MUSCLE PHYSIOLOGY

Detailed explanation-1: -The channels are opened, or gated, by the binding of a neurotransmitter to an orthosteric site(s) that triggers a conformational change that results in the conducting state. Modulation of gating can occur by the binding of endogenous, or exogenous, modulators to allosteric sites.

Detailed explanation-2: -The acetylcholine can bind onto the boundary regions of the alpha-delta and alpha-gamma domains. In its closed state, the acetylcholine receptor contains large and hydrophobic amino acids within the inner cavity and this prevents the movement of polar ions across the membrane.

Detailed explanation-3: -If these receptors are ligand-gated ion channels, a resulting conformational change opens the ion channels, which leads to a flow of ions across the cell membrane. This, in turn, results in either a depolarization, for an excitatory receptor response, or a hyperpolarization, for an inhibitory response.

Detailed explanation-4: -The best-studied ligand-gated ion channel is the nicotinic ACh receptor (nAChR), so named because the CNS stimulant, nicotine, also binds to these receptors.

Detailed explanation-5: -The acetylcholine binds to the nicotinic receptors concentrated on the motor end plate, a specialized area of the muscle fibre’s post-synaptic membrane. This binding causes the nicotinic receptor channels to open and let sodium ions enter the muscle fibre.