polypeptidhormon

Polypeptide hormones are a class of hormones that are composed of chains of amino acids. These hormones play crucial roles in regulating a wide range of physiological processes in the body, including metabolism, growth, reproduction, and stress response. Unlike steroid hormones, which are derived from cholesterol, polypeptide hormones are synthesized from amino acids and stored in secretory vesicles within endocrine cells.

The synthesis of polypeptide hormones involves transcription and translation, similar to the production of other proteins. Once synthesized, they are often processed into their active forms through cleavage and modification. They are then released into the bloodstream in response to specific stimuli. Their action is mediated by binding to specific receptor proteins on the surface of target cells. This binding initiates a cascade of intracellular events that ultimately lead to a specific cellular response, such as changes in enzyme activity or gene expression.

Examples of important polypeptide hormones include insulin, which regulates blood glucose levels; growth hormone, which promotes growth and cell reproduction; glucagon, which counteracts the action of insulin by raising blood glucose; and antidiuretic hormone (ADH), which regulates water balance. The diverse functions of polypeptide hormones highlight their essential role in maintaining homeostasis and overall health. Dysregulation in their production or signaling can lead to various endocrine disorders.