The Reproductive System

The reproductive system takes care of a truly vital process, the creation of life.

Cells

• The male and female each have their own specialized reproductive cell. In the male it is the sperm cell (spermatozoon) and in the female it is the egg cell (ovum). When these two cells meet in a process known as fertilization, a new life is created.

Sperm cells

• Approximately 300 million sperm cells are made daily in the testes .

• The sperm take 4 weeks to mature.• They can live for one month in the testes.• If they are not ejaculated, they are absorbed by the

body.• Sperm cells are one of the smallest cells in the body.• Each sperm cell contains half the genetic code

necessary for life.

Ova

• Egg cells (ova) are produced in the ovaries.

• A million egg cells are already produced by the time a girl is born.

• By age 10, only 50 to 100 thousand are left.

• At puberty, 20 egg cells start to develop each month. One egg cell dominates and is released.

Ova

• If multiple eggs are released, it could result in multiple births.

• A woman releases on average 400 to 500 egg cells in a lifetime.

• Each egg cell contains half the genetic code.

Organs in the Male Reproductive System

The sperm cells are produced and stored in the testes, the male sex gland. They travel through a series of tubes, epididymus and sperm ducts, where they mix with a nourishing fluid called semen that is made in the seminal and prostate glands. Sperm exit the body through the urethra, a tube in the penis, in a process called ejaculation.

Organs in the Female Reproductive System

Approximately 14 days after the first day of her period, an egg cell is released from an ovary, the female sex gland. The egg travels along the fallopian tubes to the uterus, also known as the womb. If the egg is fertilized it will embed itself in the uterine wall. If not, it will be shed along with the lining of the uterus in the next period, exiting the body through the cervix and the vagina.

Connections to Other Systems

The reproductive system is dependent on other body systems.

• The digestive-excretory system: this system is such a close neighbor that the two systems are sometimes referred to as the urogenital system. In males, organs such as the urethra are shared by both systems. The urethra, used to ejaculate sperm, also carries urine from the bladder.

Connections to Other Systems• The endocrine system: hormone glands such as

the pituitary gland, located in the brain (part of the nervous system)create chemicals to stimulate the reproductive organs.

o FSH follicle stimulating hormone-

encourages egg/sperm production

o LH luteining hormone- stimulates

ripening and release of egg/production

of testosterone

o Estrogen- the main female hormone-

increases egg ripening, prepares uterine

lining, and causes general female body

features (breasts, broad hips. . .)

Connections to Other Systemso Testosterone- made in the testes, stimulates the production of

sperm and causes male body features (broad shoulders, facial hair . . .)

o hCG human chorionic gonadotropin hormone- produced by the fertilized egg when it implants on the wall of the uterus, is detectable in urine by pregnancy tests within 10 days of fertilization.

• The circulatory system: hormones circulate around the body in the blood, but only target certain organs to stimulate them into action. Sexual organs, notably the penis, become engorged in blood during

sexual activity. The uterine wall is rich in blood tissue.

Connections to Other Systems

The muscular-skeletal system:

• In the male system specialized muscles in the scrotum provide climate control for the testes, whose temperature must be slightly lower than body temperature for sperm production. The scrotum muscles move the testes close to the body for warmth and protection and

away from the body for a cooler

environment.

Smooth muscles lining the vas deferens contract to ejaculate sperm.

Connections to Other Systems

• The female system houses some of the strongest muscles in the human body: uterine muscles contract to expel the fetus and the cervical muscle, a circular muscle at the opening to the womb, opens from 0.5 cm to 10 cm during childbirth. Vaginal walls are lined with muscles that can expand and contract.

The nervous system: many nerve endings are found in the reproductive organs, making them extremely sensitive. Some sexual response is controlled by the automatic nervous system.

The integumentary system: the external sex organs are covered in skin.

Reproductive Health

• As with other systems diet and exercise are important for reproductive health.

• Since men and women’s reproductive organs are different, they have specific health concerns.– As men’s reproductive organs are external, they require

protection during sports or rough activity. Injury may effect sperm production.

– Women require no such protection but must visit a doctor every year for a pap smear .

Reproductive Problems

• Timing – Egg ripe 1-2 days after ovulation– Sperm live 3-4 days– Therefore sex must occur within a day or to of

ovulation.

• Sperm count– Less than 20-30 million per ejaculation– Causes: illness, injury, stress, fatigue, drugs(including

alcohol) and some prescription drugs– Treatment: hormones, drugs, surgery

Reproductive Problems

• Erectile difficulty• Malformed sperm – poor swimmers• Female reproductive tract issues

– Irregular ovulation (ineffective hormone control)

– Fallopian tube is blocked

– Uterine lining is not rich enough

– Chemical balance of vagina and uterus is hostile to sperm

Common Problems

• Heavy/irregular periods

• Breast lumps (harmless cyst, infection or tumor)

• Ovarian cysts (usually harmless)

• Endometriosis (uterine tissue lodging elsewhere causing pain)

Common Problems

• STI’s

• Cancer of testes (excellent cure rate with early detection)

• Undescended testes • Enlarged prostateBalantis (swelling and

redness of end of penis)

Reproductive Technologies

• IVF In vitro fertilization

• AI artificial insemination

• Contraception– Calendar– Pills

• Daily

• Patch

• Morning after

• Barrier– Condoms– Dental dam– Diaphragm

• Chemicals– Spermicide

• IUD intrauterine device– Prevents implantation of egg– Upsets chemical balance

Careers

• Genetic counselor• Endocrinologist• Gynecologist• Family doctor• Public Health Nurse• Oncologist

                                    

Bibliography

Parker, Steve. Reproduction. Chicago:Raintree, 2004.Parker, Steve. The Reproductive System. Texas:

Raintree, 1998.“Structure and Function of the Male Reproductive

System.” Health Information Home. Last Reviewed: 11/16/2001. Cleveland Clinic Health System. http://www.cchs.net/health/healthinfo/docs/2300/2376.asp?index=9117

 

Photo Credits

• worms.zoology.wisc.edu/ urchins/SUfert_intro.html

• encyclopedia.thefreedictionary.com/ fertilization 

• www.ericolson.addr.com/ artwk7.html

• www.absolutelypaper.com/ store/birth.asp 

• www.besthealth.com/.../ html/repr_sys_fin.html 

• www.justeves.com/.../ images/male_genitals.gif

• www.cancerhelp.org.uk/ help/default.asp?page=3074

• getreligion.typepad.com/ getreligion/politics/• http://www.babyhopes.com/articles/hcg.html 

• http://www.cchs.net/health/health-info/docs/2300/2376.asp?index=9117