Receptor Theory explains how cells communicate with their environment through receptors, which are proteins that bind to specific molecules, known as ligands. This binding triggers a response within the cell, leading to various physiological effects. For example, when a hormone like insulin binds to its receptor, it initiates processes that regulate blood sugar levels. The theory is fundamental in understanding drug action, as many medications work by targeting specific receptors. By mimicking or blocking the action of natural ligands, drugs can modify cellular responses, making Receptor Theory crucial for developing effective treatments for various conditions, including diabetes and hypertension.