P5 Reproduction in Humans Notes

Reproduction in Humans

Humans reproduce by sexual reproduction, which involves both male and female reproductive cells.

Fertilisation occurs when a male reproductive cell (sperm) fuses with a female reproductive cell (egg).

In humans, fertilisation occurs inside the body of the female. This is known as internal fertilisation.

Sexual reproduction: Involves two parents — a male and a female, each contributing reproductive cells.

Fertilisation: The fusion of the male reproductive cell (sperm) with the female reproductive cell (egg).

Male Reproductive System

The male reproductive system consists of the testes (singular: testis) and the penis.

Men produce millions of sperms at one time to increase the chances of the sperm reaching the egg, for successful fertilisation to occur.

The sperm-carrying fluid leaves the male body through the penis.

Sperm Structure:

A sperm consists of a head, a middle piece and a tail. It is so small that it can only be seen under a microscope.

Head — contains the nucleus, which holds hereditary information
Middle piece — provides energy for movement
Tail — enables the sperm to swim towards the egg

Sperm: The male reproductive cell, consisting of a head (with nucleus containing hereditary information), middle piece, and tail.

Testes: Men produce millions of sperms at one time to increase the chances of the sperm reaching the egg, for successful fertilisation to occur.

Female Reproductive System

The female reproductive system consists of the ovaries (singular: ovary), fallopian tubes, womb, and vagina.

The female reproductive organs are found inside the body.

Functions of Female Reproductive Organs:

Organ	Function
Ovaries	Produce eggs
Fallopian tubes	Carry eggs from ovaries to womb; site of fertilisation
Womb (uterus)	Where the fertilised egg develops
Vagina	Where sperms are deposited during mating; birth canal

The Egg Cell:

The egg is the largest cell in the female human body and contains food for the fertilised egg to grow and develop.

The nucleus of the egg contains hereditary information.

Egg: The female reproductive cell — largest cell in the human body. Contains food reserves and hereditary information in its nucleus.

Ovaries: Produce eggs in a matured female.

Development of a Fertilised Egg into a Baby

Fertilisation Process:

When a male and female mate, many sperms are deposited into the vagina of the female.

The sperms swim towards the egg. Only one sperm will fertilise the egg — the other sperms die.

When the sperm fuses with the egg, fertilisation occurs.

⚠️ Only one sperm can fertilise an egg. The other sperms die in the process.

Fetal Development:

The fertilised egg attaches to the wall of the womb, where it will develop and grow into an embryo.

The fertilised egg undergoes cell division, and the embryo starts to develop organs.

Process	Description
Umbilical cord	The developing baby obtains oxygen and food from the mother's body through the umbilical cord
Waste removal	Waste from the developing baby is passed through the umbilical cord to the mother's large intestine for removal
Mother's abdomen	As the baby develops, the mother's abdomen gets larger
Gestation period	It takes about nine months for the baby to be born after fertilisation

Similarities: Humans and Flowering Plants

Aspect	Humans & Flowering Plants
Type of reproduction	Sexual reproduction
Fertilisation	Sperm fertilises egg; male reproductive cell fertilises female reproductive cell
Inheritance	Reproductive cells contain genetic information from the parents
Traits passed on	Both pass on their traits to their young
Inheritance source	We inherit from both our Father and Mother

Key similarity: Both humans and flowering plants undergo sexual reproduction, where male and female reproductive cells fuse during fertilisation to pass on genetic information and traits to offspring.

Key Takeaways

Humans reproduce by sexual reproduction with internal fertilisation
Sperm (male) has head, middle piece, and tail — swims towards the egg
Egg (female) is the largest cell in the human body; nucleus holds hereditary info
Only one sperm fertilises each egg
The fertilised egg develops in the womb, connected by an umbilical cord
Gestation takes about nine months
Both humans and flowering plants share similar sexual reproduction processes