Receptor:A protein molecule on the cell surface or within cells that binds to specific molecules like hormones or neurotransmitters, initiating a physiological response.
Signal Transduction: The process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most often involving the binding of ligands to receptors.
Cell Membrane:The thin, flexible barrier that surrounds all cells; it controls what enters and leaves the cell and facilitates communication between cells through receptor-ligand interactions