There are two main types of cholinergic receptors nicotinic and muscarinic, nicotinic receptors are responsive to nicotine and muscarinic to muscarine as their name state.
Muscarinic receptors, work in the central and peripheral nervous system, therefore they intervene in the nervous connections of the visceral organs or smooth muscle. Meanwhile, the nicotinic receptors work with the central nervous system and intervene in the neuromuscular junction, therefore, the type of receptors on skeletal muscle are nicotinic. This process occurs when nicotine binds the cholinergic receptor the sodium channels open, initiating an action potential in the muscle, and muscle concentration.