1. Chapter 16 The Reproductive System
Essentials of Human Anatomy & Physiology
Seventh Edition
Elaine N. Marieb
Chapter 16 The Reproductive System
Slides 16.1 – 16.20
Lecture Slides in PowerPoint by Jerry L. Cook
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

2. Functions: 1. Produce Gametes 2. Transport Gametes 3. Maintain Gametes
4. Maintain developing Zygote / Fetus (female)
5. Produce Sex hormones:
Male = testosterone
Female = estrogen and progesterone

3. MALE REPRODUCTIVE SYSTEM INTERESTING FACTS
 Male sperm are significantly smaller than the female egg.  While the sperm measures 2.5 to 3.5 microns across the head the fully mature egg is microns in diameter.
About 500 million sperm mature every day in a healthy male.
The male scrotum hangs outside the body since the internal body temperature is too high and will kill the sperm.
Once the sperm has penetrated the egg the outer shell becomes impenetrable to other sperm
Unlike the ovaries which never produce new eggs after a female child is born, the male testes (once sperm production begins in puberty), can produce about 1,000 sperm per second, or about 30 billion per year. From the standpoint of the mathematics alone, ejaculations of semen hold enough sperm to populate the earth!

4. MALE REPRODUCTIVE SYSTEM INTERESTING FACTS
Sperm cells contain receptors on the surface of the sperm head that are similar to odor receptors in the nose. This has lead researchers to believe that sperm can detect the "odor" of the released egg, and literally are following its scent to locate it and attempt to fertilize it.
It was once thought that the best time to either have sex to get pregnant, or to abstain from sex to keep from getting pregnant was at the time of ovulation. In reality, the best time to have sex if one to two days before ovulation, so that sperm cells have enough time to swim up through the uterus and the fallopian tubes to be waiting for the egg when it is ejected from the ovary at ovulation. Following ovulation, changes in a woman's hormones produce changes in the secretions at the cervix (the opening to the uterus, at the blind end of the vagina), and these thicken to form a barrier intended to protect the potentially developing embryo (if the egg has been fertilized). It is extremely difficult for sperm to penetrate this mucus barrier, and therefore more difficult for the egg to be fertilized after ovulation has occurred.

5. The Reproductive System
Gonads – primary sex organs
Testes in males
Ovaries in females
Gonads produce gametes (sex cells) and secrete hormones
Sperm – male gametes
Ova (eggs) – female gametes
Slide 16.1
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

6. Meiosis Make sex cells through process called Meiosis:
In humans each body (somatic cell) has 46 chromosomes = diploid
Sex cells are haploid (23 chromosomes)
Meiosis = type of cell division that reduces the chromosomes # in half so that during fertilization, get correct amt. of chromosomes.
This process occurs in two divisions

7. Male Reproductive System
Testes:
Produce sperm and male sex hormones
Accessory Organs forming Male Duct System {Transports sperm}:
Epididymis
Ductus deferens
Urethra
Slide 16.2a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

8. Male Reproductive System
Accessory organs:
Seminal vesicle
Prostate gland
Bulbourethral gland
External genitalia:
Penis
Scrotum
Slide 16.2b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

9. Male Reproductive System
Figure 16.2
Slide 16.2c
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

10. Testes Coverings of the testes
Tunica albuginea – capsule that surrounds each testis
Figure 16.1
Slide 16.3a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

11. Testes Coverings of the testes (continued)
Septa – extensions of the capsule that extend into the testis and divide it into lobules
Figure 16.1
Slide 16.3b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

12. Testes Each lobule contains one to four seminiferous tubules:
Tightly coiled structures
Function as sperm-forming factories
Empty sperm into the rete testis
Sperm travels through the rete testis to the epididymis
Interstitial cells produce androgens such as testosterone
Slide 16.4
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

13. Epididymis Comma-shaped, tightly coiled tube – 20 ft. long
Found on the superior part of the testis and along the posterior lateral side
Functions to mature and store immature sperm cells (trip takes at least 20 days)
Expels sperm with the contraction of muscles in the epididymis walls to the vas deferens
Slide 16.5
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

14. Ductus Deferens (Vas Deferens)
Carries sperm from the epididymis to the ejaculatory duct
Passes through the inguinal canal and over the bladder
Moves sperm by peristalsis
Spermatic cord – ductus deferens, blood vessels, and nerves in a connective tissue sheath (fig. 16.1)
Slide 16.6a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

15. Ductus Deferens (Vas Deferens)
Ends in the ejaculatory duct which unites with the urethra
Site of Vasectomy
Vasectomy – cutting of the ductus deferens at the level of the testes to prevent transportation of sperm
Slide 16.6b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

16. Urethra
Extends from the base of the urinary bladder to the tip of the penis
Carries both urine and sperm
Sperm enters from the ejaculatory duct
Slide 16.7a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

17. Urethra Regions of the urethra
1. Prostatic urethra –surrounded by prostate
2. Membranous urethra – from prostatic urethra to penis
3. Spongy (penile) urethra – runs the length of the penis
Slide 16.7b

18. Seminal Vesicles Located at the base of the bladder
Produces a thick, yellowish secretion = alkaline fluid rich in nutrients (60% of semen)
Fructose (sugar)
Vitamin C
Prostaglandins
Other substances that nourish and activate sperm
Slide 16.8
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

19. Prostate Gland
Encircles the upper part of the urethra, below the bladder
Secretes a milky, alkaline, fluid
Helps to activate sperm motility
Enters the urethra through several small ducts
Slide 16.9
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

20. Bulbourethral Glands Pea-sized gland inferior to the prostate
Produces a thick, clear mucus for lubrication:
Cleanses the urethra of acidic urine
Serves as a lubricant during sexual intercourse
Secreted into the penile urethra
Slide 16.10
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

21. Semen Mixture of sperm and accessory gland secretions
Only 2-5 ml (teaspoon) of sperm is made during ejaculation: however, there are b/w 50 – 130 million per ml.
Advantages of accessory gland secretions:
Fructose provides energy for sperm cells
Alkalinity of semen helps neutralize the acidic environment of vagina
Semen inhibits bacterial multiplication
Elements of semen enhance sperm motility
Slide 16.11
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

22. SEMEN*
Contains sperm cells (FROM TESTES), alkaline fluid (FROM PROSTATE), fructose (FROM SEMINAL VESICLE), & lubricant (FROM BULBOURETHRAL)

23. Infertility Male infertility may be caused by:
obstructions of the duct system
Hormonal imbalance
Environmental estrogens
Pesticides
Excessive alcohol
Semen analysis is one of the first series of tests done when couples are unable to conceive: look at sperm count, pH, volume, fructose content, etc.
Sperm count lower than 20 million per ml makes impregnation improbable

24. External Genitalia Scrotum Divided sac of skin outside the abdomen
Maintains testes at 3°C lower than normal body temperature to protect sperm viability
The Cremaster muscle is an extension of the internal oblique muscle that elevates the scrotum during sexual arousal and exposures to the cold
Slide 16.12
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

25. External Genitalia Penis
Delivers sperm into the female reproductive tract
Regions of the penis:
Shaft
Glans penis (enlarged tip)
Prepuce (foreskin)
Folded cuff of skin around proximal end
Often removed by circumcision
Slide 16.13a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

26. External Genitalia
Internally there are three areas of spongy erectile tissue around the urethra
Slide 16.13b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

27. Spermatogenesis Production of sperm cells
Begins at puberty and continues throughout life
Occurs in the seminiferous tubules
Slide 16.14
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

28. Processes of Spermatogenesis
Sperm cells are produced from spermatagonia cells, which contain 46 chromosomes (diploid)
Spermatogonia (stem cells) undergo rapid mitosis to produce more stem cells before puberty
Follicle stimulating hormone (FSH) modifies spermatogonia division:
One cell produced is a stem cell
The other cell produced becomes a primary spermatocyte
Slide 16.15a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

29. Processes of Spermatogenesis
Primary spermatocytes undergo meiosis
Haploid spermatids are produced
Slide 16.15b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

30. Processes of Spermatogenesis
Spermiogenesis
Late spermatids are produced with distinct regions
Head – contains DNA covered by the acrosome
Midpiece
Tail
Sperm cells result after maturing of spermatids
Spermatogenesis takes 64 to 72 days
Slide 16.16
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

31. Processes of Spermatogenesis
Spermatogonium (46 chromosomes) duplicates its DNA (mitosis). This gives rise to:
One primary spermatocyte (46 chromosomes) which undergoes Meiosis I. Other stays at membrane as stem cell:
This gives rise to 2 spermatocytes (46 chromosomes) which undergo Meiosis II
This produces 4 spermatids (23 chromosomes) Then these cells mature into:
Four sperm cells that collect in the lumen of the seminiferous tubule
Sperm travel to, fully mature, and are stored in the epididymis
Figure 16.3
Slide 16.17

32. Spermatogenesis http://www.youtube.com/watch?v=k2kclHg0ohU

33. Sperm
Many things can suppress sperm production or mutate the sperm (2 heads / 2 tails. . . ):
Antibiotics (penicillin)
Radiation
Lead
Pesticides
Marijuana
Tobacco
Excessive Alcohol

34. Anatomy of a Mature Sperm Cell
The only human flagellated cell
DNA is found in the head
Acrosome  similar to lysosome, when comes into contact with egg, membrane breaks down and releases enzyme to allow it to penetrate
Figure 16.5
Slide 16.18
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

35. Sperm Penetrating Egg
&NR=1&feature=endscreen 8

36. Hormonal Control of Male Reproductive Function
puberty, hypothalmus secretes a “releasing hormones” that target the male’s pituitary gland:
2. This pituitary gland secretes 2 gonadotropins:
Follicle Stimulating hormone (FSH)  stimulates spermatogenesis in the seminiferous tubules
Luteinizing Hormone (LH)  stimulates the interstitial cells between the seminiferous tubules to produce male sex hormones (testosterone)

37. Testosterone Production
Male Sex hormones = Androgens
The most important hormone of the testes = testosterone
Produced in interstitial cells  production puberty
Slide 16.19a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

38. Testosterone Production
Functions of testosterone:
Stimulates reproductive organ development
Underlies sex drive
Causes secondary sex characteristics:
Deepening of voice  affects vocal cords
Increased hair growth
Enlargement of skeletal muscles
Thickening of bones
Slide 16.19b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

39. Regulation of Male Androgens (Sex Hormones)
Figure 16.6
Slide 16.20
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

40. Male Reproduction Disorders
1. Priapism  persistent, painful erections lasting 4+ hours. Not associated with sexual activity and is not relieved from an orgasm. Occurs when blood flows into penis, but is not adequately drained.
Causes = alcohol or drug abuse, medication, spinal cord problems or injuries, anesthesia, blood diseases . . .
2. Balantis  inflammation of the head of the penis.
Often occurs in men and boys who have not been circumcised and who have poor hygiene. Sweat, dirt, and bacteria build and cause foul smell that accumulates under the foreskin.
3. Chriptorchidism  male testes and female ovaries during development are made in the approximately same location of the abdomen; however, testes descend into the outer scrotum: failure of this descent = this condition. If untreated, can lead to sterility, surgery can rectify this problem.
4. Prostate Cancer cancer that starts in the prostate. As men age (see in men 75+, rare to see in 40’s), their prostate enlarges and is called benign prostatic hyperplasia (BPH)  this can increase your PSA blood test results, not necessarily raise your risk of cancer.
Signs: delayed / slow start of urinary system, dribbling or leaking after urinating, blood in urine or semen, bone pain or tenderness (if cancer has spread)

42. UPDATED RESEARCH ABOUT SPERM:
ws html
ws html