Cue Column | Notes Column

What is the endocrine system? | The endocrine system comprises ductless glands that secrete hormones directly into the bloodstream to regulate physiology. It works slower but produces longer-lasting effects than the nervous system.

Master hierarchy | Hypothalamus (master coordinator) → Anterior Pituitary (master gland) → Peripheral glands (thyroid, adrenal, gonads)

Hypothalamus outputs | Releasing hormones: GnRH, CRH, TRH, GHRH — stimulate anterior pituitary. Inhibiting hormones: Somatostatin (blocks GH+TSH), PIF/Dopamine (blocks prolactin).

Anterior pituitary (FLAT PG) | FSH, LH, ACTH, TSH, Prolactin, GH. All produced by glandular (epithelial) cells.

Posterior pituitary | Stores and releases ADH and oxytocin — synthesised in hypothalamic nuclei (supraoptic = ADH; paraventricular = oxytocin). Critical NEET trap.

Peripheral glands | Thyroid (T3, T4, calcitonin), Parathyroid (PTH), Adrenal cortex (aldosterone, cortisol, androgens), Adrenal medulla (adrenaline, noradrenaline), Pancreas (insulin, glucagon, somatostatin), Pineal (melatonin), Thymus (thymosins), Gonads (oestrogen, progesterone, testosterone).

Regulation mechanism | Negative feedback: rising end-hormone inhibits hypothalamic releasing hormone and pituitary tropic hormone. Exception: mid-cycle oestrogen → positive feedback → LH surge.

Summary (bottom section):

The endocrine system is a hierarchical chemical communication network. The hypothalamus-pituitary axis controls most peripheral glands via releasing hormones (anterior pituitary) or direct neural axons (posterior pituitary). Negative feedback is the universal regulatory principle. NEET tests: posterior pituitary synthesis site, FLAT PG mnemonic, gland-hormone-function mapping.