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Feed back control. HBS3A. Simple negative feedback systems. Negative feedback with cascading hormones. Negative feedback of metabolic rate. Low metabolic rate Low blood thyroxine level Increased energy requirement. 5 High metabolic rate High blood thyroxine level
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Feed back control HBS3A
Negative feedback of metabolic rate Low metabolic rate Low blood thyroxine level Increased energy requirement 5 High metabolic rate High blood thyroxine level Decreased energy requirement 4 Releases more thyroxine Releases less thyroxine 1 6 Hypothalamus Thyroid gland Thyroid gland Releases less TSH releasing factor 2 Releases more TSH releasing factor Releases less TSH 3 Releases more TSH Anterior lobe of pituitary gland
Negative feedback of metabolic rate • In the hypothalamus receptors • In response to this • Thyroid Stimulating Hormone (TSH) is carried where it causes an • Increased thyroxine causes thus increasing • This increased energy release causes an increase in t________ and is detected by the h______________ • Negative feedback is achieved by Factors like metabolic rate can only fluctuate within narrow limits because Other factors under negative feedback control include
Negative feedback of metabolic rate 1. In the hypothalamus receptors detect changes in chemical composition of blood (decreased thyroxine) and secretes more TSH releasing factor 2. In response to this the anterior pituitary increases secretion of TSH 3. Thyroid Stimulating Hormone (TSH) is carried to the thyroid, where it causes an increase in thyroxine secretion 4. Increased thyroxine causes an increase in metabolic rate, thus increasing energy production 5. This increased energy release is seen as increased body temperature and detected by the hypothalamus 6, Negative feedback is achieved by hypothalamus reducing TSHRF less TSH less thyroxine Factors like metabolic rate can only fluctuate within narrow limits because they are under similar negative feedback control Other factors under negative feedback control include blood sugar, pH, blood gases, water & salt balance, etc
Control of ovarian cycle • The hypothalamus controls release of g___________ from anterior pituitary by • Release of F__________ S____________ H_________ (FSH) from a__________ p___________ causes the 3. The developing follicle releases _________, which acts on the uterus to ____________ 4. High levels of oestrogen stimulate hypothalamus to release ____________________, which causes anterior pituitary to decrease secretion of ______________ and increase secretion of ____________. 5. L____________ H_________ (LH) acts on the____________ to induce ____________, and the development of the c_____________ l_________________
Control of ovarian cycle 6. The corpus luteum secretes __________ and ___________, which act on the uterus to _________________ High levels of oestrogen and progesterone inhibit the release of ________ and _______ from the hypothalamus. 7. If no pregnancy occurs, the corpus luteum __________, and levels of oestrogen and progesterone ________. This causes the uterine lining to ______ (a process called m_____________), and the hypothalamus to release ________, thus starting a new cycle.
Control of ovarian cycle 1. The hypothalamus controls release of gonadotrophins from anterior pituitary by the use of releasing and inhibiting factors 2. Release of Follicle Stimulating Hormone (FSH) from anterior pituitary causes the development of a follicle in the ovary 3. The developing follicle releases oestrogen, which acts on the uterus to repair the endometrium 4. High levels of oestrogen stimulate hypothalamus to release FSH IF & LH RF, which causes anterior pituitary to decrease secretion of FSH and increase secretion of LH. 5. Luteinising Hormone (LH) acts on the follicle to induce ovulation, and the development of the corpus luteum. 6. The corpus luteum secretes oestrogen and progesterone, which act on the uterus to prepare it for pregnancy (increased size and number of glands & blood vessels). High levels of oestrogen and progesterone inhibit the release of FSH RF and LH RF from the hypothalamus. 7. If no pregnancy occurs, the corpus luteum degenerates, and levels of oestrogen and progesterone fall. This causes the uterine lining to shed (a process called menstruation), and the hypothalamus to release FSH RF, thus starting a new cycle.
Control of female reproduction The cycle first starts in young women at p________, when they start menstruating, (between the ages of ___ and ____) and starts to slow down and finally stop at m_____________ (between the ages of ___ and ____). Women can control their fertility or their cycle by use of h________ c____________. Hormonal contraception includes and is used for These act by Some problems or side effects include Reproductive hormones can also be used in the treatment of female infertility. Uses include
Control of female reproduction The cycle first starts in young women at puberty, when they start menstruating, (between the ages of 11 and 13) and starts to slow down and finally stop at menopause (between the ages of 45 and 55). Women can control their fertility or their cycle by use of hormonal contraception. Hormonal contraception includes oestrogens and progesterones and is used for prevention of pregnancy and control of the cycle These act by inhibiting the release of FSH and LH, thus preventing ovulation. They also alter the lining of the uterus, thus making it less likely for implantation to occur, and changes the cervical mucus so it is thick and sticky, thus preventing sperm entering. Some problems or side effects include acne, blood clots (especially in the veins), increase in blood pressure, headaches, changes in menstruation, mood changes, nausea and vomiting, period pain, vaginal discharge, weight gain, and a change in sexual desire, increased risk of osteoporosis and it can take a while to start ovulating afterwards, leading to problems with fertility. Reproductive hormones can also be used in the treatment of female infertility. Uses include increasing ovulation for IVF and controlling irregularities in ovarian cycle.
Menopause and treatments The changes in hormone levels seen during and after menopause include Some problems seen due to these changes include Women suffering from the changes of menopause can be treated with HRT (H__________ R___________ T_____________). This involves Some problems with HRT include
Menopause and treatments The changes in hormone levels seen during and after menopause include decrease in oestrogen and progesterone Some problems seen due to these changes include hot flushes and night sweats, itching sensations, headaches, thinning and dryness of the vagina, aches and pains, frequent urination, reduced sex drive, tiredness and irritability, disturbances in mood and depression, sleeping difficulties Women suffering from the changes of menopause can be treated with HRT (Hormone Replacement Therapy. This involves taking oestrogen and progesterone supplements as pills, patches, gels, implants or sprays Some problems with HRT include increased risks of breast cancer, cardiovascular disease and thrombosis
Control of male reproduction Males also produce LH and FSH, starting at puberty (between the ages of ___ and ____) but the levels fluctuate less than in females. These hormones are responsible for regulating production of s_______________ and t_______________. Hormonal contraception in males has ________ been as successful as in females. Reproductive hormones can also be used in the treatment of male infertility. Uses include Males also have a reduction in reproductive hormones as they age, but continue to produce hormones until the end of their lives.
Control of male reproduction Males also produce LH and FSH, starting at puberty (between the ages of 13 and 15) but the levels fluctuate less than in females. These hormones are responsible for regulating production of sperm and testosterone. Hormonal contraception in males has not been as successful as in females. Reproductive hormones can also be used in the treatment of male infertility. Uses include increasing gonadotrophin levels to increase sperm count. Males also have a reduction in reproductive hormones as they age, but continue to produce hormones until the end of their lives.
