MALE REPRODUCTIVE SYSTEM

1. MALE REPRODUCTIVE SYSTEM

2. Why do men have nipples? • We all start off as females! • Then the Y chromosome kicks in. • Causes the male characteristics to develop in the womb. By then, the nipples have already formed. • FUN FACT • Lions have sex every 15 minutes for an entire week. However, this only occurs every two years. The pig has the longest orgasm; it can last up to 15 minutes.

3. Fun Facts: THINGS YOU PROBABLY DIDN'T KNOW ABOUT YOUR BODY • The average man's penis is three times the length of his thumb.Human thighbones are stronger than concrete.A woman's heart beats faster than a man's.Women blink twice as often as men.The average person's skin weighs twice as much as their brain.Your body uses 300 muscles to balance itself when you are standing stillIf saliva cannot dissolve something, you cannot taste it.Women reading this will be finished nowMen who read this are probably still busy checking their thumbs

4. The Male Reproductive System Figure 24.1

5. The Scrotum – Containing the Testes and Spermatic Cord Figure 24.2

6. EMBRYONIC DEVELOPMENT OF THE SCROTUM • 7 Months in utero • The testis (singular is testis, plural is testes) is retroperitoneal, located up high, above the pubic symphysis. • The vas deferens is a tube that grows from it on the superior edge. On its inferior edge, a fibrous band called the GUBERNACULUM is attached to the testes and inserts onto the skin under where the penis is developing.

7. 7 Months Parietal peritoneum Perineum

8. 8 Months • The gubernaculum shrinks, and testes are pulled down. • The perineum forms a pouch called the VAGINAL PROCESS.

9. 8 months

10. Birth • The vaginal process is pinched off, forming the TUNICA VAGINALIS. • In the meantime, the vas deferens grows upward and into the abdominal cavity. • The DARTOS MUSCLE (cutaneous) lines the scrotum, and blends with the CREMASTER MUSCLE. • The Dartos and cremaster muscles both elevate the testes in the cold so they can stay warm, and they relax in the heat to allow the testes to descend to stay cool.

12. Decent of the Gonads Figure 24.29a-c

13. Spermatic Cord • Vas deferens (ductus deferens) • Cremaster muscle • Spermatic (testicular) artery and vein • Pampiniform plexus (Nerves and lymphatic vessels).

14. The Male Reproductive System • The scrotum – skin and superficial fascia surrounding the testes • Positioning provides an environment cooler than body temperature.

15. Testes • The testes are the primary sex organs in the male, not the penis, because they make testosterone, which creates the male secondary sex characteristics. • Secondary sex characteristics are deep voice, facial hair, axillary and pubic hair, larger musculo-skeletal mass, thyroid cartilage. • In order for sperm to be produced, the temperature has to be 3˚ cooler than normal body temperature. • To insure this lower temperature, the testes are located outside of the body, in the scrotum (outside of the pelvis).

16. Problems at Birth • 1. CONGENITAL INGUINAL HERNIA • The vaginal process doesn’t close off completely, and a piece of intestine protrudes through the inguinal canal. Adults can get inguinal hernias too. • INGUINAL HERNIA • Inguinal hernias in adults are very common (lifetime risk 27% for men, 3% for women), and their repair is one of the most frequently performed surgical operations. • If you do heavy lifting, it increases the abdominal pressure, and a piece of intestine gets pushed into the inguinal canal. Requires surgery to stich the fascia shut.

18. Inguinal Hernia

20. Problems at Birth UNDESCENDED TESTES Is when the gubernaculum does not pull the testes all the way down into the scrotum. Sperm will still be able to exit from the body, male sex hormones will still circulate in the body, and the testes will still have adequate blood supply. However, viable sperm will not be produced. Needs a surgery to pull them down.

22. Undescended Testes • In newborn boys, inguinal canal is still wide open, and if they are cold, testes will disappear up there. This is not the same thing as having undescended testes. You have to check for undescended testes in a warm environment. • As they get older, the testes sometimes pull up with age (have to check for undescended testes again before puberty). • To check for problems with the testes going back up into the abdomen, the doctor feels the scrotum, and asks the patient to cough. Should be a little movement, but the testes should not move all the way up.

23. Structure of the Testes • The testes are enclosed in a serous sac – the tunica vaginalis • Deep to that is the tunica albuginea – fibrous capsule of the testes • Divides each testis into 250-300 lobules • Lobules contain 1-4 coiled seminiferous tubules

24. The Testes Figure 24.3a

25. The Seminiferous Tubules • Seminiferous tubules • They are each 70 cm (2 feet) long. • All together, they stretch out to ½ a mile! • Function of seminiferous tubules is to make sperm. • Spermatogenic cells – sperm-forming cells • Sertoli (Nurse) cells – support cells

26. Spermatogenesis • Spermatogenesis – sperm formation • Begins at puberty – 100 million sperm per day • 1,000 sperm per second are made • 500 billion sperm in a lifetime • Each sperm cell contains 30,000 genes, and each genetic code is slightly different • Cells differentiate and move toward the lumen • Stage 1 – replication of spermatocytes • Stage 2 – meiosis • Stage 3 –Spermatids differentiate into spermatozoa

27. Spermatogenesis Figure 24.4b

28. SPERMATOGENESIS • SPERMATOCYTES divide into more cells which migrate down toward the lumen, grow a tail (now they are called SPERMATIDS), and get released into the lumen. • When they are released and are free-swimming, they are then called SPERMATOZOA.

29. Spermatocytes • 100 million sperm cells are produced each day. • You need that many; below 70 million per ejaculate is considered infertility. • Sperm cells are the smallest cells of the body, but large in numbers.

30. Seminiferous Tubule

32. Sertoli cells (“Nurse cell”) • Surround spermatocytes • Their function is to nurture the developing spermatocytes. • They produce hormones that direct spermatogenesis. • Once meiosis has occurred and the spermatocytes are haploid, they are vulnerable to phagocytosis. The Sertoli cells protect them from this.

33. Spermatids Sertoli cells

34. Interstitial Cells (Leydig cells) • Between the seminiferous tubules are groups of cells called INTERSTITIAL CELLS, which produce testosterone. • They are stimulated by luteinizing hormone, while the spermatocytes are stimulated by FSH.

35. Interstitial cells

36. Testes Slide Interstitial Cells (make testosterone)

37. Fun Fact • One teaspoon of semen contains 300 million sperm. • Human males have enough sperm cells in 5 ml of semen to fertilize the number of eggs equal to 5x the population of the USA. • 60% of the sperm cells are imperfect and can never make it to the egg. They might have multiple flagella that do not propel them forward.

38. Fun Fact • Boy Or Girl? It's In The Father's Genes • Men inherit a tendency to have more sons or more daughters from their parents. • This means that a man with many brothers is more likely to have sons, while a man with many sisters is more likely to have daughters.

39. Fun Fact • What animal produces the most semen? • The Sperm Whale • Produces 100 gallons of semen per ejaculate!

41. Epididymis • The seminiferous tubules come together to form the EPIDIDYMIS, the tube of which is 5 meters (the width of this room!). • The function of the epididymis is to allow sperm to mature and to store them. • It takes 20 days for the sperm to go from production to storage. • If sperm is not ejaculated, it will just die and be phagocytized. • The epididymis has smooth muscles for peristalsis during ejaculation to move the sperm along.

42. The Epididymis Tube leading out of the epididymis Figure 24.3a

43. Spermatic Cord • The SPERMATIC CORD leaves the epididymis and contains the spermatic artery, vein, nerves, and the DUCTUS (VAS) DEFERENS which is the tube that carries the sperm out of the epididymis. • The Vas deferens is long, 45cm (2 feet). • It goes through the inguinal canal, loops around urinary bladder and down the other side.

44. The Ductus (Vas) Deferens Figure 24.1

45. The Spermatic Cord Figure 24.2

46. Seminal Vesicles • Posterior to the urinary bladder are the SEMINAL VESICLES • The EJACULATORY DUCT meets up with the PROSTATIC URETHRA in the prostate.

47. Seminal Fluid • The functions of the seminal vesicles (60%) and the prostrate (40%) are to produce most of the seminal fluid (seminal fluid plus sperm = semen).

48. Functions of the Semen • Medium for sperm to swim in • Nutrients for sperm (fructose, NOT sucrose or glucose) • Neutralizes acidity in vagina to allow sperm to survive

49. Prostate • The urethra goes through the middle of the prostate, and the prostate continues to grow throughout life. • PROSTATIC HYPERTROPHY • Can constrict the urethra, causing retention of urine because it is hard to urinate. Needs surgery to open.

50. Terms • Urinary retention • When the urine cannot get out. • Usually due to prostatic hypertrophy. • Urinary incontinence • When the urine comes out involuntarily. • Usually due to incompetent urethral sphincter. • The person may need to wear adult diapers.