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The pituitary gland or hypophysis is an endocrine gland in vertebrates. In humans , the pituitary gland 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 .
Hypothalamic interaction with the posterior and anterior pituitary glands. The hypothalamus produces the hormones oxytocin and vasopressin in its endocrine cells (left). These are released at nerve endings in the posterior pituitary gland and then secreted into the systemic circulation.
One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus is located below the thalamus and is part of the limbic system. [1] It forms the basal part of the diencephalon. All vertebrate brains contain a hypothalamus. [2] In humans, it is about the size of an almond. [3]
The tuberoinfundibular pathway transmits dopamine from the hypothalamus to the pituitary gland. This neural circuit plays a pivotal role in the regulation of hormonal balance and, specifically, in modulating the secretion of prolactin from the pituitary gland, which is responsible for breast milk production in females.
HPG regulation in males, with the inhibin/activin system playing a similar role on GnRH-producing cells. The hypothalamus is located in the brain and secretes GnRH. [1] GnRH travels down the anterior portion of the pituitary via the hypophyseal portal system and binds to receptors on the secretory cells of the adenohypophysis. [2]
The posterior pituitary is not glandular as is the anterior pituitary. Instead, it is largely a collection of axonal projections from the hypothalamus that terminate behind the anterior pituitary, and serve as a site for the secretion of neurohypophysial hormones ( oxytocin and vasopressin ) directly into the blood. [ 2 ]
These hormones are prolactin, growth hormone, TSH, adrenocorticotropic hormone, FSH and LH. They are all released by anterior pituitary. Some have targets in glands and some with direct function. Anterior pituitary is an amalgam of hormone producing glandular cells. There are conditions related to the limbic system which regulate the hormone ...
Parvocellular vasopressin cells, which project to many points in the hypothalamus and limbic system, as well as to the brainstem and spinal cord (these are involved in blood pressure and temperature regulation), and brown fat thermogenesis. Parvocellular CRH neurons, which are thought to be involved in stress-related behaviors.