Functions of the hypothalamus !

Regulation
Exam priority: medium

A small region below the thalamus that keeps the body's settings: temperature, water, hunger, sleep, hormones and the stress response.

Updated 2026-11-01

Also called: Homeostatic control centre, Hypothalamic nuclei

See it in 3D: Hypothalamus · Pituitary gland · Third ventricle · Optic chiasm

Key points

Supraoptic and paraventricular nuclei make ADH and oxytocin; their axons end in the posterior pituitary.
Releasing hormones (TRH, CRH, GnRH, GHRH) and inhibiting ones (somatostatin, dopamine) reach the anterior pituitary through the hypophyseal portal veins.
Temperature: the preoptic/anterior area senses heat and drives heat loss; the posterior area drives heat conservation and production; fever raises the set point through PGE₂.
Appetite: arcuate NPY/AgRP neurons drive hunger, arcuate POMC (α-MSH) neurons drive satiety; leptin inhibits the first and stimulates the second.
The suprachiasmatic nucleus is the master circadian clock, set by retinal light; it controls melatonin release from the pineal gland.
Osmoreceptors in the OVLT, outside the blood–brain barrier, trigger thirst and ADH when plasma osmolality rises by about 1–2%.

What it is

The hypothalamus weighs only a few grams but links the nervous and endocrine systems. It senses blood temperature, osmolality, glucose and hormones directly, receives limbic and brainstem input, and answers through the autonomic system, through releasing hormones sent to the anterior pituitary, and through ADH and oxytocin released from the posterior pituitary. It works as a set-point controller for homeostasis.

Hormone axes and feedback

Hypothalamic–pituitary–adrenal axisLesion None (normal)

Tap a box to see the hormone, or choose a lesion to see the lab pattern.

Stimulates (+)
Inhibits / negative feedback (−)
Level ↑
Level ↓

Tap the hypothalamus and the gland, then try a lesion preset to see how CRH, ACTH and cortisol move.

Regulation

+↑ Plasma osmolality (OVLT osmoreceptors): ADH release and thirst
+Pyrogens (IL-1, IL-6, TNF-α → PGE₂): Raise the thermal set point: fever
+Ghrelin, low leptin: Activate NPY/AgRP neurons: hunger
−Leptin, insulin: Activate POMC neurons and inhibit NPY: satiety
−Cortisol (negative feedback): Inhibits CRH and ACTH
+Light through the retinohypothalamic tract: Resets the suprachiasmatic clock and suppresses melatonin

Hypothalamic regions and their lesions

Region or nucleus	Function	Effect of a lesion
Preoptic / anterior	Heat loss, sleep onset, GnRH	Hyperthermia, insomnia
Posterior	Heat conservation, arousal	Poikilothermia (body temperature drifts with the environment)
Supraoptic and paraventricular	ADH, oxytocin; CRH (paraventricular)	Central diabetes insipidus
Arcuate	Releasing hormones, dopamine, appetite (NPY/POMC)	High prolactin, disturbed appetite
Lateral	Hunger, thirst; orexin for wakefulness	Anorexia, weight loss; orexin loss in narcolepsy
Ventromedial	Satiety	Overeating and obesity
Suprachiasmatic	Circadian rhythm	Disrupted sleep–wake cycle

Clinical notes

Craniopharyngioma in children: pituitary failure, diabetes insipidus, visual field loss and hypothalamic obesity.
SIADH: excess ADH retains water and causes dilutional hyponatremia.
Damage to the hypothalamus or stalk (trauma, surgery) can cause central diabetes insipidus: large volumes of dilute urine and intense thirst.
Narcolepsy is linked to loss of hypothalamic orexin (hypocretin) neurons.

Test yourself

Think of the answer, then tap the question to see it.

Why does destroying the supraoptic and paraventricular nuclei cause polyuria even if the posterior pituitary is intact?

ADH is made in those hypothalamic neurons and only stored and released in the posterior pituitary. Without the cell bodies there is no ADH: central diabetes insipidus.

How does fever differ from heat stroke in hypothalamic terms?

In fever pyrogens raise the set point through PGE₂ and the body actively makes and keeps heat. In heat stroke the set point is normal but heat gain overwhelms heat loss.

Why do the osmoreceptors that control thirst sit in the OVLT?

It is a circumventricular organ with leaky capillaries and no tight blood–brain barrier, so its neurons sense the true osmolality and hormones of plasma.

Why does prolactin rise after pituitary stalk section while the other pituitary hormones fall?

Arcuate dopamine can no longer reach the anterior pituitary through the portal vessels, so lactotrophs lose their tonic inhibition; the other cells lose their releasing hormones.

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See it in 3D

The structures of Durgical's 3D anatomy where it happens.

In Biochemistry

Cortisol

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Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given.

Sources: 17.3 The Pituitary Gland and Hypothalamus (OpenStax (Rice University), 2022); Neuroanatomy, Hypothalamus (StatPearls (NCBI Bookshelf), 2023); 15.3 Central Control (OpenStax (Rice University), 2022); Hall JE. Guyton and Hall Textbook of Medical Physiology, 13th ed. (ch. 59). Reference book used to check facts; its text and figures are not reproduced (Elsevier, 2016).

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Representative model, for educational purposes only.