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Human Reproduction

Human Reproduction. Difference between Meiosis and Mitosis. Meiosis I. Interphase. Prophase I. Metaphase I. Anaphase I. Telephase I. Meiosis II. Prophase II. Metaphase II. Anaphase II. Telephase II. Male Uncomplicated Produce sperm 2-4 MILLION every day. Female Very Complicated!

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Human Reproduction

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  1. Human Reproduction

  2. Difference between Meiosis and Mitosis

  3. Meiosis I Interphase Prophase I Metaphase I Anaphase I Telephase I

  4. Meiosis II Prophase II Metaphase II Anaphase II Telephase II

  5. Male Uncomplicated Produce sperm 2-4 MILLION every day Female Very Complicated! One egg Once a month Careful coordination of hormones & body Timing perfect! Anatomy – similaritiesFunction – VERY different!

  6. Male Reproductive System

  7. Human reproduction involves intricate anatomy and complex behavior • Reproductive Anatomy of the Human Male. • External: - penis - scrotum • Internal: - gonads - accessory sex glands and ducts.

  8. Male Reproductive System

  9. Testes

  10. Male Reproductive System

  11. Male Reproductive System

  12. External structure of the penis: • glans penis • prepuce (foreskin) • There is no verifiable health benefit to circumcision.

  13. The penis is composed of three layers of spongy erectile tissue. • During sexual arousal the erectile tissue fills with blood from arteries. • The resultant increased pressure seals off the veins that drain the penis. • The engorgement of the penis with blood causes an erection.

  14. Testes are the male gonads. • seminiferous tubules- form sperm • Leydig cells (interstitial cells)- produce androgens (ex. Testosterone, ABP).

  15. Testes are located in the scrotum, outside the body cavity. • This keeps testicular temperature cooler than the body cavity. • The testes develop in the body cavity and descend into the scrotum just before birth.

  16. Sperm Pathway Membranous urethra Prostatic urethra

  17. Semen • Seminal fluid is thick, yellowish, and alkaline. • It contains mucus, fructose, a coagulating enzyme, ascorbic acid, and prostaglandins. • Accessory glands: • seminal vesicle • prostate gland • bulbourethral gland

  18. Seminal vesicle: • A pair of glands that secrete a liquid component of semen into the vas deferens. • Secretion is alkaline • Contains fructose, asorbic acid, coagulating enzyme, prostaglandin Seminal vesicle

  19. Prostate gland: • Location- surrounds and opens into the urethra where it leaves the bladder. • Secretion- slightly alkaline fluid that activates the sperm and prevents them from sticking together • Prostate problems are common in males over 40. • Prostate cancer is one of the most common cancers in men. Prostrate gland Prostate

  20. Bulbourethral gland (Cowper’s gland): • Location- paired glands that lie beneath the prostate • Secretion- a thick, clear alkaline mucous that drains into the membranous urethra. • Function- It acts to wash residual urine out of the urethra when ejaculating semen-- raises pH; neutralizes acidity of urine. Bulbourethral gland

  21. Ejaculation • Ejaculation propels sperm from the epididymis to the vas deferens. • The vas deferens run from the scrotum and behind the urinary bladder. • Here each vas deferens joins with a duct from the seminal vesicle to form an ejaculatory duct. • The ejaculatory ducts open into the urethra. • The urethra drains both the excretory and reproductive systems.

  22. Ejaculate • A male usually ejaculates about 2 – 5 mL of semen; each milliliter containing about 50 – 130 million sperm. • Bulbourethral fluid also carries some sperm released before ejaculation. • This is one of the reasons why the withdrawal method of birth control has a high failure rate.

  23. Spermatogenesis

  24. SPERMIOGENESIS

  25. Mature Spermatozoa acrosome head nucleus tail mitochondria

  26. Seminiferous Tubules

  27. Seminiferous Tubules spermatozoa Sertoli cell spermatids 2º spermatocyte 1º spermatocyte spermatogonium

  28. Sperm Maturation & Development

  29. Hormones Involved in Spermatogenesis • Gonadotropin Releasing Hormone (GnRH) • Follicle Stimulating Hormone (FSH) • Interstitial Cell Stimulating Hormone (ICSH=LH) • Testosterone • Inhibin • ABP

  30. Hormonal Control of Spermatogenesis Hypothalamus GnRH Anterior Pituitary ICSH FSH

  31. Hormonal Control of Spermatogenesis ICSH Interstitial Cells Testosterone

  32. Hormonal Control of Spermatogenesis FSH Testosterone Sertoli Cells Inhibin Spermatogenesis

  33. Feedback Inhibition Hormonal Control of Spermatogenesis Inhibin Acts on anterior pituitary Inhibits FSH production Testosterone Acts on hypothalamus Inhibits GnRH production

  34. Some Other Effects of Testosterone • Muscle and bone growth • Facial and pubic hair growth • Thickening of vocal cords • Growth of pharyngeal cartilage • Hair follicle effects • Stimulates sebaceous glands • Increased BMR

  35. MALE STERILIZATION Vasectomy

  36. Male • Testes • Produce 2-4 million sperm every day • Outside body – why? • Sperm like temps 1-2 cooler than body temp • Vas Deferens • Tube sperm travel through • Vasectomy (Sterilization) • Cut/tie off tube – sperm can’t get out!

  37. Semen • Contains • 300-500 million sperm • Sperm food • pH buffers • Allows sperm to survive for a couple of days inside female’s body (hostile environment)

  38. Prostate Gland • Adds non-sperm stuff to semen • pH buffers • Nourishment • Cancer very common • Slower-growing (usually) • Surgery for removal

  39. Bulbourethral gland • Adds lubricant to aid travel of semen through the urethra

  40. Female Reproductive System

  41. Females • Ovaries • 2 pouches • Contain ova • Born with all of her eggs (~ 400,000) • Use up ~500 • Won’t run out! • Ovulation • One egg released from ovary to oviduct (fallopian tube)

  42. Female Reproductive System ovary fimbriae cervix vagina l. majora

  43. Internal reproductive: • Vagina • Cervix • Fallopian tube (uterian tube/oviducts) • Fimbrae • Ovary • Uterus • Endometrium • Myometrium • Perimetrium uterus uterine tube ovary endometrium fimbriae myometrium perimetrium cervix vagina

  44. Fimbrae & Fallopian Tube

  45. After Ovulation • Egg pushed along by cilia • Few days travel time to arrive in uterus • Cervix – Opening between uterus & vagina • Normally tiny • At birth – muscles pull open (dilation) cervix to allow baby to pass through = Labor

  46. Menstrual Cycle • Complex combination of many chemicals (hormones) • Usually one egg once a month is released • All about timing!!! • Uterus must be ready in case if the egg gets fertilized • If no fertilization occurs, lining of uterus tears down and rebuilding of the layer for next month occurs.

  47. Chemicals (hormones) • Regulate events in the body • Estrogen • Progesterone • LH (leuteinizing hormone) • FSH (follicle stimulating hormone) • Many others

  48. After Ovulation • Egg pushed along by cilia • Few days travel time to arrive in uterus • Cervix – Opening between uterus & vagina • Normally tiny • During child birth – muscles pull open (dilation) cervix to allow baby to pass through = Labor or parturition

  49. Oogenesis in the Ovary

  50. Oogenesis • Ovary- contains 400,000 oocytes; release about 500 in a lifetime • Ovary- under influence of FSH. The follicles mature every 28 days • Primary follicle produces estrogens • And primary oocyte completes its 1st division produces 2ndary oocyte and polar body

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