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The Reproductive System and Development Chapter 25 – Lecture Notes

The Reproductive System and Development Chapter 25 – Lecture Notes. to accompany Anatomy and Physiology: From Science to Life textbook by Gail Jenkins, Christopher Kemnitz, Gerard Tortora. Chapter Overview. 25.1 Sperm Production 25.2 Male Reproductive System

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The Reproductive System and Development Chapter 25 – Lecture Notes

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  1. The Reproductive System and DevelopmentChapter 25 – Lecture Notes to accompany Anatomy and Physiology: From Science to Life textbook by Gail Jenkins, Christopher Kemnitz, Gerard Tortora

  2. Chapter Overview 25.1 Sperm Production 25.2 Male Reproductive System 25.3 Female Reproductive System 25.4 Vagina and Mammary Glands 25.5 Ovarian and Uterine Cycle 25.6 Implantation of Blastocyst 25.7 Embryonic to Fetal Period

  3. Chapter Overview 25.8 Maternal Changes During Pregnancy 25.9 Labor 25.10 Milk Production and Ejection

  4. Essential Terms gamete • germ cells with haploid number of chromosomes fertilization • occurs when sperm unites with secondary oocyte pregnancy • sequence of events resulting in birth of child gonads • male testes and female ovaries which secrete hormones and produce gametes

  5. Introduction Sexual Reproduction • Males and females differ anatomically to produce gametes and support a fetus • Fertilization is the result of male and female gametes joining • Pregnancy begins with fertilization and usually results in birth of a child • Gonads produce gametes and hormones

  6. Concept 25.1Sperm Production

  7. Male Reproductive System • Testes – System of Ducts • Epididymis, ductus deferens, ejaculatory ducts, and urethra • Accessory glands • Seminal vesicles, prostate, and bulbourethral glands • Supporting Structures • Scrotum and penis

  8. Figure 25.1a

  9. Figure 25.1b

  10. Scrotum • Scrotal location and muscle contraction regulate temperature of testes • Normal sperm production occurs 2-3°C lower than core body temperature • Response to cool temperatures • Cremaster muscles contract to pull testes close to body • Dartos muscles contract to tighten scrotum • Response to warm temperatures • Reverse of above actions

  11. Figure 25.2

  12. Testes • One testes in each sac of scrotum • Descend during seventh month of fetal development • Tunica albuginea is located deep to tunica vaginalis and forms 200-300 lobules • Lobules contain seminiferous tubules • Spermatogenesis carried out by seminiferous tubules of testes

  13. Figure 25.3a

  14. Figure 25.3b

  15. Figure 25.3c

  16. Testes • Spermatogenic cells • Begin sperm production at puberty • Sertoli or sustentacular cells • Junctions form blood-testis barrier • Nourish spermatogenic cells • Carry out phagocytosis • Control spermatogenic movement • Produce fluid for transport • Secrete hormone inhibin • Leydig (interstitial) cells • Secrete testosterone

  17. Figure 25.4a

  18. Figure 25.4b

  19. Spermatogenesis • Begins with spermatogonia and diploid number of chromosomes • Some pass through blood-testis barrier • Primary spermatocytes also diploid

  20. Figure 25.5

  21. Spermatogenesis • Meiosis I • Crossing-over during metaphase I • Secondary spermatocytes result • Each with haploid number • Meiosis II • Results in four spermatids • Each with haploid number

  22. Spermatogenesis • Cytoplasmic bridges link the four daughter cells • Spermiogenesis • Transformation of spherical spermatids into elongated sperm • Formation of arcosome • Flagellum develop • Mitochondria multiply

  23. Sperm • 300 million per day produced • Survive 48 hours in female reproductive tract • Sperm Parts • Head • Nucleus • Arcosome • Tail • Neck • Middle piece • Principal piece • End piece

  24. Figure 25.6

  25. Hormonal Control of Testes • Negative feedback loops control testosterone release and spermatogenesis • Gonadotropin-releasing Hormone (GnRH) • Increased production at puberty • Stimulates secretion of LH and FSH • Luteinizing hormone (LH) • Stimulates Leydig cells • Follicle-stimulating hormone (FSH) • Stimulates Sertoli cells to secrete ABP

  26. Figure 25.7

  27. Hormonal Control of Testes • Testosterone • Principal androgen • Synthesized from cholesterol • Suppresses LH and GnRH secretion • Converted to DHT in prostate and seminal vesicles • Dihydrotestosterone (DHT) • Stimulates development of external genitals • Androgen-binding Protein (ABP) • Binds to and keeps testosterone levels high • Inhibin • Inhibits FSH secretion

  28. Effects of Testosterone and Dihydrotestosterone • Prenatal development • Development of male sexual characteristics • Development of sexual function • Stimulation of anabolism

  29. Figure 25.8

  30. Concept 25.2Male Reproductive System

  31. Reproductive System Ducts in Males • Ducts of testis • Seminiferous tubules • Straight tubules • Rete testis • Efferent ducts • Ductus epididymis • Epididymis • Site of sperm maturation and storage • Consists of ductus epididymis • Head – superior portion formed by efferent ducts of testis • Body • Tail – continues as ductus (vas) deferens

  32. Ductus Deferens • Terminal portion is the ampulla • Conveys sperm from epididymis toward urethra • Storage and reabsorption of sperm

  33. Figure 25.9

  34. Spermatic Cord • Supporting structure ascends out of scrotum • Comprised of several structures • Ductus deferens • Testicular artery • Pampiniform plexus • Autonomic nerves • Lymphatic vessels • Cremaster muscles

  35. Ejaculatory Ducts • Formed by duct of seminal vesicle and ampulla of ductus deferens • Eject sperm and seminal vesicle secretions from urethra to exterior

  36. Urethra • Shared by reproductive and urinary systems • 3 subdivisions • Prostatic urethra • Membranous urethra • Spongy (penile) urethra

  37. Accessory Sex Glands • Produce fluids to protect semen and facilitate their movement • Seminal vesicles • Prostate • Bulbourethral or Cowper’s glands

  38. Seminal Vesicles • Alkaline fluid • Fructose • Prostaglandins • Clotting proteins • Approximately 60% of semen volume

  39. Prostate Gland • Citric acid • Proteolytic enzymes – prostate-specific antigen (PSA) • Pepsinogen • Lysozyme • Amylase • Hyaluronidse • Milky, acidic fluid (pH ~ 6.5) • Approximately 25% semen volume

  40. Bulbourethral / Cowper’s Glands • Pea sized glands active during sexual arousal • Alkaline fluid • Secrete lubricating mucus

  41. Semen • Combination of sperm and seminal fluid • 2.5 – 5 mL per ejaculation • 50 – 150 million sperm/ml • Alkaline pH ~ 7.2 – 7.7 • Seminalplasmin – antibiotic

  42. Penis • Contains urethra • Passage for sperm and urine • 3 Parts • Root • Body • Glans penis • Erection maintained by parasympathetic fibers • Ejaculation, a sympathetic reflex, releases semen to exterior

  43. Figure 25.10a

  44. Figure 25.10b

  45. Concept 25.3Female Reproductive System

  46. Figure 25.11a

  47. Figure 25.11b

  48. Figure 25.12

  49. Figure 25.13

  50. Figure 25.14a

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