Chapter 12, Problem 21Q

Summary Introduction

To explain: Why the channel opens and a large net influx of primary sodium (Na⁺) ions happens when acetylcholine binds to the receptor protein of the plasma membrane in muscle cells.

Concept introduction:

Mostly, ligand-gated ion channels are ionotropic receptors, which unlock to permit ions like Na⁺, Ca²⁺, and K⁺ ions to come across the plasma membrane in response to the binding protein that is a chemical messenger. Neurotransmitter is a chemical messenger that binds to the receptors present on the postsynaptic neuron. Acetylcholine, a biologically active substance, utilizes its action on the cell by binding and activating receptors present on the surface of cells. A type of acetylcholine receptor namely nicotinic acetylcholine receptors are the ligand-gated ion channels that are permeable to Na⁺, Ca²⁺, and K⁺ ions.