For more information about glands and hormones, as well as educational resources, visit the Society for Endocrinology's 'You and Your Hormones' website. Information is vital for pituitary patients and we can't do this without you. Your download is complete. You are here: Home Information Hormones Your hormones Hormones are chemicals which circulate in the blood stream and spread around the body to carry messages or signals to different parts of the body.
Hormones produced by the pituitary gland The two sections of the pituitary gland produce a number of different hormones which act on different target glands or cells. ACTH is also known as corticotrophin.
TSH Thyroid Stimulates the thyroid gland to secrete its own hormone, which is called thyroxine. TSH is also known as thyrotrophin. Stimulates the ovaries to produce oestrogen and progesterone and the testes to produce testosterone and sperm. LH and FSH are known collectively as gonadotrophins. PRL Breasts Stimulates the breasts to produce milk. This hormone is secreted in large amounts during pregnancy and breast feeding, but is present at all times in both men and women.
GH All cells in the body Stimulates growth and repair. Metabolism; heart rate and output; response to stress and exercise. Cortisol Corticosterone. Blood vessel smooth muscle Adrenal cortex. Blood pressure Aldosterone secretion. Reproductive development; also has effects on oestrus behaviour. Progesterone from corpus luteum. Prostaglandin PGF2? Breakdown of corpus luteum luteolysis. The majority of testosterone produced in the ovary is converted to the principle female sex hormone, oestradiol.
The regulation of testosterone production is tightly controlled to maintain normal levels in blood, although levels are usually highest in the morning and fall after that. The hypothalamus and the pituitary gland are important in controlling the amount of testosterone produced by the testes. In response to gonadotrophin-releasing hormone from the hypothalamus, the pituitary gland produces luteinising hormone which travels in the bloodstream to the gonads and stimulates the production and release of testosterone.
As blood levels of testosterone increase, this feeds back to suppress the production of gonadotrophin-releasing hormone from the hypothalamus which, in turn, suppresses production of luteinising hormone by the pituitary gland.
Levels of testosterone begin to fall as a result, so negative feedback decreases and the hypothalamus resumes secretion of gonadotrophin-releasing hormone. The effect excess testosterone has on the body depends on both age and sex. It is unlikely that adult men will develop a disorder in which they produce too much testosterone and it is often difficult to spot that an adult male has too much testosterone. In both males and females, too much testosterone can lead to precocious puberty and result in infertility.
In women, high blood levels of testosterone may also be an indicator of polycystic ovary syndrome. Women with this condition may notice increased acne , body and facial hair called hirsutism , balding at the front of the hairline, increased muscle bulk and a deepening voice. There are also several conditions that cause the body to produce too much testosterone. The luteal and secretory phases refer to changes in the ruptured follicle. The cells in the follicle undergo physical changes, producing a structure called a corpus luteum, which produces estrogen and progesterone.
The progesterone facilitates the regrowth of the uterine lining and inhibits the release of further FSH and LH. The uterus is again being prepared to accept a fertilized egg, should it occur during this cycle.
The level of estrogen produced by the corpus luteum increases to a steady level for the next few days. If no fertilized egg is implanted into the uterus, the corpus luteum degenerates and the levels of estrogen and progesterone decrease. The endometrium begins to degenerate as the progesterone levels drop, initiating the next menstrual cycle. Stages of the menstrual cycle : Rising and falling hormone levels result in progression of the ovarian and menstrual cycles.
As women approach their mids to mids, their ovaries begin to lose their sensitivity to FSH and LH. Menstrual periods become less frequent and finally cease; this process is known as menopause.
There are still eggs and potential follicles on the ovaries, but without the stimulation of FSH and LH, they will not produce a viable egg to be released. The outcome of this is the inability to have children. Various symptoms are associated with menopause, including hot flashes, heavy sweating, headaches, some hair loss, muscle pain, vaginal dryness, insomnia, depression, weight gain, and mood swings.
Estrogen is involved in calcium metabolism and, without it, blood levels of calcium decrease. To replenish the blood, calcium is lost from bone, which may decrease the bone density and lead to osteoporosis.
Supplementation of estrogen in the form of hormone replacement therapy HRT can prevent bone loss, but the therapy can have negative side effects, such as an increased risk of stroke or heart attack, blood clots, breast cancer, ovarian cancer, endometrial cancer, gall bladder disease, and, possibly, dementia.
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