Thermal Homeostasis
The homeostatic maintenance of the anterior pituitary is crucial to our physiological well being. Increased plasma levels of TSH inducehypothermia through a mechanism involving decreased metabolism and cutaneous vasodilation. Increased levels of LH also result inhypothermia but through a decreased metabolism action. ACTH and prolactin increase metabolism and induce cutaneous vasoconstriction, increased plasma levels also result in hypothermia; FSH also may cause hypothermia if increased beyond homeostatic levels through an increased metabolic mechanism only.
Gonadal Function
Gonadotropes, primarily luteinising hormone (LH) secreted from the anterior pituitary stimulates the ovulation cycle in female mammals, whilst in the males, LH stimulates the synthesis of androgen which drives the ongoing will to mate together with a constant production of sperm.
HPA Axis
Main article Hypothalamic-pituitary-adrenal axis
The anterior pituitary plays a role in stress response. Corticotropin releasing hormone (CRH) from the hypothalamus stimulates ACTHrelease in a cascading effect that ends with the production of glucocorticoids from the adrenal cortex.
35. Posterior pituitary hormones. Their significance for the animal,s body.
Posterior pituitary not itself the site of hormone synthesis, but the site of release of hormones formed in the hypothalamus by neurons whose axons form the hypophyseal-pituitary tract, store the hormones in their terminals, and release them into the blood stream in response to action potentials (neurohormones: compare adrenal medulla). antidiuretic hormone (syn vasopressin) regulates water loss in the kidneys, by increasing water retention; oxytocin stimulates uterine contractions and the ejection of milk from the breasts.
pituitary gland an endocrine gland located at the base of the brain in a small recess of the sphenoid bone called the sella turcica. It is attached by the hypophyseal stalk to the hypothalamus and is divided into an anterior lobe (the adenohypophysis) and a posterior lobe (the neurohypophysis), which differ in embryological function and origin. Called also hypophysis.
The adenohypophysis originates from epithelial tissue. The adenohypophysis secretes six important hormones: growth hormone, thyroid-stimulating hormone or thyrotropin, adrenocorticotropic hormoneor corticotropin, prolactin, follicle-stimulating hormone, and luteinizing hormone. Most of these hormones are tropic hormones, which regulate the growth, development, and proper functioning of other endocrine glands and are of vital importance to the growth, maturation, and reproduction of the individual. Secretion of the anterior pituitary hormones is controlled by releasing and inhibiting hormones produced by the hypothalamus. Information gathered by the nervous system about the well-being of an individual is collected in the hypothalamus and used to control the secretion of hormones by the pituitary gland. The hypothalamic releasing and inhibiting hormones are transported to the pituitary gland by way of the hypothalamic-hypophyseal portal system in which the hypothalamic venules connect with the capillaries of the anterior pituitary.
The neurohypophysis originates from neural tissue; it stores and secretes two hormones, oxytocinand vasopressin (antidiuretic hormone). These hormones are synthesized in the cell bodies of neurons located in the hypothalamus and transported along the axons to the terminals located in the neurohypophysis and are released in response to neural stimulation.
Surgical removal of part or all of the pituitary gland is called hypophysectomy and is usually done for treatment of a pituitary tumor. Because of its influence on the adrenal cortex and other endocrine glands, removal of the pituitary gland has widespread effects on the body.
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