Final answer:
The receptors located at the motor end plate are acetylcholine (ACh) receptors, which are cholinergic and predominantly nicotinic. They open ion channels causing depolarization and muscle contraction when ACh binds to them.
Step-by-step explanation:
The kind of receptors that are at the surface of the motor end plate are acetylcholine (ACh) receptors. These receptors are located within the motor end-plate of the muscle fiber sarcolemma at the neuromuscular junction (NMJ). When ACh is released from the axon terminal of a motor neuron, it diffuses across the synaptic cleft and binds to these receptors. This binding action subsequently opens ligand-gated ion channels, allowing positively charged ions, particularly Na+, to enter the muscle cell. This influx of ions causes depolarization of the sarcolemma, which initiates muscle contraction. The receptors at the motor end plate are specifically cholinergic receptors, either nicotinic or muscarinic, with the majority being the nicotinic type, which are directly involved in muscle movement as they initiate an action potential leading to muscle contraction.