Receptor biology is the study of how cells communicate with their environment through specialized proteins called receptors. These receptors are located on the cell surface or within the cell and bind to specific molecules, known as ligands, such as hormones or neurotransmitters. This binding triggers a series of cellular responses, allowing the cell to react to changes in its surroundings. Receptors can be classified into different types, including G protein-coupled receptors and ion channel receptors. Each type has a unique mechanism of action and plays a crucial role in various physiological processes, such as signal transduction, immune response, and neurotransmission. Understanding receptor biology is essential for developing targeted therapies in medicine.