Hypothalamus & Pituitary Gland. Hypothalamus and Pituitary Gland. The hypothalamus and pituitary gland form a unit that exerts control over the function of several endocrine glands (thyroid, adrenals, and gonads), as well as a wide range of physiologic activities
The hypothalamus and pituitary gland form a unit that exerts control over the function of several endocrine glands (thyroid, adrenals, and gonads), as well as a wide range of physiologic activities
This unit constitutes an example of neuroendocrinology—brain-endocrine interactions
The pituitary gland (hypophysis) is located in a small depression in the sphenoid bone, the sellaturcica, just beneath the hypothalamus
It is connected to the hypothalamus by a thin stalk called the infundibulum
Most of the cells in the anterior lobe (adenohypophysis) contain secretory granules, although some are only sparsely granulated
Based on their characteristic staining with standard histochemical dyes and immunofluorescent stains, it is possible to identify the cells that secrete each of the pituitary hormones
It once was thought that there was a unique cell type for each of the pituitary hormones, but it is now recognized that some cells may produce more than one hormone
Somatotropes (GH producing cells) are by far the most abundant anterior pituitary cells, and account for at least half the cells
Structurally, prolactin (PRL) is closely related to GH
Oxytocin and AVP are stored in and secreted by the posterior pituitary gland, but are synthesized by the hypothalamus
Regulation of oxytocin secretion showing a positive feedback arrangement.
Increased blood osmolality or decreased blood volume are sensed in the brain or thorax, respectively, and increase vasopressin secretion.
Physiological actions of
In primary target gland hypofunction, such as autoimmune polyglandular syndromes types 1 and 2 (APS 1 and 2), TSH, LH, FSH, or ACTH will be elevated
Low or normal values for these pituitary hormones suggest hypothalamic-pituitary dysfunction