Unit P: Reproduction

1. 0 Unit P:Reproduction

2. 0 • Baby Bonanza • The increased use of fertility drugs • Has caused an increase in the number of multiple births in the United States • Fertility drugs are sometimes too effective

3. Standards • I can describe structures and functions of the male and female reproductive systems. • I can outline the pathway of sperm from the male to the fertilization of the egg. • I can compare and contrast male and female gametes. • I can compare and contrast male and female primary and secondary sex characteristics. • I can outline (with examples) both positive and negative feedback loops. • I can outline the events after implantation to childbirth and outline hormonal control. • I can explain and outline the events of the uterine and ovarian cycle, including the hormonal control.

4. 0 HUMAN REPRODUCTION • Reproductive anatomy of humans • Both sexes in humans • Have a set of gonads where gametes are produced • Have ducts for delivery of the gonads and structures for copulation

5. Rectum (digestive system) Urinary bladder (excretory system) Seminal vesicle Vas deferens Ejaculatory duct Pubic bone Erectile tissue of penis Prostate gland Bulbourethral gland Urethra (excretory system) Penis Vas deferens Epididymis Glans of penis Testis Prepuce Scrotum 0 Male Reproductive Structures • Reproductive anatomy of the human male • A man’s testes produce sperm During ejaculation sperm and the nourishing fluid, called semen, are expelled through the penis

6. Urinary bladder (excretory system) Seminal vesicle (behind bladder) Prostate gland Bulbourethral gland Urethra Erectile tissue of penis Scrotum Vas deferens Epididymis Testis Glans of penis 0 • Several glands contribute to the formation of fluid that nourishes and protects sperm

7. Colorized SEM 500 0 • The Properties of Sperm Cells • Only one sperm fertilizes an egg

8. Middlepiece Plasma membrane Neck Head Tail Mitochondrion(spiral shape) Nucleus Acrosome 0 • During fertilization a sperm releases enzymes from the acrosome that pierce the egg’s coat … more details on fertilization later!

9. Stimuli from other areas in the brain Hypothalamus Releasing hormone Anterior pituitary Negative feedback LH FSH Androgenproduction Testis Sperm production 0 • A negative feedback system of hormones controls sperm production

10. Epididymis Penis Testis Scrotum 2n Diploid cell Testis Seminiferous tubule Differentiation andonset of Meiosis I Cross section ofseminiferoustubule 2n Primary spermatocyte (in prophase of Meiosis I) Meiosis I completed Secondary spermatocyte n n (haploid; double chromatids) Meiosis II Developing sperm cells(haploid; single chromatids) n n n n Differentiation Sperm cells n n n n Center ofseminiferous tubule (haploid) 0 • The formation of sperm and ova requires meiosis • Spermatogenesis, the formation of sperm cells takes about 65–75 days in the human male • Primary spermatocytes, which are diploid, are made continuously in the testes and undergo meiosis to produce haploid sperm

11. In embryo Diploid cell 2n Differentiation andonset of Meiosis I Primary oocyte 2n Present at birth (arrested in prophaseof Meiosis I) Completion of Meiosis Iand onset of Meiosis II Secondary oocyte n Firstpolar body (arrested at meta-phase of Meiosis II;released from ovary) n Entry of sperm triggerscompletion of Meiosis II Ovum Secondpolar body n n (haploid) 0 • Each month one primary oocyte matures to form a secondary oocyte, which can be fertilized • Primary oocyte completes meiosis and becomes a haploid ovum

12. Female reproductive system • Ovaries • produces eggs & hormones • Uterus • nurtures fetus; lining builds up each month • Fallopian tubes • tubes for eggs to travel from ovaries to uterus • Cervix • opening to uterus, dilates 10cm (4 inches) for birthing baby • Vagina • birth canal for birthing baby

13. Ovaries Oviduct Follicles Corpus luteum Wall of uterus Uterus Endometrium (lining of uterus) Cervix (“neck” of uterus) Vagina 0 Female Reproductive Structures • A woman’s ovaries contain follicles that nurture eggs and produce sex hormones

14. Egg cell Ovary LM 200 0 • Oviducts convey eggs to the uterus where the eggs develop

15. Oviduct Ovary Uterus Rectum (digestive system) Urinary bladder (excretory system) Pubic bone Cervix Urethra(excretory system) Vagina Shaft Glans Clitoris Bartholin’s gland Prepuce Labia minora Anus (digestive system) Labia majora Vaginal opening 0 • The uterus opens into the vagina which receives the penis during intercourse and forms the birth canal • Other structures of the female reproductive system include • Labia, the clitoris, Bartholin’s glands, and the cervix

16. 0 • Hormones synchronize cyclic changes in the ovary and uterus • The ovarian cycle includes changes in the ovary that occur about every 28 days • The menstrual cycle involves changes that occur in the uterus • An Overview of the Ovarian and Menstrual Cycles • Events in the menstrual cycle are synchronized with the ovarian cycle, which occurs about every 28 days • Uterine bleeding, called menstruation • Includes the breakdown of the endometrial lining • Usually persists for 3–5 days • After menstruation • The endometrium, the lining of the uterus, regrows

17. 0 • Five hormones synchronize the events in the ovarian cycle

18. LH Menstrual cycle FSH Hypothalamus egg development ovulation = egg release GnRH corpus luteum Pituitary FSH & LH estrogen progesterone Ovaries lining of uterus estrogen Body cells days 0 7 14 21 28

19. The Ovarian Cycle • Follicular Phase – Day 1-13 -Starts with anterior pituitary gland releases FSH (follicle stimulating hormone) -FSH targets the ovaries and causes ONE follicle to ripen

20. AS the follicle begins to mature it releases ESTROGEN • Estrogen causes the uterine lining to rebuild

21. When estrogen levels get high enough they cause a surge in the release of LH or luteinizing hormone • Surge in LH causes the release of egg or OVULATION (Day 14)

22. Ovulation – Day 14 • This is when the egg is released from the ovary • The follicle ruptures and the egg exits out, causing a crater on the side of the ovary.

23. Corpus Luteum • Luteal Phase Day 15-28 • The structure that is left in the ovary is a gland like structure that releases the second female PROGESTERONE • Progesterone causes the uterine lining to thicken even more and become secretory.

24. No fertilization….. • If no fertilization of the egg occurs then the egg will deteriorate. • As well as the corpus luteum also degenerates • This causes - Progesterone & Estrogen levels to drop significantly.

25. Ovarian Cycle

26. Menstrual Cycle • Flow Phase Day 1-5 • Low levels of both female hormones will cause the uterine lining to be shed (The Flow Phase) • AS well the low levels of hormones will cause the anterior pituitary to release FSH and LH.

27. Proliferative Phase Day 6-14 • Estrogen levels increase (from the follicle) and cause the endometrium to rebuild

28. Secretory Phase Day 15 – 28 • Progesterone levels cause the endometrium to double in thickness and become secretory

29. A Control by hypothalamus Inhibited by combination of estrogen and progesterone Stimulated by high levels of estrogen Hypothalamus Releasing hormone Anterior pituitary FSH LH 1 B Pituitary hormones in blood 4 LH peak triggers ovulation and corpus luteum formation • The ovarian and menstrual cycles 6 LH FSH FSH LH 2 Ovarian cycle C 5 Corpus luteum Degenerating corpus luteum Growing follicle Mature follicle Ovulation Pre-ovulatory phase Post-ovulatory phase Progesterone and estrogen Estrogen D Ovarian hormones in blood 3 7 8 Estrogen Progesterone Progesterone and estrogen Estrogen Menstrual cycle E Endometrium 0 5 10 14 15 20 25 28 Days Menstruation

30. 0 • If fertilization of an egg occurs • Outer layers of cells of the embryo secrete a hormone – HCG (human chorionic gonadotropin) this causes the corpus luteum (in the ovary) to be maintained. • Corpus luteum continues to produce progesterone (and estrogen) this shuts off the anterior pituitary so no ovulation will occur and also maintains lining of uterus.

31. 0 CONNECTION • Sexual activity can transmit disease • Sexual intercourse carries the risk of exposure to sexually transmitted infections (STIs)

32. 0 • STIs common in the United States

33. Skin patch Condom Diaphragm Spermicide Birth control pills 0 CONNECTION • Contraception can prevent unwanted pregnancy • Contraception is the deliberate prevention of pregnancy

34. 1 The spermapproachesthe egg The sperm’sacrosomal enzymesdigest the egg’s jellycoat 2 3 Proteins on thesperm head bind toegg receptors The plasmamembranes of spermand egg fuse 4 The sperm nucleusenters the eggcytoplasm 5 A fertilizationenvelope forms 6 The nuclei of sperm and egg fuse 7 0 Sperm • If contraception doesn’t work…..The Process of Fertilization occurs • Sperm surface proteins bind to egg receptor proteins • Sperm and egg plasma membranes fuse, and the two nuclei unite • Changes in the egg membrane prevent entry of additional sperm • The fertilized egg (zygote) develops into an embryo Nucleus Spermhead Acrosome Plasmamembrane Acrosomalenzymes Receptor proteinmolecules Plasmamembrane Spermnucleus Vitellinelayer Cytoplasm Eggnucleus Jellycoat Egg cell Zygote nucleus

35. 0 EMBRYONIC DEVELOPMENT • Fertilization results in a zygote and triggers embryonic development • Embryonic development begins with fertilization: the union of sperm and egg to form a diploid zygote – occurs in oviduct

36. 0 HUMAN DEVELOPMENT • The embryo and placenta take shape during the first month of pregnancy • Pregnancy, or gestation is the carrying of developing young within the female reproductive tract

37. 0 • The Placenta • After 3 months placenta is fully formed and takes over hormone production (estrogen, progesterone) – now the corpus luteum degenerates • The placenta absorbs food and oxygen from the mother’s blood to nourish the embryo (remember fetal circulation??)

38. 0 • Human development from conception to birth is divided into three trimesters • Each trimester is about three months in length • The First Trimester • The most rapid changes occur during the first trimester

39. 0 • By 9 weeks the embryo is called a fetus

40. 0 • The Second Trimester • The second trimester involves an increase in size and general refinement of the human features

41. 0 • At 20 weeks the fetus is about 19 centimeters long, and weighs half a kilogram

42. 0 • The Third Trimester • The third trimester is a time of rapid growth, which ends in birth

44. Estrogen Oxytocin fromovaries from fetusand pituitary Induces oxytocinreceptors on uterus Stimulates uterusto contract Positive feedback Stimulatesplacenta to make Prostaglandins Stimulate morecontractionsof uterus 0 • Childbirth is hormonally induced and occurs in three stages • The birth of a child is brought about by a series of strong, rhythmic contractions of the uterus, called labor • Estrogen makes the uterus more sensitive to oxytocin which acts with prostaglandins to initiate labor

45. Dilation of the cervix 1 2 Expulsion: delivery of the infant • Labor occurs in three stages • Dilation, • Expulsion • Delivery of the placenta

46. 0 CONNECTION • Reproductive technology increases our reproductive options • New techniques can provide help to infertile couples • Some of these methods raise important ethical and legal questions