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1 2 Think about… 4.1 Hormonal control of the menstrual cycle 4.2 Use of hormones Recall ‘Think about…’ Summary concept map.

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Presentation on theme: "1 2 Think about… 4.1 Hormonal control of the menstrual cycle 4.2 Use of hormones Recall ‘Think about…’ Summary concept map."— Presentation transcript:

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3 2 Think about… 4.1 Hormonal control of the menstrual cycle 4.2 Use of hormones Recall ‘Think about…’ Summary concept map

4 3 The performance of female athletes may be affected by their physiological conditions before or during menstruation.

5 4 Some athletes may take drugs to prevent menstruation from occurring during sports games.

6 5 The drugs contain hormones which are similar to those naturally produced in the female body. What are the hormones involved? How do the drugs prevent menstruation? Can menstruation be resumed later?

7 6 4.1 Hormonal control of the menstrual cycle Let’s revise the menstrual cycle first.

8 7 The menstrual cycle Cycle repeats until meno…

9 8 The maturation and release of egg cells from the ovary are synchronized with changes in the uterus

10 9 The Ovarian Cycle In the ovarian cycle –Hormones stimulate follicle growth, which results in ovulation Following ovulation –The follicular tissue left behind transforms into the corpus luteum Three phases: follicular --- ovulation --- luteal Three phases: follicular --- ovulation --- luteal (1-14) (14) (14-28) (1-14) (14) (14-28)

11 10 The Uterine Cycle Menstrual -- proliferative ------- secretory Three phases : Menstrual -- proliferative ------- secretory (1-6) (6-14) (14-28) (1-6) (6-14) (14-28)

12 11 Day 1 to 5 of the menstrual cycle 4.1 Hormonal control of the menstrual cycle uterine lining breaks down follicle begins to develop

13 12 Day 5 to 14 of the menstrual cycle 4.1 Hormonal control of the menstrual cycle uterine lining begins to thicken follicle becomes mature

14 13 Day 14 of the menstrual cycle 4.1 Hormonal control of the menstrual cycle uterine lining becomes very thick ovulation occurs

15 14 Day 14 to 28 of the menstrual cycle 4.1 Hormonal control of the menstrual cycle uterine lining remains thick ovum is moved along the oviduct

16 15 What are the hormones involved? 4.1 Hormonal control of the menstrual cycle

17 16 4.1 Hormonal control of the menstrual cycle events synchronized by the interaction of four hormones: follicle stimulating hormone (FSH) pituitary gland luteinising hormone (LH)

18 17 4.1 Hormonal control of the menstrual cycle oestrogen follicle yellow body events synchronized by the interaction of four hormones:

19 18 4.1 Hormonal control of the menstrual cycle progesterone yellow body events synchronized by the interaction of four hormones:

20 19 4.1 Hormonal control of the menstrual cycle How do the hormones interact? the hormones interact by feedback mechanisms

21 20 4.1 Hormonal control of the menstrual cycle pituitary gland  FSH stimulation ovary

22 21 4.1 Hormonal control of the menstrual cycle pituitary gland  follicle develops ovary

23 22 4.1 Hormonal control of the menstrual cycle pituitary gland  Above a certain level, oestrogen stimulates FSH and LH secretion ovary

24 23 4.1 Hormonal control of the menstrual cycle pituitary gland  LH ovary LH stimulates oestrogen secretion and oestrogen stimulates FSH and LH secretion …. A positive feedback effect A positive feedback effect at around day 14 that raise LH to a peak level

25 24 4.1 Hormonal control of the menstrual cycle pituitary gland  ovulation ovary

26 25 4.1 Hormonal control of the menstrual cycle pituitary gland ovary yellow body  LH stimulates development of yellow body and hence progesterone secretion yellow body

27 26 4.1 Hormonal control of the menstrual cycle pituitary gland inhibit  oestrogen and progesterone together inhibit LH and FSH ovary inhibition

28 27 4.1 Hormonal control of the menstrual cycle Let’s look at the menstrual cycle from day 5.

29 28 4.1 Hormonal control of the menstrual cycle Before ovulation 1 The pituitary gland secretes FSH. 2 FSH stimulates the development of follicles. As the follicle matures, it secretes more oestrogen. to chart 3 Under the action of oestrogen, the uterine lining begins to thicken.

30 29 4.1 Hormonal control of the menstrual cycle 4 Oestrogen level continues to rise and reaches a peak just before ovulation. A high level of oestrogen stimulates FSH and LH secretion. The peaks of FSH and LH occur just after the oestrogen peak. 5 A high level of LH causes ovulation to occur on day 14. Before ovulation to chart

31 30 4.1 Hormonal control of the menstrual cycle After ovulation 6 The remaining follicle cells form the yellow body. A high level of LH stimulates the yellow body to secrete oestrogen and progesterone. Oestrogen level rises again and progesterone level reaches a peak. 7 Under the action of oestrogen and progesterone, the uterine lining remains thick. to chart

32 31 4.1 Hormonal control of the menstrual cycle After ovulation 8 High levels of oestrogen and progesterone together inhibit FSH and LH secretion. A low level of LH causes the yellow body to degenerate around day 24. to chart

33 32 4.1 Hormonal control of the menstrual cycle After ovulation 9 The yellow body gradually stops secreting oestrogen and progesterone and the thickened uterine lining soon breaks down. Also, the inhibition of oestrogen and progesterone on FSH secretion is removed. The pituitary gland secretes more FSH again and the cycle repeats. to chart

34 33 4.1 Hormonal control of the menstrual cycle levels of pituitary hormones in blood events in ovary levels of ovarian hormones in blood thickness of uterine lining to text

35 34 Cyclic secretion of GnRH* from the hypothalamus –And of FSH and LH from the anterior pituitary orchestrates the female reproductive cycle Five positive and negative feedback Five hormones involved in an elaborate scheme involving both positive and negative feedback *Gonadotropin-releasing hormone

36 35 Hormone Site of Secretion Target Organ Function Follicle Stimulating Hormone (FSH) Pituitary gland Ovary stimulates the growth & development of the follicle stimulates secretion of oestrogen effect of LH in stimulating ovulation OestrogenOvary Endometrium (lining of the uterus) stimulates repair of uterine lining at high conc. inhibits FSH, however during 'pituitary hormone surge' it stimulates further FSH production as conc. peaks stimulates release of LH Lutenising Hormone (LH) PituitaryOvary stimulates the final development of the follicle stimulates ovulation stimulates the development of the corpus luteum stimulates production of progesterone Progestrone Corpus luteum Uterus maintains uterine lining endometrium) inhibits release of FSH inhibits release of LH fall in conc. results in menstruation fall in conc. removes inhibition of FSH and a new cycle begins.

37 36 Feedback control of human menstrual cycle Atresia of corpus luteum -- degeneration and resorption of corpus luteum in ovary Estradiol -- Oestrogen

38 37 Hormonal feedback control of menstrual cycle

39 38 The reproductive cycle of the human female

40 39 The reproductive cycle of the human female

41 40 4.1 Hormonal control of the menstrual cycle If fertilization occurs … placenta human chorionic gonadotrophin (HCG) acts like LH secretes prevents degeneration of yellow body  secretes oestrogen and progesterone  uterine lining remains thick for embryo development

42 41 4.1 Hormonal control of the menstrual cycle What is the significance of hormonal control of the menstrual cycle?

43 42 4.1 Hormonal control of the menstrual cycle i) Ensure one ovum is released at a time after ovulation, high levels of oestrogen and progesterone together inhibit FSH and LH secretion  prevents maturation of another follicle Higher survival chance!

44 43 4.1 Hormonal control of the menstrual cycle Avoid wasting of energy! i) Ensure one ovum is released at a time after ovulation, high levels of oestrogen and progesterone together inhibit FSH and LH secretion  prevents maturation of another follicle

45 44 4.1 Hormonal control of the menstrual cycle ii) Prepare for implantation oestrogen and progesterone stimulate the thickening of the uterine lining

46 45 4.1 Hormonal control of the menstrual cycle iii) Prepare for the next possible pregnancy if no fertilization occurs, levels of oestrogen and progesterone fall which causes menstruation to occur and the pituitary gland secretes more FSH again the menstrual cycle repeats

47 46 1 Hormonal control of menstrual cycle: 4.1 Hormonal control of the menstrual cycle

48 47 a After ovulation, levels of oestrogen and progesterone together inhibit FSH and LH secretion. 2 Significance of hormonal control of the menstrual cycle: high 4.1 Hormonal control of the menstrual cycle

49 48 a This prevents the maturation of another follicle and ensures only one ovum is released in each cycle. This would result in higher survival chance of the foetus. 2 Significance of hormonal control of the menstrual cycle: 4.1 Hormonal control of the menstrual cycle

50 49 b Oestrogen and progesterone stimulate the thickening of the uterine lining to prepare for the 2 Significance of hormonal control of the menstrual cycle: implantation 4.1 Hormonal control of the menstrual cycle of the embryo.

51 50 c If no fertilization occurs, levels of oestrogen and progesterone fall which causes to occur. The pituitary gland begins to secrete more again. 2 Significance of hormonal control of the menstrual cycle: menstruation 4.1 Hormonal control of the menstrual cycle FSH

52 51 c The menstrual cycle repeats to prepare for the next possible pregnancy. 2 Significance of hormonal control of the menstrual cycle: 4.1 Hormonal control of the menstrual cycle

53 52 4.2 Use of hormones used as contraceptives or in the treatments of infertility

54 53 How are hormones used to prevent pregnancy? contraceptive pills contain synthetic progesterone or a combination of synthetic oestrogen and progesterone  high levels inhibit FSH and LH secretion  follicle development and ovulation do not occur 4.2 Use of hormones

55 54 4.2 Use of hormones for 21 days contraceptive pills for 28 days hormone-free

56 55 4.2 Use of hormones contraceptive patches and injections to be replaced weekly to be taken every 3 months

57 56 How the injection works (ref) The contraceptive injection works in the same way as the implant. It steadily releases the synthetic hormone progestogen into your bloodstream. The continuous release of progestogen: stops a woman releasing an egg every month (ovulation) thickens the mucus from the cervix (neck of the womb), making it difficult for sperm to pass through to the womb and reach an unfertilised egg makes the lining of the womb thinner so that it is unable to support a fertilised egg Disrupted periods Periods irregular and may be very heavy, or shorter and lighter, or stop altogether. This may settle down after the first year, but may continue as long as the injected progestogen remains in your body. It can take a while for your periods and natural fertility to return after you stop using the injection. It takes around eight to 12 weeks for injected progestogen to leave the body, but you may have to wait longer for your periods to return to normal if you are trying to get pregnant.

58 57 morning-after pills contain a high dose of synthetic progesterone or a combination of synthetic oestrogen and progesterone 4.2 Use of hormones  prevent pregnancy after sexual intercourse  prevent ovulation and implantation

59 58 They are not for regular use and must be prescribed by doctors. 4.2 Use of hormones

60 59 How are hormones used to treat infertility? causes of infertility: 4.2 Use of hormones -does not produce enough sperm -sperm have low motility -sperm have structural defects

61 60 How are hormones used to treat infertility? causes of infertility: 4.2 Use of hormones -fails to release ova from the ovaries -oviducts are blocked -uterine environment does not allow implantation

62 61 fertility drugs contain: 4.2 Use of hormones  stimulates follicle development - FSH

63 62 4.2 Use of hormones  stimulates ovulation - LH fertility drugs contain:

64 63 4.2 Use of hormones  stimulates the thickening of the uterine lining to prepare for implantation of the embryo - synthetic oestrogen and progesterone fertility drugs contain:

65 64 are present in 1 Synthetic and oestrogen 4.2 Use of hormones contraceptives. They inhibit and secretion by the pituitary progesterone FSH LH gland. This prevents follicle development and ovulation, so that no ova are released into the oviducts for fertilization.

66 65 2a FSH, LH,, synthetic oestrogen and progesterone are present in fertility drugs. HCG 4.2 Use of hormones

67 66 2b FSH promotes development. LH and HCG stimulate. Synthetic oestrogen and progesterone stimulate the thickening of the uterine lining to prepare for follicle 4.2 Use of hormones ovulation implantation.

68 67 What are the hormones present in the drugs? 1 The drugs contain synthetic oestrogen and progesterone.

69 68 How do the drugs prevent menstruation? 2 High levels of oestrogen and progesterone in blood maintain the thickness of the uterine lining to prevent menstruation.

70 69 How can menstruation be resumed? 3 Menstruation will resume after the female has stopped taking the drugs.

71 70 is controlled by interaction of Menstrual cycle ovarian hormones pituitary hormones can be used as contraceptivestreatment of fertility

72 71 include follicle development pituitary hormones luteinising hormone (LH) follicle stimulating hormone (FSH) stimulates ovulation yellow body formation

73 72 ovarian hormones include progesterone oestrogen low levels cause menstruation uterine lining stimulate thickening of implantation to prepare for


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