Definitions

Reproduction is the production of new organisms. There are two types of reproduction : sexual and asexual.

Male Reproductive System

The male reproductive system consists of several organs. It has the following functions :

1) Produce, store and transport sperm (male gamete)
2) Discharge sperm to female reproductive system
3) Produce and secrete testosterone (male sex hormone)

The structures of the male reproductive system can be seen below. Of the many structures, take note of the 7 main reproductive structures.

Features

The scrotum allows the testes to stay below body temperature for better sperm development.

Semen is a thick white fluid mixed with sperm that provides nutrients and lubricates sperm to facilitate their movement.

This table summarizes the other key features of the male reproductive system.

Female Reproductive System

The female reproductive system consists of several organs. It has the following functions :

1) Produce mature eggs (female gamete)
2) Produce progesterone and oestrogen (female sex hormones)

The structures of the female reproductive system can be seen below. Of the many structures, take note of the 5 main reproductive structures.

Features

This table summarizes the key features of the female reproductive system.

The Gametes

The reproductive cells are known as gametes. The gametes of the human body are the sperm and the egg. Normal human cells contain 23 pairs of chromosomes. However, each sperm and egg contains only 23 chromosomes.

Introduction

Puberty describes the body changing from a child to an adult, with sex organs becoming fully functional and producing mature gametes.

Boys vs Girls

Boys and girls undergo very different forms of puberty, and at different ages as well. The key differences are highlighted in the table.

Introduction

During fertilization, the nuclei of the sperm and egg fuse, passing on certain hereditary characteristics of the parents to the offspring.

The Process

Fertilization occurs in 4 general stages:

1) A mature egg is released from the ovary into the fallopian tube (ovulation).

2) Sperm discharged during sexual intercourse swim towards the fallopian tube to meet the egg. One sperm penetrates and fertilizes the egg to form a zygote.The zygote contains 23 pairs of chromosomes.

3) The zygote moves towards the uterus with the help of tiny hairs on the fallopian tube walls. It starts to divide into a ball of cells (embryo).

4) The embryo reaches the uterus after 7 days and implants into the uterine wall. Blood vessels in the uterine lining provide essential nutrients for embryo development into a foetus.

After Fertilization

The placenta and umbilical cord develop. The placenta connects the foetus to the uterine wall via the umbilical cord, a tube.

Importance of Placenta

The placenta delivers nutrients and oxygen to the foetus and removes waste substances from it. The placenta also prevents the mixing of blood.

Introduction

The menstrual cycle takes place in the female reproductive system every month, with average length of 28 days. It is regulated by progesterone and oestrogen, and involves shedding of the uterine lining.

Key Events

The menstrual cycle involves two main events : menstruation and ovulation.

Menstruation is the shedding of the uterine lining whereas ovulation is the release of a mature egg from one of the ovaries.

The Process

The process of the menstrual cycle was shown in the cycle above. This table now summarises the different events in the cycle.

Influencing factors

The timing and duration of the stages of the menstrual cycle are affected by many things. Here are just some of the factors:

1) Emotional disturbances
2) Stress
3) Mental fatigue
4) Illness
5) Unbalanced diet / malnutrition