GLOSSARY

The hypothalamus is a small region of the diencephalon (about 4 grams, under 1 percent of brain weight) below the thalamus and above the pituitary; it is the main bridge between the nervous and endocrine systems and the body’s homeostatic control centre.

Main Functions

• Pituitary control: secreting releasing and inhibiting hormones into the anterior pituitary portal system and producing ADH and oxytocin for the posterior pituitary.
• Temperature regulation: the body’s thermostat (the preoptic area).
• Hunger and satiety: the arcuate nucleus (appetite-stimulating NPY/AgRP and appetite-suppressing POMC neurons), responding to leptin, ghrelin, and insulin.
• Thirst and water balance: osmoreceptors.
• Circadian rhythm: the suprachiasmatic nucleus (SCN), the body’s “master clock”.
• Control of the autonomic nervous system and emotional responses (with the limbic system).

Important Nuclei