Section II. THE PITUITARY BODY
a. Location. The pituitary body is a small pea-sized and pea- shaped
structure. It is attached to the base of the brain in the region of the hypothalamus (see
it is housed within
of the bony floor
of the cranial
cavity. This hollow is called the sella turcica ("Turk's saddle").
b. Major Subdivisions. The pituitary body is actually two glands-- the poste-
rior pituitary gland and the anterior pituitary gland. Initially separate, these glands join
together during development of the embryo.
POSTERIOR PITUITARY GLAND
The posterior pituitary gland is the portion which comes from and retains a direct
connection with the base of the brain. The hormones of the posterior pituitary gland are
actually produced in the hypothalamus of the brain. From the hypothalamus, the
hormones are delivered to the posterior pituitary gland, where they are released into the
bloodstream. At present, we recognize two hormones of the posterior pituitary gland.
a. ADH (Antidiuretic Hormone). ADH is involved with the resorption or
salvaging of water within the kidneys. ADH is produced under thirst conditions.
b. Oxytocin. Oxytocin is concerned with contractions of smooth muscle in
the uterus and with milk secretion.
ANTERIOR PITUITARY GLAND
a. The anterior pituitary gland originates from the roof of the embryo's mouth. It
then "attaches" itself to the posterior pituitary gland.
b. The anterior pituitary gland is indirectly connected to the hypothalamus by
means of a venous portal system. By "portal," we mean that the veins carry substances
from the capillaries at one point to the capillaries at another point (hypothalamus to the
anterior pituitary gland).
c. In the hypothalamus, certain chemicals known as releasing factors are
produced. These are carried by the portal system to the anterior pituitary gland. Here,
they stimulate the cells of the anterior pituitary gland to secrete their specific hormones.
d. The anterior pituitary gland produces many hormones. In general, they
stimulate the target organs to develop or produce their own products. This stimulating
effect is referred to as trophic.