Lac.2
Endocrinology
4th Class
Hypothalamus
@ Location : The hypothalamus is an integral part of the substance of
the brain. The hypothalamus is located below the thalamus, just
above the brain stem. In the terminology of neuroanatomy, it forms
the ventral part of the diencephalon. All vertebrate brains contain a
hypothalamus. In humans, it is roughly the size of an almond.
@ Structure : A small cone-shaped structure, it projects downward,
ending in the pituitary (infundibulum) stalk, a tubular connection to
the gland. It contains a number of small nuclei. The round bony
cavity containing the pituitary gland is called the sella turcica. The
posterior portion of the hypothalamus, called the median eminence,
1
contains many neurosecretory cells. Important adjacent structures
include the mamillary bodies, the third ventricle, and the optic
chiasma.
@ Function : The hypothalamus is a complex region in the brain of
humans, and even small nuclei within the hypothalamus are
involved in many different functions. The paraventricular
nucleus and the supraoptic nucleus
contain oxytocin and vasopressin (also called antidiuretic hormone)
neurons which project to the posterior pituitary, but also contain
neurons that regulate ACTH and TSH secretion from the anterior
pituitary, as well as gastric, maternal behavior, blood
pressure, feeding, immune responses, and temperature.
The hypothalamus is responsible for certain metabolic processes
and other activities of the autonomic nervous system. It synthesizes
and secretes certain neurohormones, often called hypothalamicreleasing hormones, and these in turn stimulate or inhibit the
secretion of pituitary hormones. The hypothalamus controls body
temperature, hunger, thirst, fatigue, and circadian cycles.
2
The hypothalamus, like the rest of the brain, consists of
interconnecting nerve cells ( neurons) with a rich blood supply.
10X
40X
3
@ Secretion :
1. Thyrotropin-releasing hormone(TRH, TRF):
Stimulate thyroid-stimulating hormone (TSH) release from
anterior pituitary.
2. Prolactin-releasing hormone (PRH):
Stimulate prolactin release from anterior pituitary.
3. Dopamine (Prolactin-inhibiting hormone) DA or PIH :
Inhibit prolactin release from anterior pituitary.
4. Growth hormone-releasing hormone(GHRH):
Stimulate Growth hormone (GH) release from anterior
pituitary.
5. Somatostatin (growth hormone-inhibiting hormone) SS,
GHIH, or SRIF: Inhibit Growth hormone (GH) release
from anterior pituitary. Inhibit thyroid-stimulating hormone
(TSH) release from anterior pituitary
6. Gonadotropin-releasing hormone(GnRH or LHRH):
Stimulate follicle-stimulating hormone (FSH) release
fromanterior pituitary .Stimulate luteinizing hormone
(LH) release from anterior pituitary.
7. Corticotropin-releasing hormone(CRH or CRF):
Stimulate adrenocorticotropic hormone (ACTH) release
from anterior pituitary.
8. Oxytocin : Uterine contraction Lactation (letdown reflex).
9. Vasopressin (antidiuretic hormone) ADH or AVP: Increases
water permeability in the distal convoluted tubule and
collecting duct of nephrons, thus promoting water
reabsorption and increasing blood volume.
4
10X
40X
5