1. The Reproductive System
Chapter 19
The Reproductive System

2. 19-1: Reproductive System
Produces, stores, nourishes, & transports male & female reproductive cells (gametes)
Includes:
Gonads
Ducts for receiving/transporting gametes
Accessory glands & organs
External genitalia

3. Male reproductive system
Gonads (testes) secrete sex hormones (androgens)
Spermatozoa (sperm) transported in semen
Female reproductive system
Gonads (ovaries) release one oocyte (egg) per month
Sperm fuse with the oocyte through fertilization
Uterus supports developing embryo

4. 19-1 Checkpoint Define gamete.
List the basic components of the reproductive system.
Define gonads.

5. 19-2: Male Reproductive System
Male reproductive tract delivers sperm
Epididymis, ductus deferens, ejaculatory duct, urethra
Male accessory organs add secretions
Seminal glands, prostate gland, bulbourethral gland
External genitalia
Scrotum & penis

7. The Testes Testes hang within scrotum
Muscles contract testes closer to body
Testis divided into lobules containing seminiferous tubules
Sperm produced in tubules enter epididymis
Spaces between tubules produce androgens (testosterone)

9. Spermatogenesis Begins with mitosis Continues with meiosis
Spermatogonia undergo mitosis; become spermatocytes
Continues with meiosis
Spermatocytes produce spermatids
Each spermatid contains 23 chromosomes
Finishes with spermiogenesis
Spermatid matures into spermatozoon (sperm cell)
Takes about 9 weeks

10. Anatomy of Spermatozoon
Head contains chromosomes
Covered by acrosome—contains enzymes to penetrate surface of egg
Middle piece contains mitochondria to provide energy
Tail moves sperm cell

12. Male Reproductive Tract
Epididymis
Sperm cells transported to epididymis from seminiferous tubules
Sperm mature, travel to ductus deferens
Sperm leaving epididymis are immobile
Must undergo capacitation to become motile

13. Ductus Deferens (Vas Deferens)
Ascends into abdominal cavity, descends behind bladder
Peristalsis pushes sperm in ductus deferens
Sperm can be stored for several months
Ductus deferens joins seminal gland to create ejaculatory duct
Duct empties into urethra
Vasectomy cuts ductus deferens

15. The Accessory Glands Generate fluid components of semen
Seminal Glands (Vesicles)
Contribute about 60% of semen volume:
Fructose—energy for sperm
Prostaglandins—stimulate male & female smooth muscle contractions
Slightly alkaline fluid—neutralizes acids in vagina
Contact with secretions causes sperm to start beating flagella

16. Prostate Gland
Surrounds urethra as it leaves the bladder
Produces fluids that add to seminal fluids
Bulbourethral Glands
Secrete mucus to neutralize acids in male urethra, lubricate tip of penis

18. Fluid that contains sperm & secretions of accessory glands
Semen
Fluid that contains sperm & secretions of accessory glands
Ejaculation expels 2 – 5 mL of ejaculate containing:
Sperm cells (sperm count—20 million – 100 million/mL)
Seminal fluid (secretions)
Enzymes (dissolves vaginal secretions)

19. The External Genitalia
Penis introduces semen into vagina & conducts urine through urethra
Processes don’t occur at the same time
Regions of penis:
Root—attaches penis to body wall
Body (shaft)—contains erectile tissue
Glans—surrounds urethral opening
Prepuce (foreskin) surrounds tip of penis
Removed through circumcision

20. Penis contains three columns of erectile tissue
2 columns of corpora cavernosa; 1 column of corpus spongiosum
Increased blood flow to tissues generate erection
Erectile dysfunction (ED) can result from hormonal, vascular, or nerve damage

22. Hormones & Male Reproductive Function
Follicle-stimulating hormone (FSH) & luteinizing hormone (LH)
Promote spermatogenesis & spermiogenesis
Testosterone
Stimulates bone & muscle growth
Enlarges reproductive organs
Establishes & maintains male secondary sex characteristics (hair growth, lower voice)

23. 19-2 Checkpoint List the male reproductive structures.
On a warm day, would the tissues surrounding the scrotum be contracted or relaxed? Why?
What happens when the arteries within the penis dilate?
What effect would low FSH levels have on sperm production?

24. 19-3: Female Reproductive System
Produces sex hormones, gametes, supports & nourishes developing embryo
Ovaries, uterine tubes, uterus, vagina, external genitalia
Female accessory glands release secretions into female reproductive tract

26. The Ovaries Paired ovaries responsible for:
Producing female gametes (ova)
Secreting female hormones (estrogens & progestins)
Each ovary is flattened, almond-shaped
Supported in abdominal cavity by ovarian ligament

28. Oogenesis
Oogenesis begins before birth, accelerates at puberty, ends with menopause
Oogenesis occurs each month between puberty & menopause
Oogonia form before birth
Primary oocytes undergo meiosis during fetal development (contain 23 chromosomes)
Mature into secondary oocyte during puberty & released each month

29. Follicle Development
Ovarian follicles grow oocytes & promote oogenesis
Primordial follicles begin generation of primary oocyte
Develop into primary follicles at puberty
Primary oocyte within follicle enlarges & divides
Primary follicle expands & becomes secondary follicle
Follicle may then enter ovarian cycle to release oocyte

31. The Ovarian Cycle
Ovarian cycle—28 day cycle divided into follicular phase & luteal phase
Phases separated by ovulation
Follicular phase (days 1 – 14)
FSH triggers secondary follicle to form a tertiary follicle
Oocyte within follicle triggered by LH to become secondary oocyte

32. Ovulation (day 14) Luteal phase (days 15 – 28)
Tertiary follicle ruptures & releases secondary oocyte into uterine tubes
In 1 – 2% of ovulations, more than 1 oocyte is released (multiple births)
Luteal phase (days 15 – 28)
Empty follicle collapses & forms corpus luteum
No fertilization: corpus luteum breaks down & new ovarian cycle begins
Fertilization: corpus luteum remains & prevents another ovarian cycle

34. The Uterine Tubes
Uterine tubes (Fallopian tubes/oviducts) connect ovaries to uterus
Infundibulum partially surrounds ovarian edge
Fimbriae (projections) draw ovulated egg into uterine tube
Uterine tube peristalsis draws oocyte into uterine cavity
Fertilization must occur within hours of ovulation

35. The Uterus
Provides protection & nutrition for developing embryo & fetus
Regions of uterus
Body—largest division of uterus
Cervix—bottom of uterus; opening leads into uterine cavity
Uterine wall made of inner endometrium, muscular myometrium & covered by perimetrium

37. The Uterine Cycle
Uterine cycle (menstrual cycle)—repeating changes in endometrium
Menarche—first uterine cycle; menopause—last uterine cycle
Average uterine cycle is 28 days; can be longer or shorter
First phase: menses (days 1 – 7)
Endometrial lining degenerates due to low progesterone & estrogen
Lining shed as menstruation

38. Second phase: proliferative phase (days 7 – 14)
Rising estrogen triggers growth & thickening of endometrial lining
Third phase: secretory phase (days 15 – 28)
Endometrium prepares for developing embryo
Declining hormone levels trigger menses
Last day of uterine cycle occurs with menstruation
Begins first day of next cycle

39. The Vagina Extends from uterus to body’s exterior
Vaginal walls contain blood vessels & smooth muscle
Hymen—tissue that partially blocks vaginal entrance
Functions:
Passageway for menstrual fluids
Receives penis during sexual intercourse
Passes fetus during childbirth

40. The External Genitalia
Vulva—area containing external female genitalia
External genitalia includes:
Labia minora surround vaginal opening
Clitoris composed of erectile tissue
Vestibular glands lubricate vagina
Labia majora conceal vaginal structures

42. The Mammary Glands
Mammary glands nourish infants by producing & secreting milk
Lactation—milk production
Each breast contains mammary gland within subcutaneous fat
Mammary gland opens to surface at the nipple
Areola—area surrounding nipple
Mammary gland composed of lobes that release milk through lactiferous duct

44. Breast Cancer Caused by tumors in the mammary glands
Leading cause of death in women 35 – 45; most common in women older than 50
12% of women develop breast cancer in their lifetime
Risk factors:
Family history of breast cancer
First pregnancy after age 30
Early first period or late menopause

45. Hormones & Female Reproductive Cycle
Circulating hormones coordinate ovarian & uterine cycles
Hormones & the Follicular Phase
FSH stimulates follicular growth; follicles stimulate estrogen release
Estrogen
Stimulates bone & muscle growth
Establishes female secondary sex characteristics (breast development, fat deposit)

46. Hormones & the Luteal Phase
Estrogen levels rise as follicle matures
Day 14: estrogen peaks, LH levels surge & trigger ovulation
Hormones & the Luteal Phase
Corpus luteum releases progesterone to prepare uterus for pregnancy
Stimulates endometrial lining
If no pregnancy, corpus luteum breaks down, progesterone levels fall, endometrial lining is shed

48. 19-3 Checkpoint Name the female reproductive structures.
How would a blockage of the uterine tubes affect a woman’s ability to conceive?
Which layer of the uterus is shed during menstruation?
What changes would you expect to observe in the ovarian cycle if the LH surge did not occur?

49. 19-4: Male & Female Sexual Function
Sexual arousal stimulates nervous system & leads to increased blood flow, causing an erection
Emission—peristalsis pushes semen & fluid into urethra
Ejaculation releases semen through orgasm
Impotence—inability to achieve or maintain erection

50. Female Sexual Function
Arousal stimulates nervous system & leads to increased blood flow to clitoris
Vaginal surfaces increase lubrication
Female orgasm includes peristalsis of uterine & vaginal walls
May cause semen to be drawn into uterus

51. 19-4 Checkpoint
List the physiological events of sexual intercourse in both sexes, and indicate those that occur in males but not in females.

52. 19-5: Functional Changes Due to Age
Menopause
Time after which ovulation & menstruation stop; typically between ages 45 – 55
2 million oocytes present at birth, only a few hundred thousand present at puberty, only a few hundred ovulated
Decreased estrogen levels, “hot flashes,” osteoporosis common

53. Male Climacteric
Male climacteric—declining reproductive function in males (similar to menopause)
Testosterone levels decrease
Sperm production continues throughout most of male’s life

54. 19-5 Checkpoint
Define menopause.
What is the male climacteric?

55. Sexually Transmitted Diseases
Sexually transmitted diseases (STDs)—infections transferred through sexual activity
Most common cause of reproductive disorders
Gonorrhea & syphilis used to be most common STDs; numbers are rising again
Currently herpes, HPV, chlamydia most common STDs

56. Many STDs go unnoticed in early stages, especially in women
Symptoms of STDs:
Burning sensation during urination
Vaginal / penile discharge
Sores, blisters, bumps or rashes
STDs cause pelvic inflammatory disease in females; can damage the uterus
Abstinence is the best way to prevent STDs

57. Birth Control Methods
Contraceptive methods try to avoid fertilization following sexual intercourse
Coitus interruptus
Withdrawal of the penis prior to ejaculation
Least effective means of contraception
Rhythm method
Abstinence before & after ovulation
High rates of pregnancy—ovulation can be hard to calculate

58. Hormonal contraceptives
Mechanical barriers
Prevent sperm cells from entering female; reduce the spread of STDs
Include spermicidal jelly or cream
Ex: condom, diaphragm, cervical cap
Hormonal contraceptives
Manipulate female hormonal cycle to prevent ovulation
Nearly 100% effective if used correctly
Ex: contraceptive pills, Depo-Provera, Norplant, NuvaRing, “morning after” pill

59. Intrauterine device (IUD)
Small plastic device surgically implanted in the uterus
Prevents oocyte implantation for up to 5 years
Sterilization
Male—vasectomy; ductus deferens cut, sperm unable to pass through reproductive tract
Female—tubal ligation; uterine tubes cut, ova unable to pass through reproductive tract
Both are considered permanent