Sexual Reproduction


All living things reproduce. Reproduction — the process by which organisms make more organisms like themselves.

The reproductive system is essential to keeping a species alive, unlike other body systems, it's not essential to keeping an individual alive.

male and female reproductive systems

OB31 use illustrative diagrams to identify & locate the main parts of the male and female reproductive systems

Most species have two sexes: male and female. Each sex has its own unique reproductive system. They are different in shape and structure, but both are specifically designed to produce, nourish, and transport each sexes gametes.

Female Reproductive system

What Is the Female Reproductive System?

The human female has a reproductive system located entirely in the pelvis (that's the lowest part of the abdomen). The external part of the female reproductive organs is called the vulva, which means covering.

Located between the legs, the vulva covers the opening to the vagina and other reproductive organs located inside the body.

The fleshy area located just above the top of the vaginal opening is called the mons pubis (pronounced: manz pyoo-bis). Two pairs of skin flaps called the labia (which means lips and is pronounced:lay-bee-uh) surround the vaginal opening. The clitoris(pronounced: klih-tuh-rus), a small sensory organ, is located toward the front of the vulva where the folds of the labia join. Between the labia are openings to the urethra (the canal that carries urine from the bladder to the outside of the body, which is pronounced: yoo-ree-thruh) and vagina. Once girls become sexually mature, the outer labia and the mons pubis are covered by pubic hair.

A female's internal reproductive organs are the vagina, uterus, fallopian tubes, and ovaries.

The vagina is a muscular, hollow tube that extends from the vaginal opening to the uterus. The vagina is about 3 to 5 inches (8 to 12 centimeters) long in a grown woman. Because it has muscular walls it can expand and contract. This ability to become wider or narrower allows the vagina to accommodate something as slim as a tampon and as wide as a baby. The vagina's muscular walls are lined with mucous membranes, which keep it protected and moist. The vagina has several functions: for sexual intercourse, as the pathway that a baby takes out of a woman's body during childbirth, and as the route for the menstrual blood (the period) to leave the body from the uterus.

A thin sheet of tissue with one or more holes in it called the hymen (pronounced: hi-mun) partially covers the opening of the vagina. Hymens are often different from person to person. Most women find their hymens have stretched or torn after their first sexual experience, and the hymen may bleed a little (this usually causes little, if any, pain). Some women who have had sex don't have much of a change in their hymens, though.

The vagina connects with the uterus (pronounced: yoo-tuh-rus), or womb, at the cervix. The cervix has strong, thick walls. The opening of the cervix is very small, which is why a tampon can never get lost inside a girl's body. During childbirth, the cervix can expand (dilate) to allow a baby to pass.

The uterus is shaped like an upside-down pear, with a thick lining and muscular walls — in fact, the uterus contains some of the strongest muscles in the female body. These muscles are able to expand and contract to accommodate a growing fetus and then help push the baby out during labor. When a woman isn't pregnant, the uterus is only about 7.5 cm long and 5 cm wide.

At the upper corners of the uterus, the fallopian tubes connect the uterus to the ovaries. The ovaries are two oval-shaped organs that lie to the upper right and left of the uterus. They produce, store, and release eggs into the fallopian tubes in the process called ovulation. Each ovary measures about 4 to 5 cm in a grown woman.

There are two fallopian tubes, each attached to a side of the uterus. The fallopian tubes are about 4 inches (10 centimeters) long and about as wide as a piece of spaghetti. Within each tube is a tiny passageway no wider than a sewing needle. At the other end of each fallopian tube is a fringed area that looks like a funnel. This fringed area wraps around the ovary but doesn't completely attach to it. When an egg pops out of an ovary, it enters the fallopian tube. Once the egg is in the fallopian tube, tiny hairs in the tube's lining help push it down the narrow passageway toward the uterus.

The ovaries are also part of the endocrine system because they produce female sex hormones such as estrogen and progesterone.

A woman has a fixed number of eggs, her "ovarian reserve", which are released gradually over her fertile life.

The Male Reproductive system

The male genitals include:

the testicles

the duct system, which is made up of the epididymis and the vas deferens

the accessory glands, which include the seminal vesicles and prostate gland

the penis

In a guy who has reached sexual maturity, the two testicles, or testes, produce and store millions of tiny sperm cells. The testicles are oval-shaped and grow to be about 2 inches (5 centimeters) in length and 1 inch (3 centimeters) in diameter. The testicles are also part of the endocrine system because they produce hormones, including testosterone. Testosterone is a major part of puberty in boys, and as a guy makes his way through puberty, his testicles produce more and more of it. Testosterone is the hormone that causes boys to develop deeper voices, bigger muscles, and body and facial hair, and it also stimulates the production of sperm.Alongside the testicles are the epididymis and the vas deferens, which make up the duct system of the male reproductive organs. The vas deferens is a muscular tube that passes upward alongside the testicles and transports the sperm-containing fluid called semen. The epididymis is a set of coiled tubes (one for each testicle) that connects to the vas deferens.

all the above from

OB32 recall that the menstrual cycle lasts about 28 days and that menstruation occurs at the start of the cycle

menstrual cycle

The Menstrual cycle is a regularly occurring sequence of changes that take place in a fertile non-pregnant female’s body by which an egg cell is released from the ovary approximately every 28 days.

The Menstrual cycle is the wombs way of freshly preparing itself for pregnancy. When the female body reaches a level of physical maturity early in puberty it builds up a lining on the womb wall.

This lining will serve to allow the embryo (the baby at the beginning) to attach to the womb wall if fertilization has taken place. Usually fertilization will not have taken place, and so this opportunity to reproduce is gone. The womb releases the lining and the whole cycle start here.

Each cycle a new lining forms on the wall of the uterus to receive and nourish that cycle’s egg cell should it be fertilised. If it is not fertilised then the lining breaks down and is discharged by way of the vagina.

day1 The lining breaks down and passes out from the vagina.

day5 The lining builds up

day13 An egg is released from the ovary

day14 Egg travels down the fallopian tube

day 15 Egg is in place on the womb

Fertilization not achieved so the cycle starts again.


OB33 understand the following in relation to human reproduction:

• fertile period in the menstrual cycle

Time in which Sexual intercourse is Most Likely to lead to Pregnancy.

The most fertile period in the menstrual cycle must be about the same time as ovulation takes place, around day 14, As it takes the egg about 2 days to travel down the fallopian tube , this means that the fertile period can go until day 16.

Some sperm can survive inside the females body for up to 3 days, it is concievable that sexual intercourse up to 3 days prior to ovulation could also lead to fertilization.

From this we can say that day 11 until day 16 has the greatest chance of fertilization taking place.

Do not become complacent with this information, the 28 day cycle is a rough guide to the menstrual cycle, it has been known also for an egg to be released from the other ovary during the cycle.

The most fertile period (the time with the highest likelihood of pregnancy resulting from sexual intercourse) covers the time from some 5 days before until 1–2 days after ovulation.

Weschler (2002), pp.242,374

• sexual intercourse

Is the coming together of a male and female. Both will become aroused, for the man this will lead to a hardening of his penis.

Glossary for reproduction

1. Copulation: the act of sexual intercourse

2. Orgasm: in males results in semen being expelled from the penis (ejaculation).

3. Insemination: sperm are released into the vagina. The egg releases a chemical that the sperm swim towards (chemotaxis)

• fertilisation is the fusion between male and female gametes (sperm and egg) resulting in a zygote;

Fertilisation: The nucleus of the sperm fuses with the nucleus of the egg to form a zygote.

Fertilisation occurs in the fallopian tube.

A gamete is also known as a sex cell, females have a sex cell or gamete called _____

males have a sex cell or gamete called _____

• pregnancy and birth


The gestation period for humans is 38 weeks

Weeks 0 - 9

the Placenta is an organ & gland

The Formation of the Placenta

1. The embryo forms an outer membrane called a chorion.

2. The chorion develops villi which form the placenta along with the blood vessels of the mother in the endometrium (lining of the womb).

3. The umbilical cord connects the embryo with the placenta. It contains blood vessels which take blood from the embryo out to the placenta and back again.

Functions of the Placenta

• Exchange

The placenta allows food and oxygen to diffuse from the mother to the embryo, and waste materials and carbon dioxide to pass in the other direction.

• Barrier

Prevents mother’s blood and baby’s blood mixing.

Important because mother’s blood pressure would be too high for the embryo and if the blood groups are different they would clump.

Amniotic sac and fluid.

Amniotic fluid is the fluid that surrounds your baby in your uterus (womb). It’s very important for your baby’s development.

The amniotic sac (bag) inside the uterus holds your growing baby. It is filled with amniotic fluid. This sac forms about 12 days after getting pregnant

How does amniotic fluid keep your baby healthy?

During pregnancy, your uterus is filled with amniotic fluid. Here’s what the fluid does:

  • Cushions and protects your baby
  • Keeps a steady temperature around your baby
  • Helps your baby’s lungs grow and develop because your baby breathes in the fluid
  • Helps your baby’s digestive system develop because your baby swallows the fluid
  • Helps your baby’s muscles and bones develop because your baby can move around in the fluid
  • Keeps the umbilical cord (the cord that carries food and oxygen from the placenta to your baby) from being squeezed

Stages of birth

Stage 1: dilation

- contractions of the uterus push the head of the foetus towards the cervix.

- The amnion bursts

- The Cervix (usually pin sized) dilates (widens) up to 10cm and amniotic fluid is released.

Stage 2: delivery

- head of the baby is forced out through the vagina by contractions

Stage 3: placental

- the afterbirth (placenta and foetal membranes) are expelled from the vagina.

• growth and puberty

growth and puberty

a zygote undergoes cell division and develops within the womb into a foetus

The baby is born, continues to grow and divide cells, until the end of puberty, when the offspring is now capable of having their own children.

the company cow & gate on what growing babies need ....

OB34 understand that there are many forms of contraception, and that some of these prevent fertilisation


(the use of) any of various methods intended to prevent a woman becoming pregnant

There are many methods that prevent copulation leading to fertilization.

  1. Barrier Methods
  2. Hormonal Methods
  3. Intrauterine
  4. Sterilization
  5. Behavioural methods

Barrier methods

Prevent the sperm from coming in contact with the egg. In effect it acts as a barrier that the sperm cannot get through.

Condoms prevent STI's (sexually transmitted infections)

condom, femidom's/Pages/Howefficientarecondoms.aspx

Hormonal Methods

Oestrogen and Progesterone are used in the contracepticve pill as they prevent the relaease of eggs

This is truly worth a look, check out the male and female forms of contraception,

DO THE QUIZ ... and check your answers

Play the dodge game

Check it out, ta si ann!

Follow this link to the states web site on Contraception,

The following are a list of common misconceptions that are NOT true, and should NEVER be believed.

The responsibility of a human life being completely dependent on YOU is a serious matter.


Modern misconceptions and urban legends have given rise to a great many false claims:

  • The suggestion that douching with any substance immediately following intercourse works as a contraceptive is untrue. While it may seem like a sensible idea to try to wash the ejaculate out of the vagina, it is not likely to be effective. Due to the nature of the fluids and the structure of the female reproductive tract, douching most likely actually spreads semen further towards the uterus. Some slight spermicidal effect may occur if the douche solution is particularly acidic, but overall it is not scientifically observed to be a reliably effective method. Douching is neither a contraceptive nor a preventative measure against STDs or other infections.
  • It is untrue that a female cannot become pregnant as a result of the first time she engages in sexual intercourse.
  • While women are usually less fertile for the first few days of menstruation,[43] it is a myth that a woman absolutely cannot get pregnant if she has sex during her period.
  • Having sex in a hot tub does not prevent pregnancy, but may contribute to vaginal infections.[44]
  • Although some sex positions may encourage pregnancy, no sexual positions prevent pregnancy. Having sex while standing up or with a woman on top will not keep the sperm from entering the uterus. The force of ejaculation, the contractions of the uterus caused by prostaglandins[citation needed] in the semen, as well as ability of sperm to swim overrides gravity.
  • Urinating after sex does not prevent pregnancy and is not a form of birth control, although it is often advised anyway to help prevent urinary tract infections.[45]
  • Toothpaste cannot be used as an effective contraceptive[46].


Think before you Act,

your whole life will change if you or your partner become pregnant,

consider all alternatives and options.

Extra knowledge

Same Placenta in the identical twins.


Seahorses typically mate for life. The male seahorse is equipped with a brood pouch on the ventral, or front-facing, side. When mating, the female seahorse deposits the eggs in the male's pouch, which the male then internally fertilizes. The male carries the eggs until they emerge, expelling fully-developed, miniature seahorses in the water.


When two parties discover a mutual interest at the beginning of breeding season, they court for several days, even while others try to interfere. During this time they have been known to change color, swim side by side holding tails or grip the same strand of sea grass with their tails and wheel around in unison in what is known as their “pre-dawn dance”. They eventually engage in their “true courtship dance” lasting about 8 hours, during which the male pumps water through the egg pouch on his trunk which expands and cleaves open to display an appealing emptiness. When the female’s eggs reach maturity, she and her mate let go of any anchors and snout-to-snout, drift upward out of the seagrass, often spiraling as they rise. The female inserts her ovipositor into the male’s brood pouch, where she deposits her eggs, which the male fertilizes. The fertilized eggs then embed in the pouch wall and become enveloped with tissue.[5] New research indicates the male releases sperm into the surrounding sea water during fertilization, and not directly into the pouch as was previously thought.[6] Most seahorse species' pregnancies last two to four weeks.

As the female squirts anywhere from dozens to thousands of eggs from a chamber in her trunk into the male pouch, her body slims while his swells. Both seahorses then sink back to the bottom and she swims away. Scientists believe the courtship behaviour serves to synchronize the movements of the two animals so that the male can receive the eggs when the female is ready to deposit them. The eggs are then fertilized in the father’s pouch which is coursed with prolactin, the same hormone responsible for milk production in pregnant women. He doesn’t supply milk, but his pouch provides oxygen as well as a controlled environment incubator. The eggs then hatch in the pouch where the salinity of the water is regulated; this prepares the newborns for life in the sea.[7][8] Throughout the male’s incubation, his mate visits him daily for “morning greetings”. The female seahorse swims over for about 6 minutes of interaction reminiscent of courtship. They change color, wheel around sea grass fronds, and finally promenade, holding each other’s tails. Then, the female swims away until the next morning, and the male goes back to vacuuming up food through his snout.

On the other hand Komodo Dragons are able to reproduce without Parthenogenesis, birth without fertilization


The production of milk by the mother.

Stimulated by the hormone prolactin.


A liquid high in proteins, minerals and anitbodies that is produced for the first few days after birth in breast milk.

Test yourself here