Functions of the Reproductive SystemFunctions of the Reproductive System

The male reproductive system performs the following functions:

1.Production of sperm cells.2.Sustaining and transfer of the sperm cells

to the female.3. Production of male sex hormones.

The female reproductive system performs the following functions:

1.Production of female sex cells.2.Reception of sperm cells from the male.3.Nurturing the development of and providing

nourishment for the new individual.4.Production of female sex hormones.

Reproductive System Overview

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

Male Reproductive SystemTestes

Duct system•Epididymis•Ductus deferens•Urethra

Accessory organs•Seminal vesicle•Prostate gland•Bulbourethral gland

External genitalia•Penis•Scrotum

MALE REPRODUCTIVE SYSTEM OVERVIEW ANIMATIONDOUBLE CLICK TO PLAY

TESTES

•The two testes (sing. testis) are suspended outside the abdominal cavity in a Sacramento called scrotum. The scrotum is made of actin and smooth muscles known as the dartos muscle.

•In the embryo, the testes lie in the abdominal cavity near the kidneys about two months before birth: the testes descend through the inguinal canal into the scortum. The descent is due to the effect or the hormone of testosterone.

•The seminiferous tubules are lined by stratified epitheliumcomposed of two types of cells: supporting cells and the spermatogenic cells. Sertoli cells provide mechanical support and protection to the developing germ cells.

• Coverings of the testes

Tunica albuginea – capsule that surrounds each testis

Septa – extensions of the capsule that extend into the testis and divide it into lobules

• 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

DUCT SYSTEM

EPIDIDYMIS•Comma-shaped, tightly coiled tube•Found on the superior part of the testis and along the posterior lateral side•Functions to mature and store sperm cells (at least

20 days)•Expels sperm with the contraction of muscles in

the epididymis walls to the vas deferens

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

- Ends in the ejaculatory duct which unites with the urethra

Vasectomy – cutting of the ductus deferens at the level of the testes to prevent transportation of sperm

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

Regions of the urethraProstatic urethra –surrounded by prostateMembranous urethra – from prostatic urethra to penisSpongy (penile) urethra – runs the length of the penis

ACCESSORY ORGANSSEMINAL VESICLE

•Located at the base of the bladder•Produces a thick, yellowish secretion (60% of semen)•Fructose (sugar)•Vitamin C•Prostaglandins•Other substances that nourish and activate sperm

PROSTATE GLAND•Surrounds the proximal part of the male urethra as it

emerges from the urinary bladder•Secretion of prostate gland is thin, opalescent liquid with

a slightly acid reaction. Itcontains proteolytic enzymes and fibrinolysin.

•Secretes a milky fluid•Helps to activate sperm•Enters the urethra through several small ducts

BULBO-URETHRAL GLANDS•Largest among the male reproductive accessory glands.•Pea-sized gland inferior to the prostate•Produces a thick, clear mucus•Cleanses the urethra of acidic urine•Serves as a lubricant during sexual intercourse•Secreted into the penile urethra

Semen•Mixture of sperm and accessory gland secretions•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

EXTERNAL GENITALIA

PENIS•External genital organ through which the urethra passes.

This is known as the main organ of copulation. •The two corpora cavernosa lie in the posterior surface while the corpus spongiosum is on the anterior surface.•The distal end of the penis expands into the glands penis. A fold of the skin covers the gland called prepuce which is removed during circumcision.•Internally there are three areas of spongy erectile tissue around the urethra

SCROTUM

• Divided sac of skin outside the abdomen• Maintains testes at 3°C lower than normal body temperature to protect sperm viability

ORGANTestis Seminiferous tubules Interstitial cellsEpididymis

Vas deferensSeminal vesicle

Prostate gland

Bulbourethral glandScrotumPenis

FUNCTION

Produce sperm cellsProduce and secrete male sex hormonesStores sperm cells undergoing maturation, conveys

sperm cells to vas deferensConveys sperm cells to ejaculatory ductSecretes an alkaline fluid containing nutrients and

prostaglandins that helps neutralize the acidic components of semen

Secretes an alkaline fluid that helps neutralize semen’s acidity and enhances sperm cell motijity

Secretes fluid that lubricates end of penisEncloses, protects, and regulates temperature of testesConveys semen into vagina during sexual intercourse;

glans penis is richly supplied with sensory nerve endings associated with feelings of pleasure during sexual stimulation

Summary of the functions of Male Reproductive Organs

Spermatogenesis

•Production of sperm cells•Begins at puberty and continues throughout life•Occurs in the seminiferous tubules

Processes of Spermatogenesis•Spermatogonia (stem cells) undergo rapid mitosis to

produce more stem cells before puberty•Follicle stimulating hormone (FSH) modifies spermatogonia

divisionOne cell produced is a stem cellThe other cell produced becomes a primary spermatocyte

•Primary spermatocytes undergo meiosis•Haploid spermatids are produced•Spermiogenesis

Late spermatids are produced with distinct regionsHead – contains DNA covered by the acrosomeMidpieceTail

Sperm cells result after maturing of spermatids•Spermatogenesis takes 64 to 72 days

Processes of Spermatogenesis

Anatomy of a Mature Sperm Cell

• The only human flagellated cell

• DNA is found in the head

Testosterone Production

• The most important hormone of the testes• Produced in interstitial cellsFunctions of testosterone

– Stimulates reproductive organ development– Underlies sex drive– Causes secondary sex characteristics

• Deepening of voice• Increased hair growth • Enlargement of skeletal muscles• Thickening of bones

Regulation of Male Androgens (Sex Hormones)

FEMALE REPRODUCTIVE SYSTEM

Ovaries

Duct System– Uterine tubes (fallopian tubes)– Uterus– Vagina

External genitalia

FEMALE REPRODUCTIVE SYSTEM OVERVIEW ANIMATIONDOUBLE CLICK TO

PLAY

OVARIES•Germinal and endocrine glands of the female.•Small organs suspended in the pelvic cavity by ligamentsSuspensory ligaments – secure ovary to lateral walls of

the pelvis Ovarian ligaments – attach to uterusBroad ligament – a fold of the peritoneum, encloses

suspensory ligament•Upper ends are intimately attached with the fimbriated ends

of the fallopian tubes.•Outer layer is made up of single layer epithelium. Beaneath

this layer the ova are produced. •This ova begin maturation process, which takes place in small

fluid clusters of cell called ovarian follicles(sac-like structure)• Structure of an ovarian follicle

– Oocyte– Follicular cells

Ovarian Follicle Stages

Primary follicle – contains an immature oocyte

Graafian (vesicular) follicle – growing follicle with a maturing oocyte

Ovulation – when the egg is mature the follicle ruptures

– Occurs about every 28 days

The ruptured follicle is transformed into a corpus luteum

FALLOPIAN TUBES (OVIDUCTS/UTERINE TUBES)

• Each tube is about 10 centimeters long and passes medially to the uterus, penetrates its wall, and opens into the uterine cavity

• Receive the ovulated oocyte

• Provide a site for fertilization

• Does not physically attach to the ovary

• Supported by the broad ligament

Uterine Tube Function

• Fimbriae – finger-like projections at the distal end that receive the oocyte

• Cilia inside the uterine tube slowly move the oocyte towards the uterus (takes 3–4 days)

• Fertilization occurs inside the uterine tube

UTERUS• Located between the urinary bladder and rectum• Hollow muscular organ shaped like an inverted

pear• Size change greatly during pregnancy

nonpregnant, adult state – 7 cm long, 5 cm wide and 2.5 cm in diameter

• The upper two-thirds, or body of the uterus has a dome shaped top

• Functions of the uterus– Receives a fertilized egg– Retains the fertilized egg– Nourishes the fertilized egg

Support for the Uterus

Broad ligament – attached to the pelvis

Round ligament – anchored interiorly

Uterosacral ligaments – anchored posteriorly

Regions of the Uterus

Body – main portion

Fundus – area where uterine tube enters

Cervix – narrow outlet that protrudes into the vagina

Walls of the UterusEndometrium

– Inner layer– Covered with columnar epithelium and contains

abundant tubular gland – Allows for implantation of a fertilized egg– Sloughs off if no pregnancy occurs (menses)

Myometrium – thick, middle, muscular layer consists largely

bundles of smooth muscle fibersPerimetrium

– outer serosal layer that covers the body of the uterus and part of the cervix

During pregnancy, the uterus expands to 500 times its normal size

VAGINA

• Fibromuscular tube, about 9 cm long

• Extends from cervix to exterior of body

• Behind bladder and in front of rectum

• Serves as the birth canal

• Receives the penis during sexual intercourse

• Hymen – partially closes the vagina until it is ruptured

• The vaginal walls has three layers

Inner mucosal layer – stratified squamous epithelium, lacks mucous glands.

Middle muscular layer – consistsmainly of smooth muscle fibers. A voluntary muscle (bulbospongiosus) is primarily responsible for closing this orifice.

Outer fibrous layer – consists of dense connective tissue interlaced with elastic fibers. It attaches the vagina to surrounding organs.

External Genitalia (Vulva)

MONS PUBIS• Fatty area overlying the pubic symphysis• Covered with pubic hair after puberty

LABIA MAJORA• Folds of skin from mons pubis to pudendal cleft

containing subcutaneous adipose tissueand smooth muscle. The skin of the outer surface is pigmented and set with hair

• Sebaceous and swest glands are numerous in the outer and inner surface.

LABIA MINORA• Two small folds between the labia majora

surrounding the vaginal orifice.

CLITORIS• Corresponds embryologically to the dorsal part of

the penis It consist s of erectile tissues.• Located about 1 inch anterior to the urethral

opening. • Serves as guiding parting locating the urethra when

performing catheterization..VESTIBULE• Dorsal to the clitoris and between the two folds of

the labia minora.• Has several openings: urethral and vaginal, found

behind the urethra and ducts of the vestibular glands.

• The hymen is a membrane of variable size,partly blocking the vaginal opening in the virgin.

ORGANOvary

Uterine tube

Uterus

Vagina

Labia majora

Labia minora

Clitoris

Vestibule

Vestibular glands

FUNCTIONProduces oocytes and female sex hormones

Conveys secondary oocyte toward uterus; site of fertilization; conveys developing embryo to uterus

Protects and sustains embryo during pregnancy

Conveys uterine secretions to outside of body; receives erect penis during sexual intercourse; provides open channel for offspring during birth process

Enclose and protect other external reproductive organs

Form margins of vestibule; protect openings of vagina and urethra

Produces feelings of pleasure during sexual stimulation due to abundant sensory nerve endings in glans

Space between labia minora that contains vaginal and urethral openings

Secrete fluid that moistens and lubricates vestibule

Summary of the functions of Female Reproductive Organs

OOGENESISProcess of egg cell formation

Oogonia – female stem cells found in a developing fetus

Oogonia undergo mitosis to produce primary oocytes

Primary oocytes are surrounded by cells that form primary follicles in the ovary

Oogonia no longer exist by the time of birth

• Primary oocytes are inactive until puberty• Follicle stimulating hormone (FSH) causes

some primary follicles to mature– Meiosis starts inside maturing follicle

• Produces a secondary oocyte and the first polar body

– Meiosis is completed after ovulation only if sperm penetrates

• Two additional polar bodies are produced

Menstrual (Uterine) Cycle

• Cyclic changes of the endometrium• Regulated by cyclic production of estrogens and

progesterone• Stages of the menstrual cycle

– Menses – functional layer of the endometrium is sloughed

– Proliferative stage – regeneration of functional layer

– Secretory stage – endometrium increases in size and readies for implantation

Hormonal Control of the Ovarian and Uterine Cycle

MAJOR EVENTS IN A REPRODUCTIVE CYCLE

1. Anterior pituitary gland secretes follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

2. FSH stimulates maturation of a follicle.

3. Follicular cell cells produce and secrete estrogens.

4. Anterior pituitary releases a surge of LH, which stimulates ovulation.

5. Follicular cells become corpus luteum cells which secrete estrogen and progesterone.

6. If the egg cell is not fertilized, the corpus luteum degenerates and no longer secretes estrogen and progesterone.

7. As concentration of estrogen and progesterone decline, blood vessels in the uterine lining constrict.

8. Uterine lining disintigrates and slough off, producing menstrual flow.

9. Anterior pituitary no longer inhibited and again secretes FSH and LH.

10.The reproductive cycle repeats.

Hormone Production by the Ovaries

Estrogens– Produced by follicle cells– Cause secondary sex characteristics

• Enlargement of accessory organs• Development of breasts• Appearance of pubic hair• Increase in fat beneath the skin• Widening and lightening of the pelvis• Onset of menses

Progesterone– Produced by the corpus luteum– Production continues until LH diminishes in

the blood– Helps maintain pregnancy

Menopause

termination of reproductive cycles due to aging of the ovaries .

reduced concentration of estrogens and lack of progesterone may cause regressive changes in female secondary sex characteristics.

MAMMARY GLANDS

• Accessory organs of the female reproductive system that are specialized to secrete milk following pregnancy

• Present in both sexes, but only function in females– Modified sweat glands

• Composed of lobes that contain glands and duct• Dense connective and adipose tissues separate

the lobes• Ovarian hormones stimulate female breast

development - Alveolar glands and ducts enlarge - Fat is deposited around and within the breasts

Anatomy of the Breast

• Areola – central pigmented area

• Nipple – protruding central area of areola

• Lobes – internal structures that radiate around nipple

• Alveolar glands – clusters of milk producing glands within lobules

• Lactiferous ducts – connect alveolar glands to nipple

Clinical Terms Related to the Reproductive Systems

• amenorrhea – abscence of menstrual flow, usually due to a disturbance in hormonal concentrations.

• conization – surgical removal of a cone of tissue from the cervix for examination.

• curettage – surgical procedure in which the cervix is dilated and the endometrium of the uterus is scraped.

• dysmenorrhea – painful menstruation.• endometriosis – tissue similar to the inner lining of the

uterus occuring within the pelvic cavity.• endometritis – inflammation of the uterine lining.• epididymitis – inflammation of the epididymis.• hematometra – accumulation of menstrual blood within

the uterine cavity.

• hysterectomy – surgical removal of the uterus.• mastitis – inflammation of the mammary gland.• oophorectomy – surgical removal of an ovary.• oophoritis – inflammation of an ovary.• orchiectomy – surgical removal of a testis.• orchitis – inflammation of a testis.• prostatectomy – surgical removal of a portion of the

prostate gland.• prostatitis – inflammation of the prostate gland.• salpingectomy – surgical removal of a uterine tube.• vaginitis – inflammation of the vaginal lining.• varicocele – distension of the veins within the spermatic

cord.