hormonaux

Hormonaux are chemical messengers produced by specialized cells and released into body fluids to regulate physiological processes. They travel through the bloodstream or act locally and influence the activity of distant or nearby target cells that carry specific receptors. Hormones can be broadly classified by their chemical nature as peptide or protein hormones, steroid hormones derived from cholesterol, and amine hormones derived from amino acids such as tyrosine or tryptophan. Most hormones are secreted by glands of the endocrine system, including the hypothalamus, pituitary, thyroid, parathyroid, adrenal glands, pancreas, gonads, and pineal gland, but many tissues also produce hormones that exert local effects (local or paracrine signaling).

Mechanism: hormone binding to receptors triggers signaling cascades that modulate enzyme activity, ion channels, gene expression, or cell growth. Some receptors are on the cell surface; others are intracellular and affect transcription directly.

Functions: hormones regulate metabolism, growth, development, reproduction, water and electrolyte balance, immune function, and responses to stress.

Regulation: Hormone levels are controlled by feedback loops, such as negative feedback; circadian and ultradian rhythms; interaction with the nervous system; clearance by liver and kidneys.

Clinical relevance: Abnormal hormone production or action leads to endocrine disorders (diabetes mellitus, thyroid disease, adrenal disorders). Therapeutic use includes hormone replacement (insulin, thyroid hormone, corticosteroids, estrogen/progestin, testosterone), and drugs that imitate or block hormonal action. Exposure to environmental disruptors can alter endocrine signaling.