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Chapter 20: The Male and Female Reproductive Systems

Chapter 20: The Male and Female Reproductive Systems. Reproduction. Asexual (nonsexual) One-celled organisms Divide themselves Sexual Males and females Specialized sex cells (germ cells or gametes) Male are spermatozoa (sperm cells) Female are ova (egg cells). Meiosis.

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Chapter 20: The Male and Female Reproductive Systems

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  1. Chapter 20:The Male and Female Reproductive Systems

  2. Reproduction • Asexual (nonsexual) • One-celled organisms • Divide themselves • Sexual • Males and females • Specialized sex cells (germ cells or gametes) • Male are spermatozoa (sperm cells) • Female are ova (egg cells)

  3. Meiosis • Cell division process • Halves the number of chromosomes in cell • Produces gametes • Human gametes have 23 chromosomes

  4. The Male Reproductive System • Two groups of organs • Primary • Gonads (testes) • Accessory • Ducts • Exocrine glands

  5. Male reproductive system. Organs of the urinary system are also shown.  

  6. The Testes • Located outside the body proper • Scrotum • Inguinal canal • Testes descend down the abdominal wall into the scrotum through this canal • Spermatic cord • Suspends the testes

  7. Figure 20-2 Descent of the testes.

  8. Internal Structure • Specialized tissue in testis • Seminiferous tubules • Cells develop into spermatozoa • Sustentacular cells • Nourish and protect the spermatozoa • Interstitial cells • Secrete testosterone

  9. Structure of the testis.

  10. Testosterone • Male sex hormone functions • Develops and maintains reproductive structures • Develops spermatozoa • Develops secondary sex characteristics • Deeper voice • Broader shoulders • Narrower hips • More muscle tissue • More body hair

  11. The Spermatozoa-sperm • Individual cells manufactured in seminiferous tubules • Head • Nucleus • Acrosome • Midpiece • Mitochondria • Tail (flagellum)

  12. Diagram of a human spermatozoon.

  13. Accessory Organs • System of ducts that transports spermatozoa • Tubules • Inside testes which collect in the epididymis • Ductus deferens (vas deferens) joins seminal vesicle to form the ejaculatory duct

  14. Semen Mixture of sperm and secretions from various organs • pH 7.2-7.8* • Seminal vesicles • Seminal fluid large part of semen volume • Prostate gland-inferior to urinary bladder, surrounds first part of urethra • Assists in neutralizing vaginal pH • Bulbourethral glands (Cowper glands)-lubricate tip of penis

  15. The Urethra and Penis Urethra • Carries urine from bladder • Carries reproductive cells outside body Penis • Corpus spongiosum • Contains urethra • Corpus cavernosum • Area which contains most of the blood supply during an erection • Glans penis • Prepuce (foreskin) • circumcision

  16. Cross-section of the penis.

  17. Ejaculation • Reflex centers in spinal cord initiate process • Smooth muscle contraction in prostate • Skeletal muscle contraction in pelvic floor • Forceful expulsion of semen through urethra to outside

  18. Hormonal Control of Male Reproduction • Anterior pituitary produces hormones that control testes • Follicle-stimulating hormone (FSH) • Promotes spermatozoa formation • *Luteinizing hormone (LH) • Stimulates testosterone development • Aids sperm cell development

  19. The Effects of Aging on Male Reproduction • Decreasing • Testosterone production • Spermatozoa production • Prostate secretions • Seminal vesicle secretions

  20. The Female Reproductive System • Ovaries (female gonads) • Uterus • Passageways • Oviduct (fallopian tube or uterine tube) • External genital organs

  21. Female reproductive system. The enlargement (right) shows ovulation. 

  22. The Ovaries • Located in pelvic abdomen • Held by ligaments • Broad, ovarian ligaments • Attached to uterus and body wall

  23. The Ova and Ovulation • Ovarian follicle (graafian follicle) • Holds ripening ova • Secretes estrogen • Ruptures to discharge egg cell (ovulation) • Oviduct • Tube that leads to uterus

  24. Microscopic view of the ovary.

  25. The Corpus Luteum • Formed from remains of follicle after ovum is expelled • Secretes estrogen and progesterone • Usually shrinks and is replaced by scar tissue • Remains active during pregnancy

  26. Accessory Organs • In females • Oviducts • Uterus • Vagina • Greater vestibular glands • Vulva and perineum

  27. The Oviducts • Extend from near ovary to uterus • Not connected to ovary • Fimbriae produce current that sweeps ova into oviduct • Cilia in tube lining and peristalsis of tube move ova

  28. The Uterus • Organ where fetus develops to maturity • Corpus • Body, wider, upper portion • Cervix • Neck • Fundus • Supporting ligaments • Myometrium • Muscular wall • Endometrium • Specialized epithelium lining

  29. The Vagina • Distal part of birth canal that opens to outside of body • Fornix • Posterior fornix • Cul-de-sac (rectouterine pouch or pouch of Douglas) • Hymen • Greater vestibular (Bartholin) glands • Mucus producing cells

  30. Female reproductive system (sagittal section).

  31. The Vulva and the Perineum • External parts of female reproductive system • *Vulva • Labia • *Clitoris • Related structures • Obstetrical perineum

  32. External parts of the female reproductive system.

  33. The Menstrual Cycle • Controlled by pituitary hormones regulated by hypothalamus • Cyclic pattern • Regulated by hormonal feedback • Averages 28 days

  34. The menstrual cycle.

  35. Beginning of the Cycle • Several follicles in ovary begin to develop • Increased production of estrogen • Thickens endometrium • Elongates uterine secretion glands • Inhibits release of FSH • Stimulates pituitary to release LH

  36. Ovulation • LH surge in blood • Causes ovulation • Transforms ruptured follicle into corpus luteum that produces estrogen and progesterone • Endometrium thickens • Proliferative phase • Glands and blood vessels increase in size • FSH and LH are inhibited • Follicular phase occurs prior to ovulation

  37. The Menstrual Phase • If ovum is not fertilized, corpus luteum degenerates • Estrogen, progesterone levels decrease • Endometrium degenerates, produces menstrual flow • Endometrium begins to repair itself • FSH released from anterior pituitary to restart cycle

  38. Menopause • Menstruation ceases usually 45-55 years of age • Normal ovarian function declines • Follicles stop ripening • No appreciable amounts of estrogen produced • Uterus, oviducts, vagina, vulva become somewhat atrophied • Vaginal mucosa becomes thinner, dryer, more sensitive

  39. Hormone Replacement Therapy • Combination of estrogen with synthetic progesterone • prescribed to relieve menopause discomfort • Increases breast cancer risk • Increases thrombosis and embolism risk • Risks increase with duration of therapy

  40. Birth Control • Hormonal methods for women • Male contraceptive pill still under investigation • Barrier methods • *ECP-taken 72 hours after intercourse in two doses 12 hours apart • *Mifepristone (RU486) (morning-after pill for emergency contraception • Fertility awareness

  41. Hormone Replacement Therapy • Combination of estrogen with synthetic progesterone prescribed to relieve menopause discomfort • Increases breast cancer risk • Increases thrombosis and embolism risk • Risks increase with duration of therapy

  42. Figure 20-12 Surgical sterilization.

  43. Figure 20-13 Insertion of a female condom.

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