Hormones of the Hypothalamus and Pituitary Gland

Hormones of the Hypothalamus and Pituitary Gland
The pituitary gland, or hypophysis, is a small gland (0.5 g in humans) lying in a well-protected position between the roof of the mouth and floor of the brain (Figure 36-5). It is a two-part gland having a double embryological origin. The anterior pituitary (adenohypophysis) is derived embryologically from the roof of the mouth. The posterior pituitary (neurohypophysis) arises from a ventral portion of the brain, the hypothalamus, and is connected to it by a stalk, the infundibulum. Although the anterior pituitary lacks any anatomical connection to the brain, it is functionally connected to it by a special portal circulatory system. A portal circulation is one that delivers blood from one capillary bed to another (Figures 36-5 and 36-6). In this case, the portal circulation provides a link between neurosecretory cells of the hypothalamus and anterior pituitary gland.

chemical coordination, mechanisms of hormone action, membrane bound receptors and the second messenger concept, nuclear receptors, invertebrate hormones, vertebrate endocrine glands and hormones, hormones of the hypothalamus and pituitary gland, hypothalamus and neurosecretion, anterior pituitary, posterior pituitary, pineal gland, brain neuropeptides, prostaglandins and cytokines, hormones of metabolism, thyroid hormones, hormonal regulation of calcium metabolism, hormones of the adrenal cortex, hormones of the adrenal medulla, insulin and glucagon from islet cells of the pancreas, growth hormone and metabolism, the newest hormone leptin
Figure 36-5 Human hypothalamus and pituitary gland. The posterior lobe is connected
directly to the hypothalamus by neurosecretory fibers. The anterior lobe is indirectly
connected to the hypothalamus by a portal circulation (shown in red)
beginning in the base of the hypothalamus and ending in the anterior pituitary.