Endocrine Physiology

^{[1] [4] [11] [13] [10] [5] [20]}

A 62-year-old with pneumonia is in septic shock: noradrenaline requirements keep climbing despite fluids — the hypotensive, fluid- and vasopressor-poorly-responsive septic patient in whom the consensus says to suspect critical illness-related corticosteroid insufficiency.^[11] By day 2 his glucose is high and his thyroid panel shows a low T3 with a normal TSH. Each finding maps onto an axis below.^[10]

The hypothalamus and pituitary

The release of anterior pituitary hormones is regulated by hypothalamic releasing or inhibitory hormones, synthesised in neurons around the third ventricle and released into the hypophyseal portal blood, which carries them to the anterior pituitary.^[1] The posterior pituitary is neural in origin and, unlike the anterior pituitary, is connected directly to the hypothalamus by the hypothalamohypophyseal nerve tract; its hormones travel with neurophysin proteins along the axons to nerve terminals in the posterior pituitary.^[1]

^{[1] [5]}

Prolactin is the exception to product feedback: the anterior pituitary synthesises and secretes it under dopamine-mediated hypothalamic regulation, and dopamine antagonists (antipsychotics), TRH and oestrogen stimulate it.^[4]

References27ShowHide

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