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10-5. 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.

e. Of the many hormones produced by the anterior pituitary gland, we will examine:

(1) Somatotrophic hormone (growth hormone). The target organs of this hormone are the growing structures of the body. This hormone influences such structures to grow.

(2) ACTH (adrenocorticotrophic hormone). This hormone of the anterior pituitary gland stimulates the cortex of the suprarenal (adrenal) gland to produce its hormones. We will later see that the hormones of the suprarenal cortex are involved with anti-inflammatory reactions of the body.

(3) Thyrotropin (TSH). This hormone stimulates the thyroid gland to produce its hormones.

(4) Luteinizing hormone (LH). LH stimulates ovulation and luteinization of ovarian follicles in females and promotes testosterone production in males.

(5) Follicle-stimulating hormone (FSH). FSH stimulates ovarian follicle growth in females and stimulates spermatogenesis in males. (6) Prolactin. Prolactin stimulates milk production and maternal behavior in females.

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