Human Reproduction & Development

1. Human Reproduction & Development Textbook Chapter 36 Review Book Topic 4

2. Reproduction • Necessary process to ensure the continuation of a species • Involves the union of an egg cell and a sperm cell, development of a fetus, and the birth of an infant • Involves organs, glands and hormones of both male and female reproductive systems

3. Sex Cell Development • Males • Occurs in testes • Spermatocytes mature into sperm cells • Occurs daily from puberty to death

4. Females • Occurs in the ovary • Born with all of the immature eggs a female will use monthly from puberty to menopause • All eggs are stored in 1st meiotic division in the ovary until it receives hormone signals to develop

5. Male Reproductive System • Reproductive organ ~ Testes • Located outside of the body cavity in a pouch called the scrotum • Sperm develop- ment requires a temperature lower than 37ºC

6. Reproductive cells ~ Sperm • Produced in testes at the seminiferous tubules • 100-200 million are produced each day • Travel to epididymis • On top of each testes • Sperm mature and are stored there

8. When released from the body, sperm travel through the vans deferens into urethra • Urethra - tube which carries semen and urine out of the body through the penis

9. Sperm require a nourishing fluid to survive long enough to fertilize the egg • Semen – fluid containing sperm, nourishment, and other fluids from male reproductive glands

10. Seminal vesicles (ejaculatory ducts) secrete fluids plus sugar into the semen (provides energy, proteins, and enzymes for sperm) • Prostate gland and bulbourethral glands secretes an alkaline solution to the semen to neutralize acidic conditions the sperm could encounter (ex. urethra, female system, etc.)

12. TRY LABELING THIS!!

13. Answers 1.  TESTIS 2.  EPIDIDYMIS 3.  VAS DEFERENS 4.  URETHRA 5.  BULBOURETHRAL GLAND 6.  SEMINAL VESICLE / EJACULATORY DUCT7.  BLADDER 8.  PROSTATE 9.  PENIS 10. URETHRA

14. Male Hormones • Testosterone ~ hormone necessary for the production of sperm • Made in the testes • Influences male secondary sex characteristics • Facial & body hair • Broad shoulders • Increased muscle development • Deeper voice • Receding hairline & baldness (older)

15. Puberty ~ period of growth when sexual maturity is reached • Three hormones are released from the hypothalamus that influence puberty • Gonadotropin-releasing hormone (GnRH) • Follicle-stimulating hormone (FSH) • Promotes sperm production • Luteinizing hormone (LH) • Promotes production and secretion of testosterone

16. Female Reproductive System • Specialized to produce eggs cells, receive sperm and to provide the perfect environment for fertilization and development of a fetus • Reproductive organ ~ ovaries • Two • About the size of an almond

17. Reproductive cell ~ egg (ovum) • Oocytes ~ immature eggs • Every 28 days, oocyte development is stimulated and becomes an egg • Surrounded by follicle cells • Protection • Nourishment

18. Ovulation ~ mature egg ruptures out of ovary wall

20. After egg is released from ovary • Absorbed by fimbriae (finger-like hair structure) • Travels to oviduct (fallopian tube) which connects to the uterus • Uterus (womb) is where the baby develops before birth • Roughly the size of your fist • Cervix is the narrow opening into the vagina from the uterus

23. Female Hormones • Reproductive hormones ~ estrogen & progesterone • Released by ovaries • Anterior pituitary gland releases LH & FSH

24. During puberty, increases in estrogen cause breasts to develop, hips to widen, and fat tissue to increase • Also will experience first menstrual cycle • Occurs each month to help prepare the female body for pregnancy

25. Reproductive System BrainPop

26. Menstrual Cycle • Length varies from 23 to 35 days • Typically last 28 days • Three phases • Flow phase • Follicular phase • Luteal phase

27. Flow phase • Day 1 ~ menstrual flow begins • Shedding of blood, tissue fluid, mucus and epithelial cells from endometrium (uterine tissue lining) • Bleeding occurs because outer layers of endometrium tear away, rupturing blood vessels • Day 5 ~ repair of endometrial lining • Becomes thicker as cycle continues

28. Follicular phase • Estrogen level is low • Anterior pituitary releases FSH & LH to stimulate the egg to mature in the ovary • 1 week • Egg maturation releases estrogen causing FSH & LH levels to drop (negative feedback)

29. Day 12 ~ high levels • of estrogen cause • the release of a • surge of LH • Causes follicle to rupture, releasing egg • Ovulation occurs

31. Luteal phase • After ovulation, follicle changes into the corpus luteum • Produces high amounts of progesterone • Breaks down at end of cycle, production of estrogen and progesterone stops • Signals release of endometrium lining • New flow phase begins

33. If egg is fertilized, development will occur and menstrual cycle does not begin • Progesterone levels will remain high • Increased flow of blood to endometrium • Corpus luteum does not break down • Endometrium accumulates lipids and secretes fluid rich in nutrients for developing embryo

35. Menstrual Cycle BrainPop

36. Fertilization • Fertilization ~ process where sperm and egg combine, forming a diploid cell • Occurs in upper portion of the oviduct near the ovary • Sperm is deposited in the vagina through ejaculation (release of semen from the penis) • Sperm can survive for 48 hours inside the female • Unfertilized egg can only survive for 24 hours

37. Out of the 300 million sperm deposited, only a couple hundred will reach the egg • A single sperm cannot penetrate the plasma membrane of the egg • One sperm will fertilize the egg but many are needed for the process to occur

38. Tip of each sperm contains lysosomes which contain enzymes used to digest the eggs membrane • When weak enough, one sperm penetrates, fertilizing the egg • Immediately the egg forms a barrier to prevent any other sperm from penetrating the fertilized egg

40. Embryo Development • Fertilized egg is known as a zygote • Travels through oviduct by smooth muscle contractions and by cilia lining the oviduct • 30 hrs after fertilization, zygote undergoes first mitosis and cell division • After 3 days, zygote leaves oviduct and enters uterus • Now referred to as a morula (solid ball of cells)

42. Day 5, morula has developed into a blastocyst (hallow ball of cells) • Attaches to uterine lining on day 6 and is fully implanted by day 10 • Blastocyst stage is where identical twins can result if cells are split into two

43. Embryonic Development Structures • Amnion – thin sac which forms around the embryo and is filled with amniotic fluid to cushion and insulate the egg. • Chorion, the allantois, and yolk form the placenta two weeks after fertilization • Chorion and allantois help form the placenta • Yolk serves as the first red blood cell formation for the embryo

45. Placenta – organ that provides food and oxygen as well as removes wastes from the baby (grows into the wall of the uterus) • Umbilical chord contains blood vessels which serves as the connection between mother and child (no blood ever mixes, just very close so diffusion occurs)

48. 6 Weeks

49. 12 Weeks

50. 14 Weeks