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Reproduction

Reproduction. Topic 6 Standard Level. STARTER : How much do you remember from IGCSE?. Learning Ojectives. Draw and label diagrams of the adult male and female reproductive systems.

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Reproduction

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  1. Reproduction Topic 6 Standard Level

  2. STARTER: Howmuch do yourememberfrom IGCSE?

  3. LearningOjectives • Drawand labeldiagrams of the adult male and female reproductive systems. • Outlinethe role of hormones in the menstrual cycle, including FSH (follicle stimulating hormone), LH (luteinizing hormone), estrogen and progesterone. • Annotatea graph showing hormone levels in the menstrual cycle, illustrating the relationship between changes in hormone levels and ovulation, menstruation and thickening of the endometrium. • Listthree roles of testosterone in males

  4. Hormones • Four main hormones involved in controlling menstruation

  5. The Menstrual Cycle • During the first week of the cycle the pituitary gland is stimulated • It releases follicle stimulating hormone (FSH) AnnotateyourMenstrual cyclehandout as wemovethroughthenextfewslides

  6. FSH stimulates a potential egg cell in the ovary • The cells around the ovum also develop. This is called a follicle. • Follicle cells secrete oestrogen. • Oestrogen stimulates rebuilding of uterus wall. An oocyte (pre-ovum) surrounded by follicle cells

  7. False colour SEM of human uterus wall, approximately 13 days into cycle. Green cells are secretory, and orange cells are ciliated

  8. Initial concentrations of oestrogen are low. • The low concentration has a negative feedback effect on the secretion of FSH.

  9. Negative feedback lowers FSH concentration • As follicle grows is produces larger concentrations of oestrogen. • At a certain threshold, its effect reverses. • It now has a positive feedback effect on secretion of FSH from pituitary. • Also stimulates pituitary gland to release luteinising hormone (LH)

  10. Positive feedback from increasing oestrogen concentration causes increase in FSH and LH from pituitary gland. Follicle gets bigger – releases more oestrogen

  11. Peak of LH causes follicle to burst and release ovum • This is ovulation (on day 14 of the cycle) • Follicle reforms to become structure called corpus luteum (‘yellow body’) • LH stimulates corpus luteum to produce progesterone.

  12. Peak of LH causes ovulation (day 14) Oestrogen falls because follicle is gone, but corpus luteum still produces some. Ovulation – ovum released from follicle. Follicle become corpus luteum

  13. Progesterone completes uterus wall. • Increases blood supply and promotes glycogen storage. • Rising concentrations of progesterone and oestrogen have negative feedback effect on FSH and LH. • This prevents new follicles forming.

  14. Fall in FSH and LH due to negative feedback with oestrogen and progesterone Progesterone produced by corpus luteum. Inhibits FSH and LH Corpus luteum – produces progesterone. Uterus wall fully completed.

  15. Fertilisation must occur within 2 days of ovulation. • Embryo takes 3 days to reach the uterus and implant. • If no embryo implants within a week the corpus luteum starts to break down. • Progesterone and oestrogen concentrations fall. Uterus wall begins to break down. • FSH no longer inhibited, so begins to rise. • Cycle begins again

  16. FSH and LH totally inhibited Breakdown of corpus luteum causes fall in progesterone and oestrogen Corpus luteum begins to break down if no embryo has implanted a week after ovulation

  17. FSH begins to rise since it’s not inhibited by oestrogen and progesterone Low levels of progesterone and oestrogen because there is no follicle or corpus luteum Uterus wall breaks down due to low levels of oestrogen and progesterone New egg cell stimulated by rising FSH levels

  18. Menstrual cycle summaryStick the statement into the correct column!

  19. STARTER: GROUP ACTIVITY:Calculatea) the magnification of the spermb) The maximum diameter of the main body of the ovum

  20. GROUP ACTIVITY:Calculatea) the magnification of the spermb) the maximum diameter of the main body of the ovum a) magnification b) diameter of ovum measured length magnification 70mm X 911 = 0.0768 mm = 76.83µm measured length scale bar label 41mm = 41000 µm 45µm 45µm = X 911

  21. LearningOjectives • Outlinethe process of in vitro fertilization (IVF). • Discussthe ethical issues associated with IVF.

  22. CLASS ACTIVITY: Can younarrateeachphase of the menstrual cyclewithreferencetospecific hormones?

  23. STARTER: Complete thisflow chart in yourworkbooks!

  24. TIMED INDIVIDUAL ACTIVITY:

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