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Human reproduction

Human reproduction and gestation

Human reproduction and gestation

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Explainer Video

Tutor: Jasmine

Summary

Human reproduction and gestation

In a nutshell

Reproduction is the creation of new life. Humans reproduce by sexual reproduction, during sexual reproduction sperm from a male has fertilised an egg from a female forming an embryo. This embryo develops into a foetus and the foetus grows inside the mother's uterus during gestation. After 40 weeks40\ weeks40 weeks​, a baby is born. 

​


Fertilisation and development

Fertilisation and development occurs in five stages.


1.

Ovulation

An egg is released from an ovary of a female.

2.

Copulation

Sperm from the male is released into the female's vagina during sexual intercourse.

3.

Fertilisation

The nuclei of the egg and sperm fuse , the fertilised egg is called a zygote.

4.

Cell division

24 hours24\ hours24 hours​ after fertilisation, the fertilised egg has divided into two. After four days it has divided into 323232​ cells, it is now an embryo.

5.

Implantation

One week after fertilisation, the embryo implants onto the uterus wall and the placenta begins to form.


​

Gestation

Definition

The time it takes the foetus to develop in the uterus is known as gestation. The foetus relies on its mother for protection against knocks, bumps, and temperature changes, oxygen for respiration, nutrients (food and water) and removal of waste substances such as carbon dioxide. 


Substances such as oxygen and carbon dioxide are exchanged between the mother and foetus through the placenta. The placenta grows on the wall of the uterus and is attached to the foetus via the umbilical cord.




Development of the embryo

The embryo will follow certain developmental milestones. These are listed in the table below. 


Time

Description

​1 month1\ month1 month​​

The embryo is 6 mm6\ mm6 mm​ long. It has a brain, heart, eyes, ears and legs.

​9 weeks9\ weeks9 weeks​​

The body is now 25 mm25\ mm25 mm​ long and completely formed. It is now called a foetus.

​3 months3\ months3 months​​

The foetus is 53 mm 53\ mm53 mm​ long.

​5 months5\ months5 months​​

The foetus is now 160 mm160\ mm160 mm​ long. It kicks and has fingernails.

​7 months7\ months7 months​​

The foetus is now 370 mm370\ mm370 mm​ long and viable. This means it has a fair chance of surviving if it was born now.

​39 weeks39\ weeks39 weeks​​

The foetus is 520 mm 520\ mm520 mm​ long and fully developed. It is ready to be born.

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Learn with Basics

Learn the basics with theory units and practise what you learned with exercise sets!
Length:
Offspring and inheritance

Unit 1

Offspring and inheritance

Animal reproduction

Unit 2

Animal reproduction

Jump Ahead

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Human reproduction and gestation

Unit 3

Human reproduction and gestation

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FAQs - Frequently Asked Questions

What is gestation?

The time it takes the foetus to develop in the uterus is known as gestation.

How do humans reproduce?

Humans reproduce by sexual reproduction, during sexual reproduction sperm from a male has fertilised an egg from a female forming an embryo. This embryo develops into a foetus and the foetus grows inside the mother's uterus during gestation. After 40 weeks​, a baby is born.

What is reproduction?

Reproduction is the creation of new life.

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