Ligand-receptor interaction is a fundamental biological process where a ligand, such as a hormone or neurotransmitter, binds to a specific receptor on the surface of a cell. This binding triggers a series of cellular responses, allowing the cell to communicate and respond to changes in its environment. The specificity of this interaction is crucial for maintaining proper physiological functions. Once the ligand binds to the receptor, it can activate or inhibit various signaling pathways within the cell. This can lead to changes in gene expression, enzyme activity, or ion channel permeability, ultimately influencing the cell's behavior and function. Understanding these interactions is essential for developing targeted therapies in medicine.