Hypothalamus

Hypothalamus

1. Much of the above information is used by the hypothalamus to control secretions of the pituitary hormones. The hypothalamus contains nuclei that synthesize and secrete hormones (via neurons which extend and end) onto their target pituitary gland capillaries.

   • Hypothalamic supraoptic + paraventricular nuclei synthesize and secrete ADH + Oxytocin (via large, magnocellular neurons) directly into
     • POSTERIOR PITUITARY GLAND blood vessels.
       • Thus posterior pituitary gland does not synthesize own hormones. They simply channel the ADH and Oxytocin produced by the Hypothalamus.  
   • Other Hypothalamic nuclei synthesize and secrete Hypothalamic Releasing and Hypothalamic Inhibitory hormones (or factors) into primary capillary plexus (median eminence - see image) which then travel down, via Hypothalamic-hypophysial portal vessels, into
     • ANTERIOR PITUITARY GLAND, and either stimulate or inhibit their synthesis of hormones
       • Also, almost all the blood that enters anterior pituitary first passes through the capillary bed in the lower hypothalamus (median eminence - see "Artery" in image). The blood then flows through the hypothalamic-hypophysial portal blood vessels into the anterior pituitary sinuses.
     • 4 Hypothalamic / Hypophysiotropic (Corticotropin- + Thyrotropin- + Gonadotropin- + Growth Hormone-) Releasing hormones.
       • You can guess what they stimulate release by their names. Example = Thyrotropin releasing hormones stimulates release of thyrotropin etc.
     • 2 Inhibitory hormones: Dopamine (prolactin-inhibiting factor [PIF]) and Somatostatin (GH inhibitory hormone [GHIH]).
       • You can guess what they inhibit by their names: Dopamine inhibits Prolactin. Somatostatin inhibits Growth Hormone.

2. Receives signals from many sources in the nervous system. Thus, it is a collecting center for information concerning the internal well-being of body.

   • Pain, depressing or exciting thought, concentrations of nutrients, electrolytes, water, various hormones in the blood, olfactory stimuli (transmit strong signal components directly and through the amygdaloid nuclei) a portion of all these signals are transmitted into the hypothalamus. 

Imagens e arquivos do mapa