BIOLOGY OF HUMAN AGING

CHAPTER 14CHAPTER 14

The Reproductive SystemThe Reproductive System

Reproductive System of HumansReproductive System of Humans

Reproductive Functions of Male:Reproductive Functions of Male: Produces spermProduces sperm Delivers sperm to female reproductive tractDelivers sperm to female reproductive tract

All of these processes are regulated and coordinated All of these processes are regulated and coordinated by hormones secreted by:by hormones secreted by: HypothalamusHypothalamus Pituitary glandPituitary gland Testes (Sing. Testis)Testes (Sing. Testis)

Side View of Male Reproductive System

Front View of Male Reproductive System

Major Organs of Male Reproductive System:Major Organs of Male Reproductive System: Testes: Testes: Paired male gonads.Paired male gonads.

Produce sperm through Produce sperm through spermatogenesisspermatogenesis, , which produces four sperm cells of equal size.which produces four sperm cells of equal size.

Spermatogenesis occurs in a vast system of Spermatogenesis occurs in a vast system of hollow tubes called hollow tubes called seminiferous tubules.seminiferous tubules.

SpermSperm

Spermatogenesis Occurs in Seminiferous Tubules of Testes

Reproductive System of HumansReproductive System of Humans

Major Organs of Male Reproductive System:Major Organs of Male Reproductive System: Epididymus:Epididymus:

Large coiled tube that surrounds testes.Large coiled tube that surrounds testes. Stores sperm while they develop fertilizing Stores sperm while they develop fertilizing

ability and motility (about 20 days).ability and motility (about 20 days). Vas Deferens:Vas Deferens:

Long muscular ducts from scrotum to back of Long muscular ducts from scrotum to back of bladder.bladder.

During ejaculation, the sperm pass from During ejaculation, the sperm pass from epididymus into these two ducts.epididymus into these two ducts.

Reproductive System of HumansReproductive System of Humans

Major Organs of Male Reproductive System:Major Organs of Male Reproductive System: Ejaculatory Duct:Ejaculatory Duct:

Short duct after two vas deferens ducts unite.Short duct after two vas deferens ducts unite.

Urethra:Urethra: Deliver sperm to the exterior.Deliver sperm to the exterior. In males, urine and sperm pass through the urethra.In males, urine and sperm pass through the urethra.

Reproductive System of HumansReproductive System of Humans

Major Organs of Male Reproductive System:Major Organs of Male Reproductive System:

Accessory GlandsAccessory Glands:: Seminal vesicles (2):Seminal vesicles (2): Secrete fluid that Secrete fluid that

nourishes sperm.nourishes sperm. Thick, clear, alkaline fluid.Thick, clear, alkaline fluid. Contains:Contains:

FructoseFructose: Provides energy for sperm motility.: Provides energy for sperm motility.

Sperm cells become highly motile when mixed Sperm cells become highly motile when mixed with this fluid.with this fluid.

Accessory Glands: Produce semen.Accessory Glands: Produce semen. Prostate gland:Prostate gland: Produces a thin milky Produces a thin milky

secretion.secretion. LargestLargest of semen secreting glands. of semen secreting glands.

Produces an antibiotic that may prevent urinary Produces an antibiotic that may prevent urinary tract infections in men.tract infections in men.

Major Organs of Male Reproductive System:Major Organs of Male Reproductive System:

Accesory Glands: Produce semen.Accesory Glands: Produce semen. Bulbourethral glands (2):Bulbourethral glands (2): Release a mucous secretion Release a mucous secretion

that lubricates penis and facilitates its entry into that lubricates penis and facilitates its entry into vagina.vagina.

Major Organs of Male Reproductive System:Major Organs of Male Reproductive System: Penis:Penis: organ that delivers sperm to female organ that delivers sperm to female

body.body. Composed of three cylinders of Composed of three cylinders of erectileerectile tissue. tissue. During sexual arousal, the penis fills with During sexual arousal, the penis fills with

blood from the arteries.blood from the arteries. Erection is essential for penetration.Erection is essential for penetration. ImpotenceImpotence is the inability to maintain an is the inability to maintain an

erection.erection. May be caused by alcohol, drugs, illness, and/or May be caused by alcohol, drugs, illness, and/or

emotional problems.emotional problems. ViagraViagra acts by relaxing smooth muscle of penis acts by relaxing smooth muscle of penis

blood vessels, allowing blood to enter erectile tissue.blood vessels, allowing blood to enter erectile tissue.

Reproductive Functions of Female:Reproductive Functions of Female: Produces eggs (ova)Produces eggs (ova) Receives spermReceives sperm Incubates and nourishes the embryo and fetusIncubates and nourishes the embryo and fetus Gives birthGives birth

All of these processes are regulated and coordinated All of these processes are regulated and coordinated by hormones secreted by:by hormones secreted by: HypothalamusHypothalamus Pituitary glandPituitary gland OvariesOvaries

Reproductive System of HumansReproductive System of Humans

Major Organs of Female Reproductive Major Organs of Female Reproductive System:System:

Ovaries: Ovaries: Produce ova and sex hormones.Produce ova and sex hormones. FolliclesFollicles: A single egg with surrounding : A single egg with surrounding

cells that nourish and protect it.cells that nourish and protect it.

Frontal View of Female Reproductive System

Side View of Female Reproductive System

Female Reproductive System:Female Reproductive System: Ovulation & OogenesisOvulation & Oogenesis: After puberty, each month : After puberty, each month

one immature egg (one immature egg (oocyteoocyte), is released from ovary. ), is released from ovary. Pituitary hormone Pituitary hormone FSHFSH ( (follicle stimulating follicle stimulating

hormonehormone) causes a follicle to enlarge.) causes a follicle to enlarge. Another pituitary hormone Another pituitary hormone LH LH ((luteinizing luteinizing

hormonehormone) causes the ) causes the secondary oocytesecondary oocyte to be to be released by the ovary during ovulationreleased by the ovary during ovulation ..

Oogenesis and Ovary Structure

Major Organs of Female Reproductive Major Organs of Female Reproductive System:System:

Oviducts (Fallopian Tubes):Oviducts (Fallopian Tubes): Transport the Transport the egg from the ovary to the uterus.egg from the ovary to the uterus. FertilizationFertilization

Fertilization Occurs in the Oviducts

Reproductive System of HumansReproductive System of Humans

Major Organs of Female Reproductive System:Major Organs of Female Reproductive System: Uterus: Uterus: Incubates the embryo/fetus.Incubates the embryo/fetus.

EndometriumEndometrium: Inner mucous lining, which : Inner mucous lining, which thickens each month in preparation for thickens each month in preparation for pregnancy.pregnancy.

If fertilization does not occur, endometrium If fertilization does not occur, endometrium breaks down and is discharged during breaks down and is discharged during menstruationmenstruation..

If fertilization occurs, the egg implants in the If fertilization occurs, the egg implants in the endometrium which supports its growth until the endometrium which supports its growth until the placentaplacenta develops. develops.

Reproductive System of HumansReproductive System of Humans

Major Organs of Female Reproductive System:Major Organs of Female Reproductive System: Cervix: Cervix: Lower portion of the uterus, which Lower portion of the uterus, which

projects into the vagina.projects into the vagina. Vagina: Vagina: Thin walled, muscular chamber.Thin walled, muscular chamber.

Receives the sperm and penisReceives the sperm and penis Acid pH kills bacteria and sperm cellsAcid pH kills bacteria and sperm cells

External structures:External structures: ClitorisClitoris: Equivalent to male penis.: Equivalent to male penis. Labia minoraLabia minora: Skin folds that border vaginal opening.: Skin folds that border vaginal opening. Labia majoraLabia majora: Protect entire genital region.: Protect entire genital region.

Stages of Female Reproductive Cycle

Age-related changes

Changes in MenChanges in Men Decrease in size and firmness of testes with agingDecrease in size and firmness of testes with aging Decline in the secretion of testosteroneDecline in the secretion of testosterone Decline in number of sperm cellsDecline in number of sperm cells Degeneration of some seminiferous tubulesDegeneration of some seminiferous tubules Fibrous connective tissue formation increases between the tubulesFibrous connective tissue formation increases between the tubules

diminish blood supply diminish blood supply atrophy atrophy Semen volume reduced with agingSemen volume reduced with aging Prostate gland often enlarge with aging Prostate gland often enlarge with aging Seminal vesicles decrease in weight and storage capacitySeminal vesicles decrease in weight and storage capacity A decrease in secretory activities of Bulbourethral glandsA decrease in secretory activities of Bulbourethral glands Atrophy of penis Atrophy of penis loss of elasticity loss of elasticity problem in erection problem in erection

Age-related changes

Changes in WomenChanges in Women Reduced amounts of estrogens and progesterone being secreted Reduced amounts of estrogens and progesterone being secreted Cessation of the menstrual cycleCessation of the menstrual cycle signal beginning of menopause signal beginning of menopause Changes in follicle cells in the ovariesChanges in follicle cells in the ovaries unable to respond to FSH unable to respond to FSH

and LHand LH Symptoms associated with onset of menopause:Symptoms associated with onset of menopause:

Hot flashes, sweating, and red patches as a result of irregular dilation Hot flashes, sweating, and red patches as a result of irregular dilation and constriction of blood vessels. and constriction of blood vessels.

Atrophy of ovaries and increase formation of fibrosis.Atrophy of ovaries and increase formation of fibrosis. Degeneration of follicles (follicular cysts)Degeneration of follicles (follicular cysts) Reproductive organs tend to decrease in sizeReproductive organs tend to decrease in size Uterine tubes become thin and undergo weaker peristaltic Uterine tubes become thin and undergo weaker peristaltic

contraction. Also more infections.contraction. Also more infections. The vagina becomes narrower and shorter. The vagina becomes narrower and shorter. Loss of elasticity and dryness of vagina due to less secretion of Loss of elasticity and dryness of vagina due to less secretion of

glands associated with female reproductive organs.glands associated with female reproductive organs.Hormonal and other observable changes Hormonal and other observable changes

Age-related Dysfunctions

CancerCancer Atrophic VaginitisAtrophic Vaginitis Prolapse of the UterusProlapse of the Uterus ImpotenceImpotence Diminish Sexual FunctioningDiminish Sexual Functioning