Lecture 23: Hypothalamus

Hypothalamus Functions

Optic chiasm

Preoptic area

ventrolateral preoptic n

Lateral Zone

Medial zone, supraoptic region

Oxytocin & vasopressin (ADH)

part of water balance reflex; respond to changes in blood osmolality

Lesion of the supraoptic or paraventricular nucleus, or shearing of the infundibulum/hypophysial stalk, leads to diabetes insipidus (excessive water consumption and excessive urination)

Oxytocin & vasopressin are also involved in uterine contraction, milk letdown, pair-bonding, and social cognition

Medial zone, tuberal region

Medial zone, mammillary region

Periventricular zone

Periventricular nuclei:

Releasing hormones to anterior pituitary

Small projection to brainstem autonomic nuclei

Descending Efferent Projections from the Hypothalamus

tuberoinfundibular tract

supraopticohyophysial tract

Anterior and Posterior Pituitary Hormones

Pituitary adenomas

Bitemporal hemianopia

Pituitary Gland

Adenohypophysis

Neurohypophysis

Suprarenal Gland Overview

dense CT capsule; supported by reticular CT

outer cortex and inner medulla

adrenocortical insufficiency or Addison’s

disease causes degeneration of the adrenal cortex while typically sparing the medulla

Most common cause is autoimmune

Suprarenal Gland

pheochromocytoma

rare, benign tumors of chromaffin cells

Production of excessive amounts of catecholamines causes potentially life-threatening hypertension and cardiac arrhythmias

Zona Glomerulus: balls of cells

Zone fasciculus: ropes of cells

Zone reticularis: networks of cells

Hypothalamic-Pituitary-Adrenal Axis

Pineal Gland