HYPOTHALAMUS

Hypothalamus Functions Controls/integrates ANS. Raises arterial blood pressure and increases heart rate (posterior). Lowers arterial blood pressure and decreases heart rate (anterior).

Hypothalamus Functions Reception and integration of visceral sensory impulses. Intermediary between nervous and endocrine systems.

Hypothalamus Functions Produces ADH and oxytocin. Involved in psychosomatic disorders. Associated with rage and aggression. Controls normal body temperature.

Hypothalamus Functions Regulates food intake. Maintains extracellular fluid volume. Biorhythm oscillator. Sexual center.

Hypothalamic Nuclei Mammillary bodies: Involved in olfactory reflexes and emotional responses to odors. Relay stations for olfactory neurons to inferior colliculi.

Hypothalamic Nuclei Supraoptic nuclei : Send projections (axons) that release neurohormones into capillaries in the posterior pituitary: Oxytocin Vasopressin

Hypothalamic Nuclei Suprachiasmatic nuclei: Located immediately above optic chiasma. Acts as a master biologic clock, controlling circadian and circannual rhythms. Set to light-dark cycle by a direct retinal projection to the suprachiasmatic nucleus. Anterior nuclei: Caudal continuation of the medial preoptic area.

Hypothalamic Nuclei Paraventricular Medial Division: Projects to the median eminence. Secretes releasing or inhibiting hormones into hypothalamo-hypophyseal portal system: Corticotropin releasing factor. Thyroxin releasing factor. Somatostatin. Dopamine.

Hypothalamic Nuclei Paraventricular Intermediate magnocellular division: Sends projections to the posterior pituitary that release oxtocin and vasopressin Paraventricular lateral division: Receives large number of inputs from brainstem nuclei, other hypothalamic nuclei, limbic system, etc. and projects to a number of sympathetic structures.

Hypothalamic Nuclei Medial preoptic area Much larger in males than in females Contains cells that release gonadotropin- releasing factors to the median eminence into the hypothalamo-hypophyseal portal system. Involved in temperature regulation

HYPOTHALAMUS Tuberal level: Previously considered to be a feeding center and a pleasure center. Lesions here reduce eating behaviors.