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The anterior pituitary (also called the adenohypophysis or pars anterior) is a major organ of the endocrine system.The anterior pituitary is the glandular, anterior lobe that together with the (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 pituitary gland (or hypophysis) is an endocrine gland about the size of a pea and weighing 0.5 grams (0.018 oz) in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica) covered by a dural fold (diaphragma sellae).
The anterior pituitary synthesizes and secretes hormones. All releasing hormones (-RH) referred to can also be referred to as releasing factors (-RF). Somatotropes: Growth hormone (GH), also known as somatotropin, is released under the influence of hypothalamic growth hormone-releasing hormone (GHRH), and is inhibited by hypothalamic somatostatin.
The hypothalamus controls the anterior pituitary's hormone secretion by sending releasing factors, called tropic hormones, down the hypothalamo-hypophysial portal system. [3] For example, thyrotropin-releasing hormone released by the hypothalamus in to the portal system stimulates the secretion of thyroid-stimulating hormone by the anterior ...
A neurohormone is any hormone produced and released by neuroendocrine cells (also called neurosecretory cells) into the blood. [1] [2] By definition of being hormones, they are secreted into the circulation for systemic effect, but they can also have a role of neurotransmitter or other roles such as autocrine (self) or paracrine (local) messenger.
Proper hormone secretion is crucial for the growth of the developing fetus. In order to allow a controlled hormone secretion in the developing organs of the fetus, stimulating hormones must be exchanged in the regulating structures in the brain in early stages of the development.
Insufficient secretion of vasopressin underlies diabetes insipidus, a condition in which the body loses the capacity to concentrate urine. Affected individuals excrete as much as 20 liters of dilute urine per day. Oversecretion of vasopressin causes the syndrome of inappropriate antidiuretic hormone (SIADH).
As more became known about neurosecretory cells, the difference between the actions of nerve communication and endocrine hormone release become less clear. Like the average neuron, these cells conduct electrical impulses along the axon but unlike these neurons, neurosecretion produces neurohormones that are released into the body’s circulation.