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Testosterone is the primary male sex hormone and androgen in males. [3] In humans, testosterone plays a key role in the development of male reproductive tissues such as testicles and prostate , as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair .
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 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).
By contrast, the hormones of the anterior pituitary gland (the adenohypophysis) are secreted from endocrine cells that, in mammals, are not directly innervated, yet the secretion of these hormones (adrenocorticotrophic hormone, luteinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone, prolactin, and growth hormone) remains ...
Hormones can be amino acid complexes, steroids, eicosanoids, leukotrienes, or prostaglandins. [3] The endocrine system is contrasted both to exocrine glands, which secrete hormones to the outside of the body, and to the system known as paracrine signalling between cells over a relatively short distance.
The hypothalamus regulates the hormonal output of the anterior pituitary and creates two hormones that it exports to the posterior pituitary for storage and later release. Four of the six anterior pituitary hormones are tropic hormones that regulate the function of other endocrine organs. Most anterior pituitary hormones exhibit a diurnal ...
Plasma levels of DHEA in adult men are 10 to 25 nM, in premenopausal women are 5 to 30 nM, and in postmenopausal women are 2 to 20 nM. [25] Conversely, DHEA-S levels are an order of magnitude higher at 1–10 μM. [25] Levels of DHEA and DHEA-S decline to the lower nanomolar and micromolar ranges in men and women aged 60 to 80 years. [25]
Men experience sexual dysfunction at testosterone levels of below 300 ng/dL, with men that have levels of testosterone of approximately 200 ng/dL often experiencing such problems. [28] Complete loss of testicular testosterone production resulting in testosterone levels within the castrate range (95% decrease, to 15 ng/dL on average) with ...