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A major organ of the endocrine system, the anterior pituitary (also called the adenohypophysis or pars anterior) is the glandular, anterior lobe that together with the posterior lobe (posterior pituitary, or the neurohypophysis) makes up the pituitary gland (hypophysis) which, in humans, is located at the base of the brain, protruding off the bottom of the hypothalamus.
The human pituitary gland is oval shaped, about 1 cm in diameter, 0.5–1 gram (0.018–0.035 oz) in weight on average, and about the size of a kidney bean. [2][3] There are two main lobes of the pituitary, an anterior lobe, and a posterior lobe joined and separated by a small intermediate lobe.
The hypophyseal portal system is a system of blood vessels in the microcirculation at the base of the brain, connecting the hypothalamus with the anterior pituitary. Its main function is to quickly transport and exchange hormones between the hypothalamus arcuate nucleus and anterior pituitary gland. The capillaries in the portal system are ...
Other hormone-secreting cells of the pituitary undergo rapid growth in pregnant women as well, which contribute to the gland's enlargement. [10] The anterior pituitary is supplied by a low pressure portal venous system. [15] The anterior pituitary is more commonly affected in Sheehan's syndrome because of the structure of the portal venous system.
The pituitary gland is located at the base of the brain, and intimately connected with the hypothalamus. It consists of two lobes: the posterior pituitary, which consists of nervous tissue branching out of the hypothalamus, and the anterior pituitary, which consists of hormone-producing epithelium.
The arcuate nucleus is an aggregation of neurons in the mediobasal hypothalamus, adjacent to the third ventricle and the median eminence. The arcuate nucleus includes several important and diverse populations of neurons that help mediate different neuroendocrine and physiological functions, including neuroendocrine neurons, centrally projecting ...
The portal system carries the CRH to the anterior lobe of the pituitary, where it stimulates corticotropes to secrete adrenocorticotropic hormone and other biologically-active substances (β-endorphin). ACTH stimulates the synthesis of cortisol, glucocorticoids, mineralocorticoids and DHEA. [7]
Pars tuberalis. Pituitary gland. (Most of the orange region is "pars distalis", but the part at the top is "pars tuberalis".) The pars tuberalis is part of the anterior lobe of the pituitary gland, and wraps the pituitary stalk in a highly vascularized sheath.