The human body. The skin. Life processes. Life stages.

1. UNIT 1.
YOUR BODY
Natural Science 3

2. The human body
Parts of the body:
● Head: includes the face, forehead, cheeks and chin.
● Trunk: has two parts (thorax and abdomen).
● Limbs: upper limbs (arms) and lower limbs (legs).
Inside your body
There are different organs:
● Bones and muscles: support and move your body.
● Brain: controls all the organs.
● Heart, lungs, stomach, kidneys and intestines → Trunk

3. The skin
The skin is an elastic organ.
You can feel:
● Heat.
● Cold.
● Pain.
The skin on your head has got a lot of hair.
Melanin is a substance that protects your
body from sunlight.

4. Life processes
Nutrition
1. We take food.
2. We absorb nutrients.
3. They give us energy.
4. We expels waste.
Reproduction
- Reproduction is the process to have offspring similar to ourselves.
Sensitivity
- Senses (sight, hearing, taste, smell and touch) detect and respond to
changes.

5. You grow and change: Life stages
Infancy (0-3 years)
Childhood (3-12 years)
- It’s the first stage of life.
- Babies drink mother’s milk.
- Milk teeth appear.
Adolescence (12-18 years)
- Boys and girls go through different changes.
- Boys grow facial and body hair.
- Girls develop breast and their bodies changes.
Adulthood (18-70 years)
- The body is fully-developed.
- Some men lose their hair.
- Adults work and look after their children
Old Age (70 ⇒ years)