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Reproductive system

Reproductive system. Reproductive system. Gametic meiosis All Animal Kingdom Gametes made by diploid organism directly by meiosis Syngamy makes zygote, which develops into adult. Fertilization. External: Eggs and sperm released outside of bodies of male/female

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Reproductive system

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  1. Reproductive system

  2. Reproductive system • Gametic meiosis • All Animal Kingdom • Gametes made by diploid organism directly by meiosis • Syngamy makes zygote, which develops into adult

  3. Fertilization • External: Eggs and sperm released outside of bodies of male/female • Most marine bony fish, most amphibians.

  4. Fertilization • Internal: Sperm deposited inside body of female • Reptiles, birds, mammals

  5. Vertebrate Reproduction(Internal fertilization) • Oviparity: Eggs fertilized internally. Deposited outside mother’s body to develop. • Some cartilagenous fish, some bony fish, some amphibians, most reptiles, all birds, few mammals (monotremes).

  6. Vertebrate Reproduction Ovoviviparity: Eggs fertilized internally, remain in mother. But rely on yolk for nourishment. Young developed and hatched when released. • Some bony fish, some cartilagenous fish, some amphibians, many reptiles Salamandra female giving birth to larvae

  7. Vertebrate Reproduction • Viviparity: Young develop in mother and obtain nourishment mainly from mother (rather than ____________). • Most cartilagenous fishes, few bony fishes, some amphibians, few reptiles, almost all mammals.

  8. Reproductive system • Here, we emphasize human system (rat seen in lab) • Start with male, move to female

  9. Reproductive system • Male: • 1) Makes gametes (sperm) by meiosis • 2) Delivers sperm to vagina in female system

  10. Reproductive system • Sperm cell: • Flagellum to swim with • Mitochondria for energy • Nucleus (haploid) in head • Acrosome: special ____________, contains enzymes that help penetrate layers around egg.

  11. Reproductive system • Male reproductive system • 1) Testes (plural: males have 2). Make sperm and androgens (male hormones, such as testosterone) • In bag called scrotum.

  12. Reproductive system • 1) Testes: Seminiferous tubules • 1) germinal cells divide (mitosis) to produce primary spermatocyte • 2) primary spermatocyte divides by meiosis to make 4 spermatids • 3) Spermatids develop into sperm • 4) Process aided by ______________ cells, which help spermatids transform into sperm.

  13. Reproductive system • Making sperm: a fulltime job • 100-200 million formed per day, takes 100 days to make them • Influenced by temperature • Normal testis temperature is 34 degrees, compared to 37 degrees internal body temperature.

  14. Reproductive system • Male reproductive system • 2) Ducts to carry sperm. Epididymis: collecting duct at testis. Vas deferens: duct from epididymis to seminal vesicle. Ejaculatory ducts: from seminal vesicle to prostate gland.

  15. Reproductive system • Male reproductive system • 3) Accessory glands (package sperm). Seminal vesicles: store sperm. Bulbourethral gland and prostate gland (produce ____________).

  16. Reproductive system • Male reproductive system • 3) Accessory glands (package sperm). • Semen: fluid that enhances longevity of sperm

  17. Reproductive system • Semen: fluid that enhances longevity of sperm • Contains: • water • sugars (fructose and glucose): used by sperm for energy • __________________: neutralizes acidity from urine in male urethra and acidic conditions in vagina • prostaglandins: hormones that stimulate contractions of smooth muscle in female system • vitamins, minerals, amino acids, etc.

  18. Reproductive system • Male reproductive system • 4) Penis: copulatory organ, delivers sperm to __________ of female • When male excited, blood flow out decreased. Blood fills 2 corpora cavernosa (spongy tissue bodies on each side of penis) during erection.

  19. Reproductive system • Female reproductive system • 1) Produces gametes (eggs) • actually oocytes: cells ______________ to being eggs! • 2) Also nourishes embryo during gestation period (time from fertilization to birth: 9 months for human).

  20. Reproductive system • Female reproductive system • 1) Ovary (2 of them): Where oocytes formed • 2) Fallopian tube (2 of them): connect ovary to uterus • 3) Uterus: where fertilized egg implants and embryo develops

  21. Reproductive system • Female reproductive system • 4) Cervix: entrance to uterus • 5) Vagina: connects uterus to outside body

  22. Reproductive system • Making oocytes in ovary • Process starts before birth, when germinal cells produce primary oocytes. These start meiosis I but stop at prophase I at time of birth as primary follicles.

  23. Reproductive system • Follicles contain oocyte and cluster of other special cells • Each female has about 2 ____________ follicles at birth.

  24. Reproductive system • Once puberty begins, one primary follicle matures each month during menstrual cycle. • Maturation, called ______________, ruptures follicle and releases secondary oocyte.

  25. Reproductive system • In secondary oocyte, meiosis I completed and meiosis II started. Stops at metaphase II. • Will complete meiosis II to make egg only if fertilized by sperm!

  26. Reproductive system • Note that follicle cells stay alive and secrete hormones for a time after secondary oocyte released • Become corpus luteum.

  27. Reproductive system • Hormones made by corpus luteum increase thickening of lining of uterus • This readies uterus in case fertilization occurs • Oocyte moves down Fallopian tube by _________ lining tube.

  28. Reproductive system • Menstrual cycle (takes about 28 days)

  29. Reproductive system • 1) pituitary gland (in head under brain) secretes follicle stimulating hormone (FSH) • 2) Follicles in ovaries begin to develop (only one continues to end)

  30. Reproductive system • 3) Follicles release _____________: uterus lining starts to thicken

  31. Reproductive system • 4) Estradiol stimulates more FSH. Also luteinizing hormone (LH) made by pituitary. • 5) Peak of FSH and LH at day 14 causes ovulation: release of secondary oocyte from 1 follicle.

  32. Reproductive system • 6) Remnants of follicle are corpus luteum • 7) Secretes estradiol and progesterone. They influence pituitary to decrease FSH and LH production. Follicles stop developing.

  33. Reproductive system • 8) After several days, corpus luteum starts to degenerate • 9) Estradiol and progesterone levels drop

  34. Reproductive system • 10) Uterine lining(endometrium) sloughs off (period starts) • 11) Decrease in estradiol and progesterone cause pituitary to increase _______ production • 12) Cycle starts again.

  35. Reproductive system • If fertilization happens: • Embryo implants in uterine wall • Eventually, placenta takes over production of estradiol and progesterone. Lining stays thickened (no period). No more follicles develop.

  36. Reproductive system • Lost along the way: fertilized oocyte can get outside system and create ___________ pregnancy (implants in wrong places) • Problem: won’t develop normally. Must be removed or can kill mother.

  37. Manipulating the system • Birth control (or how not to make a baby) • See also: www.plannedparenthood.org

  38. Manipulating the system • 1) Abstinence. • Variation: rhythm method. Time between _________ release and arrival in uterus about 5 days (after ovulation). Sperm can remain alive in woman for several days.

  39. Manipulating the system • 2) Sperm blockage (condom, cervical cap or diaphagm)

  40. Manipulating the system • 3) Sperm destruction • washing sperm out (douche) • spermicide foams/jellies

  41. Manipulating the system • 4) Preventing ovulation: the pill and implants of various types. Contain chemicals that act like ______________ (prevent follicle development).

  42. Manipulating the system • 5) Preventing embryo implantation: IUD (intrauterine device). Irritates uterine lining.

  43. Manipulating the system • 6) Sterilization • vasectomy for man (cutting/tying vas deferens) • cutting/tying Fallopian tubes for woman.

  44. Manipulating the system • Fertility clinics (how to make a baby) • _______% of couples have difficulty conceiving a child • About half cases due to male infertility, other half female infertility

  45. Manipulating the system • Male infertility: • Large numbers sperm needed due to barriers in journey • 1) long distance (sperm swim 3 mm/hour) • 2) acidic conditions in vagina • 3) most are active for <48 hours • Typically many hundreds of millions deposited, only few hundred reach fallopian tubes • So, numbers matter (Normal is____ million sperm/ml. Low is <20 million/ml). • Also vigor (activity level) and appearance (morphology) of sperm matter.

  46. Manipulating the system • Fertility clinics (how to make a baby) • Female infertility: • ______________ problems • Anatomical problems

  47. Manipulating the system • For both men and women: age ___________ fertility

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