4.1 Understanding Sexual and Asexual Reproduction

Process that take place in living organisms in order to perpetuate their respective species

Process of producing now individuals from living organisms

Process of generating offspring

Biologically process that occurs in all living organisms

Importance of reproduction

The way to increase the number of individual or offspring of the same species.

Importance for the survival of all living organisms

Importance to maintaining continuity of organisms without a mechanisms for reproduction, life would come to end

Fertilization

Fertilization is a fusion process between a male gamete and a female gamete to produce a zygote.

The are two types of fertilization :

a) internal fertilization

b) external fertilization

The internal fertilization takes place in the body of the female animal. The male animal puts the male reproductive cell into the female reproductive system for fertilization to take place.

The external fertilization takes place outside the body of the female animal. Ovum and sperm are produced respectively by the female and male animal at the same time into water for the fertilization to take place.

The internal fertilization take place in mammals, reptiles, birds and insects.

The external fertilization takes place in fish, frogs and toads.

Disadvantage of external fertilization:

a) a lot of reproductive cells need to be produced

b) a lot of reproductive cells diet before fertilization occurs

c) a lot of ovum and sperms are wasted, as they are washed away by water

d) the zygote or embryo produced may be eaten by other animals

Reproduction are divide by two :

- Sexual reproduction

- Asexual reproduction

Sexual Reproduction

Production of new individuals by the living organisms

Sex cells called gametes

Process of producing a new individuals through the fusion of one male reproductive cell (female gamete) to produce zygote. Zygote will develop to form a new individual.

Organisms that carry out sexual reproduction include

a) human

b) all vertebrate animals

c) insects

d) most flowering plants

Asexual reproduction

Production of new individuals by living organisms without involving sex cells

Involves one individual organisms

Does not involve the fusion of male and female sex cells.

No gamete involves

A simple cell is divided by itself to produce an exact duplicate of an organisms.

There are 5 types of asexual reproduction: binary fusion, budding, spore formation, vegetative reproduction and rejuvenation

Organisms that produce asexual are :

a) paramecium

b) hydra

c) amoeba

d) flowering and non-flowering

4.2 Male Reproduction System

The male reproductive system functions to produce male gametes which are called sperms.

The main male reproductive organs include :

a) Testis

b) Penis

c) Scrotum

d) Urethra

e) Sperm duct

f) Prostate gland

Figure 1: Male reproductive organs

Part	Description and function
Sex glands	- These include the seminal vesicle and prostate gland. Sex glands secrete fluid which contains nutrients for the sperm.
Sperm duct	- A tube which transports sperms from the testis to the urethra inside the body.
Scrotum	- A sac which hangs outside the body - It holds and protects the testes
Urethra	- A tube that runs through the penis - It is a passage that allows sperm to flow out of the body - It is a passage that allows urine from the bladder to be excreted to the outside of the body.
Penis	- Male sex organ which is made up of soft tissues and rich with blood vessels - It transfers semen into the vagina of the female during copulation
Testis	- Produces the male gametes (sperm) and male sex hormones

Table 1 : Functions of the male reproductive organs

SPERM

Figure 2 : Structure of the sperm

The sperm is the smallest cell in the male body. It can move or swim on its own by moving its tail in the fluid.

Each sperm has three sections; head, neck and tail.

The sperm nucleus contains heredity substances that can be passed on to the next generation.

Changes in males during puberty

Puberty is the early stage of maturity in a person from a physical and spiritual perspective.

At the puberty, the male will experience physical, physiological (body functions) and emotional changes.

A male reaches puberty when he is about 12 to 14 years of age.

At puberty, a male will experience the following changes:

a) growth of moustache and beard

b) enlargement of bones and muscles

c) growth of pubic and armpit hair

d) voice becomes hoarse

e) testis begins to produce sperm

f) begins to release semen

g) begins to show interest in female

4.3 Female reproductive system

The female reproductive system functions to produce female gametes called ovum.

The main female reproductive organs include :

a) ovary

b) uterus

c) Fallopian tube

d) Vagina

e) Cervix

The oviduct is a narrow vessel that joins the ovary with the uterus. The Fallopian tube is the first part of the oviduct. Fertilization occurs here.

Figure 3 : Female reproductive organs

Reproductive	Function
Ovary	- Produces ovum
Fallopian tube	- Channels ovum from the ovary to the uterus - A place where fertilization occurs
Uterus	-Accommodates and protects the embryo
Cervix	-Connects the uterus with the vagina -Produces mucus for sperm movement
Vagina	-Receives sperms from the penis -Produces mucus for sperm movement

Table 2 : Functions of the female reproductive.

Ovum

The ovum is the largest cell in the female body. It cannot move by itself.

The ovum contains nucleus, cytoplasm and a thick cell membrane.

The nucleus of an ovum contains heredity substance like in the sperm nucleus.

The ovum cytoplasm provides food for the development of the zygote.

Figure 4 : Structure of ovum

Changes in the female during puberty

At puberty, the female will experience physical, physiological (body functions) and emotional changes just like the male.

Puberty for the female happens when she is about 9 to 12 years of age.

At the puberty, the female will experience the following changes:

a) enlargement of breast and buttocks

b) accumulation of fats under the skin

c) growth of pubic and armpit hair

d) begins to produce ovum

e) begins to menstruate

f) begins to show interest in male

4.4 Menstrual Cycle

Menstruation is the bleeding or blood discharge through the cervix and vagina of the female.

The menstrual discharge contains blood, dead ovum and a layer of tissue which covered the surface of the uterus wall.

During the menstrual cycle, an ovum develops and is released. The uterus is prepared for fertilization. If the ovum is not fertilized, the ovum, together with the uterus wall tissues and blood is eliminated from the body as menstrual discharge.

About every 28 days, an ovum will be released by one ovary and will enter the Fallopian tube. The process of releasing ovum from the ovary is called ovulation.

If an ovum is fertilized by a sperm, a zygote will form and develop into an embryo which will implant itself to the uterus wall. The woman is then said to be pregnant and her menstrual cycle will stop until the baby is born.

If the ovum is not fertilized, it will die after 24-36 hours. The tissue layer on the thick and soft uterus wall will break off and be expelled together with blood through the vagina are menstrual discharge.

The fertile phase is the period when ovulation is most likely to happen.

Human menstrual cycle

Figure 5 : The menstrual cycle

Figure 6 : Menstrual cycle and the fertile phase

Phase 1 : Menstruation phase – 1st to 5th day

Phase 2 : Repair phase – 6th to 11th day

Phase 3 : Fertile phase or ovulation phase – 12th to 16th day

Phase 4 : Premenstrual phase – 17th to 28th day

The fertile phase is between the 11th and 17th day, in that day, the fertilization can occur. This period is called the fertile phase.

An ovum in a female body can live for 24 to 36 hours only. Because the ovum will be released in the middle of the menstrual cycle; about the 14th day, this means that fertilization can occur between the 11th and 17th day to produce a zygote if the sperm enters the Fallopian tube.

A female must take care of her personal hygiene during the menstrual period and carry out daily activities as usual.

When menstruation begins, a female should :

a) wear a clean sanitary pad

b) change the sanitary pad frequently

c) bath as usual to maintain body cleanliness

d) wrap used sanitary pads with a paper or plastic bag before throwing it into a closed rubbish

bin.

Fertilization and Pregnancy

Fertilization is a process whereby the sperm fuses with the ovum to form the zygote.

During copulation, millions of sperms are transferred into the vagina.

From the vagina, the sperms swim through the cervix into the uterus and up the oviduct to meet the ovum.

If the ovum is present in the oviduct, fertilization takes place.

During ovulation, a mature ovum is released.

The ovum moves along the fallopian tube or oviduct towards the uterus.

Millions of sperms are released during the copulation. However, only about 100 will reach the ovum but only 1 is able to fuse with the ovum.

The fusion between the sperm and the ovum is called fertilization.

Fertilization produces a zygote.

The zygote divides in 2, then 4, and so on.

After six days, a ball of cells, now called an embryo, is formed.

When implantation is successful, the woman is said to be pregnant.

It takes 9 month from the time the zygote is formed until the fetus is ready to be born.

Figure 7 : Fertilization of an ovum by a sperm

Development of the embryo into a fetus until birth.

The embryo, which subsequently becomes the foetus, grows inside the uterus in a sac surrounded by a membrane called amnion.

A flexible tube called umbilical cord connects the embryo to the placenta.

Uterus Wall	- Place where embryo implants itself and develops. - Has muscular walls.
Placenta	- Made up of tissue from both mother and the fetus. - Place where exchange of nutrients, oxygen, carbon dioxide and waste materials takes place between the blood of the mother and the fetus
Umbilical Cord	- Tube which connects the fetus to the placenta. - Inside the tube are blood vessels to transport blood to and from the fetus.
Amnion	- Membrane which forms a sac and contains fluid.
Fetus	- Forms from an embryo.
Amniotic Fluid	- Acts as a cushion and absorb shock.

HUMAN LIFECYCLE

			2.Embryo

		4. Fetus with all the parts fully formed

After about 9 months, the fetus is fully formed and ready to be born

The fetus rotates its body until the head points towards the cervix which dilates, and makes the mother goes into labors.

During labor, the muscular wall of the uterus contracts, the amnion bursts and amniotic fluid is released.

The fetus is pushed out through the vagina, the baby is born and the umbilical cord is cut.

THE IMPORTANCE OF PRE-NATAL CARE

Throughout the pregnancy, the fetus obtains food supply and nutrients from the mother’s body through the placenta.

Food intake from the placenta by the fetus through the umbilical cord (tali pusat) is called diffusion.

- Pregnant mothers are encouraged to eat food rich in nutrients.
- These are the nutrients required by a pregnant mother and their functions:

NUTRIENTS	FUNCTIONS
Protein	Assist in the building of new tissues in the body of the fetus.
Calcium and Phosphorus	Important in the building of strong and healthy teeth and bones.
Iron	Building of red blood cells in the blood of the fetus.
Folic acid	Strengthens the defense system of the pregnant mother and her fetus.

THE IMPORTANCE OF RESEARCH IN HUMAN REPRODUCTION

1) Human beings face two main reproduction

problems :

a) Sterility or Infertility (mandul), that is, both husband and wife are unable to reproduce.

b) Birth control, that is, the need to control the number of children in a family.

2) Factors of infertility :

a) for male:

- No sperm in semen.

- Low sperm count.

- Low quality of sperm.

- Impotence (problems with erection of penis).

- Hormone imbalance.

- Infections and diseases.

b) for females:

- Blocked or abnormally functioning Fallopian tubes.

- Ovaries that do not produce eggs.

- Abnormal uterus.

- Hormone imbalance.

- Infections and diseases.

TECHNIQUES TO PREVENT STERILITY

1) Surgery:

a) Laparoscope is the technique of using a laparoscope (an illuminated tubular instrument) to examine the structures inside the abdomen.

2) Artificial insemination:

- this technique is used if the husband is sterile.

- sperm from a donor male are taken and injected into the uterus of the wife during her fertile period to induce pregnancy.

- this method increases the chances of fertilization between the sperm and ovum.

3) Hormone and drug treatment:

- Clomiphene is the hormone used by the wife who find it difficult to ovulate.

- This hormone can stimulate the female to produce ovum.

- Drugs such as Viagra are used to treat impotence in men.

4) Assisted reproductive technologies

(ART):

(a) In Vitro Fertilization (IVF) - Blocked or abnormal Fallopian tube.

(b) Gamete Intra-fallopian Transfer (GIFT) - At least one Fallopian tube is normal. No male fertilization problem.

(c) Zygote Intra-fallopian Transfer (ZIFT) - Man has an infertility problem.

(d) Intra-uterine Insemination (IUI) - Unexplained infertility or certain sperm problems.

BIRTH CONTROL TECHNIQUES

1) Chemical methods :

(a) Contraceptive pills – contain the sex hormone of women which prevent ovulation by changing the states in the ovary.

BIRTH CONTROL PILLS

(b) Spermicidal – are introduced into the wife’s vagina to kill the sperms.

2) Physical methods :

(a) Intra-uterine Device (IUD) – inserted into the uterus can prevent fertilized ovum from implanting in the uterus and also to prevent sperm entering the uterus.

(b) Condom – is a rubber sheath pulled over the penis to prevent sperm from entering the uterus during the ejaculation (pancutan mani).

(c) Diaphragm – is a rubber cap fitted into the cervix of the women to prevent the sperm from entering the Fallopian tube.

Sterility (Permanent Methods)

1) Ligation (Tubectomy) - A process of cutting and tying up both of the Fallopian tubes of the women so that ovum produced cannot be fertilized by any sperm.

2) Vasectomy - A process of cutting and tying both sperm ducts of the male so that sperm cannot flow to the penis.