and triggers a muscle action potential.
