BIOLOGY OF HUMAN AGING CHAPTER 14 The Reproductive System

Reproductive System of Humans Reproductive Functions of Female: u Produces eggs (ova) u Receives sperm u Incubates and nourishes the embryo and fetus u Gives birth All of these processes are regulated and coordinated by hormones secreted by: u Hypothalamus u Pituitary gland u Ovaries

Reproductive System of Humans Major Organs of Female Reproductive System: n Ovaries: Produce ova and sex hormones. u Follicles: A single egg with surrounding cells that nourish and protect it.

Frontal View of Female Reproductive System

Side View of Female Reproductive System

Female Reproductive System: u Ovulation & Oogenesis: After puberty, each month one immature egg (oocyte), is released from ovary. F Pituitary hormone FSH (follicle stimulating hormone) causes a follicle to enlarge. F Another pituitary hormone LH (luteinizing hormone) causes the secondary oocyte to be released by the ovary during ovulation.

Oogenesis and Ovary Structure

Major Organs of Female Reproductive System: n Oviducts (Fallopian Tubes): Transport the egg from the ovary to the uterus. u Fertilization

Fertilization Occurs in the Oviducts

Reproductive System of Humans Major Organs of Female Reproductive System: n Uterus: Incubates the embryo/fetus. u Endometrium: Inner mucous lining, which thickens each month in preparation for pregnancy. u If fertilization does not occur, endometrium breaks down and is discharged during menstruation. u If fertilization occurs, the egg implants in the endometrium which supports its growth until the placenta develops.

Reproductive System of Humans Major Organs of Female Reproductive System: n Cervix: Lower portion of the uterus, which projects into the vagina. n Vagina: Thin walled, muscular chamber. u Receives the sperm and penis u Acid pH kills bacteria and sperm cells n External structures: u Clitoris: Equivalent to male penis. u Labia minora: Skin folds that border vaginal opening. u Labia majora: Protect entire genital region.

Stages of Female Reproductive Cycle

Reproductive System of Humans Reproductive Functions of Male: u Produces sperm u Delivers sperm to female reproductive tract All of these processes are regulated and coordinated by hormones secreted by: u Hypothalamus u Pituitary gland u Testes (Sing. Testis)

Side View of Male Reproductive System

Front View of Male Reproductive System

Major Organs of Male Reproductive System: n Testes: Paired male gonads. u Produce sperm through spermatogenesis, which produces four sperm cells of equal size. u Spermatogenesis occurs in a vast system of hollow tubes called seminiferous tubules. u Sperm

Spermatogenesis Occurs in Seminiferous Tubules of Testes

Reproductive System of Humans Major Organs of Male Reproductive System: n Epididymus: u Large coiled tube that surrounds testes. u Stores sperm while they develop fertilizing ability and motility (about 20 days). n Vas Deferens: u Long muscular ducts from scrotum to back of bladder. u During ejaculation, the sperm pass from epididymus into these two ducts.

Reproductive System of Humans Major Organs of Male Reproductive System: n Ejaculatory Duct: u Short duct after two vas deferens ducts unite. n Urethra: u Deliver sperm to the exterior. u In males, urine and sperm pass through the urethra.

Reproductive System of Humans Major Organs of Male Reproductive System: Accessory Glands: n Seminal vesicles (2): Secrete fluid that nourishes sperm. u Thick, clear, alkaline fluid. u Contains: F Fructose: Provides energy for sperm motility. u Sperm cells become highly motile when mixed with this fluid.

Accessory Glands: Produce semen. n Prostate gland: Produces a thin milky secretion. u Largest of semen secreting glands. F Produces an antibiotic that may prevent urinary tract infections in men.

Major Organs of Male Reproductive System: Accesory Glands: Produce semen. n Bulbourethral glands (2): Release a mucous secretion that lubricates penis and facilitates its entry into vagina.

Major Organs of Male Reproductive System: n Penis: organ that delivers sperm to female body. u Composed of three cylinders of erectile tissue. u During sexual arousal, the penis fills with blood from the arteries. u Erection is essential for penetration. u Impotence is the inability to maintain an erection. F May be caused by alcohol, drugs, illness, and/or emotional problems. F Viagra acts by relaxing smooth muscle of penis blood vessels, allowing blood to enter erectile tissue.

Age-related changes n Changes in Men u Decrease in size and firmness of testes with aging u Decline in the secretion of testosterone u Decline in number of sperm cells u Degeneration of some seminiferous tubules u Fibrous connective tissue formation increases between the tubules  diminish blood supply  atrophy u Semen volume reduced with aging u Prostate gland often enlarge with aging u Seminal vesicles decrease in weight and storage capacity u A decrease in secretory activities of Bulbourethral glands u Atrophy of penis  loss of elasticity  problem in erection

Age-related changes n Changes in Women u Reduced amounts of estrogens and progesterone being secreted u Cessation of the menstrual cycle  signal beginning of menopause u Changes in follicle cells in the ovaries  unable to respond to FSH and LH u Symptoms associated with onset of menopause: F Hot flashes, sweating, and red patches as a result of irregular dilation and constriction of blood vessels. u Atrophy of ovaries and increase formation of fibrosis. u Degeneration of follicles (follicular cysts) u Reproductive organs tend to decrease in size u Uterine tubes become thin and undergo weaker peristaltic contraction. Also more infections. u The vagina becomes narrower and shorter. u Loss of elasticity and dryness of vagina due to less secretion of glands associated with female reproductive organs. Hormonal and other observable changes

Age-related Dysfunctions n Cancer n Atrophic Vaginitis n Prolapse of the Uterus n Impotence n Diminish Sexual Functioning