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.