Question

very briefly write short notes on hormones

Answer 1

- Definition: Hormones are chemical messengers secreted by endocrine cells that travel (blood or locally) to regulate physiology and behavior.
- Types by origin: Endocrine (bloodstream), paracrine (local), autocrine (self), neuroendocrine (neurons releasing hormones).
- Chemical classes: Peptides/proteins, steroid hormones (cholesterol-derived), and amine/thyroid hormones (derived from amino acids).
- Receptors & action: Peptides/amines bind cell-surface receptors and use second messengers; steroids/thyroids cross membranes and act on nuclear receptors to change gene transcription.
- Transport & half-life: Water-soluble hormones circulate freely with short half-lives; lipid-soluble hormones bind carrier proteins and have longer half-lives.
- Regulation: Secretion controlled by negative (and sometimes positive) feedback loops, neural input, and humoral signals (e.g., blood glucose, ions).
- Major glands & examples: Hypothalamus-pituitary (TRH/TSH, ACTH), thyroid (T3/T4), adrenal (cortisol, aldosterone, adrenaline), pancreas (insulin, glucagon), gonads (estrogen, testosterone).
- Key functions: Metabolism (insulin, thyroid), stress response (cortisol, adrenaline), fluid/electrolyte balance (aldosterone, ADH), growth/reproduction (GH, sex steroids).
- Clinical relevance: Hormone excess/deficiency causes disease (e.g., diabetes, hypothyroidism/hyperthyroidism, Cushing’s, Addison’s); hormones are diagnostic markers and therapeutic agents.
- Measurement: Blood/urine hormone levels, stimulation/suppression tests, and receptor/genetic studies guide diagnosis and treatment.