Chapter 48

1. Chapter 48 Reproduction

2. Asexual reproduction • A single parent endows its offspring with genes identical to its own • Energy efficient • Most successful in a stable environment

3. Means of asexual reproduction • Budding • Part of the parent’s body grows and separates from the rest of the body • Fragmentation • The parent’s body breaks into pieces • Each piece can grow into a new animal • Parthenogenesis • An unfertilized egg develops into an adult

4. Asexual reproductionby budding

5. Sexual reproduction • Offspring produced by fusion of two gametes • Ovum • Sperm • A fertilized egg (zygote) forms • Promotes genetic variety and is adaptive in an unstable environment

6. External fertilization • Mating partners typically release eggs into the water simultaneously • Internal fertilization • Male delivers sperm into the female’s body • Hermaphroditism • Single individual produces eggs and sperm

7. Human male reproductive system • Testes • Housed in the scrotum • Contain the seminiferous tubules, where sperm production takes place • Interstitial cells secrete testosterone • Sertoli cells produce signaling molecules and a fluid that nourishes sperm cells

8. Human male reproductive system, cont. • Sperm • Stored in the epididymis and vas deferens • During ejaculation, sperm pass from the vas deferens to the ejaculatory duct and into the urethra

9. Human male reproductive system, cont. • Penis • Three columns of erectile tissue • Two cavernous bodies • One spongy body that surrounds the urethra • Erectile tissue becomes engorged with blood and causes erection

10. Male reproductivesystem

11. Spermatogenesis • Takes place in the seminiferous tubules • Spermatogonia divide by mitosis • Head of a sperm consists of the nucleus and an acrosome, containing enzymes that help penetrate the egg

12. Spermatogenesis in the seminiferous tubules

13. Spermatogenesis

14. Sperm pass in sequence through • Seminiferous tubes of the testes • Epididymis • Vas deferens • Ejaculatory duct • Urethra

15. Structure of amature sperm

16. Endocrine regulation of reproduction in the human male • Testosterone establishes and maintains • Primary sex characteristics • Secondary sex characteristics

17. Internal structure of the penis

18. Endocrine regulation of reproduction involves the • Hypothalamus • GnRH • Pituitary gland • FSH and LH • Testes • Testosterone • ABP and inhibin

19. Principal male reproductive hormones

20. Regulation of reproduction in the male

21. Human female reproductive system • Ovaries • Produce gametes • Steroid hormones estrogen and progesterone • Fertilization takes place in the oviducts

22. Female reproductive system

23. Human female reproductive system, cont. • Uterus • Incubator for the embryo • Endometrium thickens each month • Cervix extends into the vagina

24. Human female reproductive system, cont. • Vagina • Lower part of the birth canal • Vulva includes the labia majora, labia minora, vestibule, clitoris, and mons pubis

25. Female reproductive system,anterior view

26. Human female reproductive system, cont. • Breasts • Function in lactation • Prolactin stimulates milk production • Oxytocin stimulates milk ejection from the alveoli into the ducts

27. Development of a human ovum • Oogenesis takes places in the ovaries • Oogonia differentiate into primary oocytes • Primary oocyte and granulosa cells make up a follicle

28. Oogenesis

29. Development of a human ovum, cont. • As the follicle grows • Connective tissue cells form a layer of theca cells • Primary oocyte undergoes meitosis, giving rise to a secondary oocyte and a polar body

30. Development of follicles in the ovary

31. Development of a human ovum, cont. • During ovulation • The secondary oocyte is ejected and enters an oviduct to be fertilized • The part of the remaining follicle develops into a corpus luteum

32. Endocrine regulation of reproduction • Preovulatory phase • GnRH stimulates the pituitary to secrete FSH and LH • Estrogen stimulates endometrium development • LH stimulates final maturation of the follicle and ovulation

33. Endocrine regulation of reproduction, cont. • Postovulatory phase • LH promotes development of the corpus luteum • The corpus luteum secretes progesterone and estrogen • If fertilization does not occur, the corpus luteum degenerates, hormone levels fall, and menstruation occurs

34. Principal female reproductive hormones

35. Feedback mechanisms in endocrine regulation of female reproduction

36. Physiological changes that occur during sexual response • Sexual excitement • Plateau • Orgasm • Resolution

37. Human fertilization • Fusion of secondary oocyte and sperm to form a zygote • Embryo implants in the uterus • hCG is the hormone that maintains the corpus luteum • Estrogen and progesterone • Secreted by corpus luteum (first trimester) and then by placenta

38. Fertilization

39. Events following fertilization

40. Human birth process • Several hormones, including estrogen, oxytocin, and prostaglandins regulate parturition • Labor • Divided into three stages • The baby is delivered during the second stage

41. Contraception • Hormonal methods, such as oral contraceptives • Intrauterine devices • Condoms and contraceptive diaphragms • Sterilization (vasectomy or tubal ligation)

42. Sterilization

43. Abortions • Spontaneous miscarriages occur without intervention • Induced abortions • Therapeutic performed to maintain the mother’s health, as birth control, or when the embryo is thought to be grossly abnormal

44. Common sexually transmitted diseases (STDs) • Chlamydia • Gonorrhea • Syphilis • Pelvic inflammatory disease (PID) • Genital herpes • HIV

45. Endocrine regulation of reproduction involves the • Hypothalamus • GnRH • Pituitary gland • FSH and LH • Testes • Testosterone • ABP and inhibin

46. Some types of endocrine signaling

47. Majorchemical groups of hormones