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ADVANCED PHYSIOLOGY

ADVANCED PHYSIOLOGY. REPRODUCTION. Instructor Terry Wiseth. Male System. Testes paired oval bodies about 1.5 in long. Tunica Albuginea. Outer covering white fibrous connective tissue. Tunica Vaginalis. Inner covering visceral peritoneum. Testes Development.

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ADVANCED PHYSIOLOGY

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  1. ADVANCED PHYSIOLOGY REPRODUCTION Instructor Terry Wiseth

  2. Male System • Testes • paired oval bodies • about 1.5 in long

  3. Tunica Albuginea • Outer covering • white fibrousconnective tissue

  4. Tunica Vaginalis • Inner covering • visceral peritoneum

  5. Testes Development • Develop in the abdominal cavity • descend through the inguinal canal into the scrotum before birth • lower temperature necessary for spermatogenesis

  6. Temperature • Normal body temperature is too hot thus is lethal to sperm • so the testes are outside of the abdominal cavity • where the temperature is about 2° C (3.6° F) lower

  7. Temperature • a woman’s body temperature is lowest around the time of ovulation • to help insure sperm live longer to reach the egg • If a man takes too many long, very hot baths • sperm count can be reduced

  8. Scrotal Sac • Divided into lobules • containing coiled seminiferous tubules • empty into a central network of tubules called the rete testis

  9. Cellular Components • Interstitial Cells • Sertoli Cells

  10. Interstitial Cells • Leydig Cells • lie between seminiferous tubules • Secrete testosterone

  11. Sertoli Cells • in lower epithelial layers within seminiferous tubules • Form blood-testes barrier • cells joined by tight junctions

  12. Sertoli Cells • Supply nutrients to spermatids • Secrete inhibin • depresses FSH production • Secrete androgen-binding protein (ABP) • concentrates androgens in tubules • Secrete Müllerian-inhibiting factor (MIF) • involved in testes descent

  13. Spermatogenesis • production of sperm • requires 9 weeks

  14. Spermatogonia • 2N stem cells form basal layer of the seminiferous tubule • Separated by blood-testis barrier from spermatocytes which contain different membrane antigens • Mitotically divide toform primaryspermatocytes

  15. Primary Spermatocytes • 1N cells • Undergo meiosis I (reduction division) to form two haploid secondary spermatocytes

  16. Secondary Spermatocytes • 1N cells • Complete meiosis II to form four haploid spermatids connected by cytoplasmic bridges

  17. Spermatids • 1N • Undergo structural change (spermiogenesis) to form spermatozoa

  18. Sperm • 1N • Head contains nucleus and acrosomal cap containing enzymes • Midpiece contains two centrioles + microtubules, mitochondrial spiral • Tail contains flagellum surrounded by fibrous sheath

  19. Spermatogenesis

  20. Epididymis • long coiled tube • about 18-20 ft long • Composed of head, body and tail • Receives sperm from the rete testis

  21. Epididymis Functions • Sperm storage and maturation • Recycles damaged sperm • Prevents premature capacitation

  22. Ductus Deferens • vas deferens • tube continuous with the epididymis • Carries sperm to the seminal vesicle from the testes

  23. Vasectomy • involves making a small slit in each scrotum • cutting the vas deferensnear where they begin • tying off the cut ends toprevent sperm fromleaving the scrotum • not designed to be areversible operation

  24. Vasectomy

  25. Vasectomy

  26. Spermatic Cord • composed of: • ductus deferens • testicular arterytesticular vein • lymphatics • nerves wrappedwith connective tissue

  27. Spermatic Cord • extends from testes to the deep inguinal ring • In abdominal cavity the ductus deferens curves posterior to the bladder • Expands to form the ampulla and joins the duct of the seminal vesicle

  28. Seminal Vesicles • pouch-like glands that empty into the ductus deferens at the ejaculatory duct • Secrete viscous alkaline fluid that constitutes about 60% of semen

  29. Seminal Fluid • Fluid contains: • Fructose • for ATP production for sperm • Alkaline • Neutralizesacid in femalereproductivesystem

  30. Seminal Fluid • Fluid contains: • Prostaglandins • Increases sperm motility and viability • decrease mucous viscosity at cervix • stimulate female uterine contractions to move the semen up into the uterus • Semenogelin • causes spermcoagulation afterejaculation

  31. Capacitation • Sperm become motile when mixed with seminal fluid • Secretions of female tract make sperm capable of fertilization

  32. Ejaculatory Duct • short duct extends from the ductus deferens to urethra

  33. Prostate Gland • large gland surrounds prostatic urethra and ejaculatory ducts • Secretes thin white slightly acidic fluid • about 25% of semen

  34. Prostate Enlargement • The prostate needs a lot of zinc to function properly • insufficient dietary zinc can lead to enlargement • potentially can constrict the urethra to the point of interfering with urination

  35. Prostate Surgery • Mild cases of prostate hypertrophy can often be treated by adding supplemental zinc to the man’s diet • severe cases require surgical removal of portions of the prostate • if not done very carefully can lead to problems with urination or sexual performance

  36. Prostate Fluid • Fluid contains: • Citrate • for ATP production in Kreb's cycle • Proteolytic enzymes • liquefy coagulated semen after15-20 minutes in vagina • Acid phosphatase • function unknown • Seminal plasmin • antibiotic, destroys bacteria

  37. Prostate Fluid • Prostate secretions are alkaline to buffer: • residual urine which tends to be acidic • the acidity of thewoman’s vagina

  38. Bulbourethral Glands • Cowper's gland • pea-size • posterior and lateral to membranous urethra

  39. Bulbourethral Fluid • bulbourethral fluid is secreted just before emission of the semen • alkaline mucoid • neutralizes acid • coats and lubricatesurethra prior tosemen passage

  40. Urethra • conducts urine or sperm away from the body • Urethra leads the length of the penis

  41. Urethra • conducts urine or sperm away from the body • Urethra leads the length of the penis

  42. Penis • 3 cylindrical columns of erectile tissue • In relaxed state the central arteries are constricted reducing inflow

  43. Penis • In excited state the central arteries dilate (PNS) • blood fills the vascular channels causing an erection and compresses the veins reducingvenous outflow

  44. Arousal • arteries become filled with blood from the arteries that supply them and the pressure seals off the veins that drain these areas causing an erection • necessary for insertion of the penis into the woman’s vagina

  45. Glans Penis • The head of the penis • very sensitive to stimulation • covered by the foreskin or prepuce

  46. Circumcision • Removal of prepuce • Medically, circumcision is not a necessity • rather a cultural “tradition”

  47. Circumcision • Males who have not been circumcised need to keep the area between the glans and the prepuce clean • Prevents microorganism growth on accumulated secretions

  48. Circumcision • evidence that uncircumcised males who do not keep the glans/prepuce area clean • slightly more prone to penile cancer

  49. Ejaculation • Ejaculation is a sympathetic reflex causing peristaltic waves • extending from the ductus deferens to the penis • the bladder sphincteris closed

  50. Male Sexual Development • Genetic • XX chromosomes are female • XY are male, male determines offspring sex in humans

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