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The Reproductive System

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  1. The Reproductive System Chapter 24

  2. Reproductive System • Unlike other body systems which functions almost continuously the reproductive system is inactive until puberty • The primary sex organs or gonads are the testes in the male and the ovaries in the female

  3. Reproductive System • The gonads produce sex cells, or gamates as well as secreting hormones • The remaining diversion organs of the reproductive system (ducts, glands and external genitalia) are referred to as accessory reproductive organs • Although male and female reproductive organs are quite different they have a common origin and a common purpose to produce offspring

  4. Reproductive System • The male’s reproductive role is to manufacture males gametes called sperm and to deliver them to the female reproductive tract, where fertilization can occur • The mutually complimentary role of the female is to produce female gametes, called ova or eggs.

  5. Reproductive System • When these events are properly timed, a sperm and an egg fuse to form a fertilized egg, the first cell of the new individual, from which all body cells will arise • The male and female reproductive systems are equal partners in events leading up to fertilization • Once fertilization has occurred, the female uterus provides a protective environment for the embryo until birth

  6. Reproductive System • The sex hormones - androgens in males and estrogens and progesterone in females play vital roles in both the development and function of the reproductive organs and in sexual behavior and drives • These hormones also influence the growth and development of many other organs and tissues of the body

  7. Male Reproductive System • The image which follows represents an overview of the male reproductive system

  8. Male Reproductive System

  9. Male Reproductive system • The sperm-producing testes, or male gonads, lie within the scrotum • From the testes the sperm are delivered to the body exterior through a system of ducts in the following order; • Epididymis • Ductus deferens • Urethra

  10. Male Reproductive System

  11. Male Reproductive System • The accessory sex glands, which empty their secretions into the ducts during ejaculation are • Seminal vesicles • Prostrate gland • Bulbourethral glands

  12. Male Reproductive System

  13. The Scrotum • The scrotum is a sac of skin and superficial fascia that hangs outside of the abdominopelvic cavity at the root of the penis

  14. The Scrotum

  15. The Scrotum • Covered with sparse hairs, the scrotal skin is more heavily pigmented than that elsewhere on the body

  16. The Scrotum • The paired testes, or testicles, lie suspended in the scrotum • A midline septum divides the scrotum into right and left halves, one compartment for each testis

  17. The Scrotum • The location of a man’s testes appears to make them vulnerable to injury • However, viable sperm cannot be produced at core body temperature (36.2 C) • The superficial location of the scrotum provides a temperature which is about 3 degrees cooler

  18. Scrotum • The scrotum also responds to temperature changes • When it is cold, the testes are draw closer to the warmth of the body and the scrotum becomes shorter and heavily wrinkled to reduce heat loss • When it is warm, the scrotal skin is flaccid and loose to increase cooling, and the testes hang lower

  19. The Scrotum • These changes maintain a fairly constant temperature and reflect the activity of the two sets of muscles • Dartos • Cremaster

  20. The Testes • Each testes is approximately 4 cm long and 2.5 cm in diameter • It is surrounded by two tunics • Tunica vaginalis • Tunica albuginea

  21. The Testes • The outer tunic is the two layered tunica vaginalis which is derived from the peritoneum • Deep to this is the tunica albuginea, the fibrous capsule of the testis

  22. The Testes • Septa extending from the tunica albuginia divide the testis into 250 - 300 wedge shaped compartments or lobules • Each lobule contains 1-4 semiinferous tubules

  23. The Testes • The seminiferous tubules produce the sperm • The seminiferous tubules of each lobule converge to form a tubulus rectus

  24. The Testes • The tubulus rectus is a straight tubule that conveys sperm into the rete testis • The rete testis is a tubular network from which the sperm leave via the efferent ductules

  25. The Testes • Sperm leaving the efferent ductules enter the epididymis which is located on the external surface of the testis

  26. The Testes • Lying in the soft connective tissue surrounding the seminiferous tubules are the interstitual cells or Leydig cells

  27. The Testes • Interstitial cells produce androgens (most importantly testosterone), which is secreted into the surrounding interstitual fluid • It is significant that the sperm producing and hormone producing functions of the testis are carried out by completely different cell populations

  28. The Testes • The long testicular arteries, which branch from the abdominal aorta, supply the testes

  29. The Scrotum • The testicular veins draining the testes arise from a vinelike network called the pampiniform plexus that surrounds the testicular artery

  30. The Scrotum • The plexus absorbs heat from the arterial blood, cooling it before it enters the testes • Thus, it provides an additional avenue for maintaining the testes at their cool homeostatic temperature

  31. The Testes • The testes are served by both divisions of the autonomic nervous system • Associate sensory nerves transmit impulses • Nerve fibers are enclosed in the spermatic cord

  32. Homeostatic Imbalance • Although testicular cancer is relatively rare (1 in 20,000) it is the most common cancer in young men (15-35) • A history of mumps or orchitis (inflammation) increases the risk • The most important risk factor is cryptochidism (non-descent of the testes) • The most common sign is a painless solid mass in the testes (self-exam)

  33. The Penis • The penis is a copulatory organ designed to deliver sperm into the female reproductive tract

  34. The Penis • The penis and the scrotum which hang from the peritoneum make up the external reproductive structures or genitalia

  35. The Penis • The male perineum is a diamond shaped region located between the public symphysis anteriorly, the coccyx posteriorly, and the ishial tuberosities laterally

  36. The Penis • The floor of the perineum is formed by muscles; • Ishiocavernous • Bulbosponginous • Superficial transverse perineus

  37. The Penis • The penis consists of an attached root and a free shaft or body that ends in an enlarged tip, the glans penis • The skin of the penis is loose, and it slides distally to form a cuff of skin called the prepuce or foreskin around the glans

  38. The Penis • Internally, the penis contains the spongy urethra and three long cylindrical bodies (corpora) of erectile tissue • Erectile tissue is a spongy network of connective tissue and smooth muscle riddled with vascular spaces

  39. The Penis • During sexual excitement, vasular spaces fill with blood causing the penis to enlarge an become rigid • This event, called an erection, enables the penis to serve as a penetrating organ

  40. The Penis • The midventral erectile body, the corpus spongiosum, surrounds the urethra • It expands distally to form the glans and proximally to form the part of the root called the bulb of the penis

  41. The Penis • The bulb is covered externally by the sheetlike bulbospingiosus muscle and is secured to the urogential diaphragm

  42. The Penis • The paired dorsal erectile bodies called the corpora cavernosa make up most of the penis and are bound by fibrous tunica albuginea • Their proximal ends from the crura of the penis and each is surrounded by the ischiocavernosus

  43. The Penis • Each crus is surrounded by an ischiocavernosus muscle and anchors to the pubic arch of the bony pelvis

  44. The Male Duct System • Sperm travel from the testes to the outside of the body through a system of ducts • The accessory ducts are… • Epididymis • The ductus deferens • Urethra

  45. The Male Duct System • The comma-shaped epididymis is about 3.8 cm long • Its head, which joins the efferent ductiles, caps the superior aspect of the testis • Its body and tail regions lie on the posteriolateral aspects of the testis

  46. The Male Duct System • The bulk of the epididymis consists of the highly coiled duct of the epididymis with an uncoiled length of about 6 meters

  47. The Male Duct System • Within the duct of the epididymis some of the cells of pseudostratified epithelium mucosa exhibit long, nonmotile microvilli which absorb excess testicular fluid and pass nutrients to the sperm in the lumen

  48. The Epididymis • The immature, nearly nonmotile sperm that leave the testis are moved slowly through the duct of the epidymis • As the sperm move along the twisting course, a trip of 20 days, the sperm gain the ability to swim

  49. The Epididymis • When a male is sexually stimulated and ejaculates, the smooth muscle in the walls of the epididymis contracts, expelling sperm from its tail section into the next segment of the duct system the ductus deferens • Sperm can stay in the epididymis for several months • If held longer, they are eventually phago-cytized by epithelial cells of the epididymis

  50. The Ductus Deferens • The ductus deferens or vas deferens is about 45 cm (18 in) long • It runs upward as part of the spermatic cord from the epididymis through the inguinal canal into the pelvic