1. Respiratory System
Year 8 Science – Chapter 3.2

2. The respiratory system
Respiration is a cellular process that is a series of chemical changes that releases energy in your cells.
The system of organs and tissues that takes the air into the body and makes the oxygen available for your cells is the respiratory system.

3. The epiglottis stops food entering the trachea
Flap of skin that covers the top of the trachea when you are swallowing
To the respiratory system
To the digestive system

4. How breathing works

5. Breathing
When you breathe in, some air may come in through your mouth but most of it comes in through your nose
Large dust particles are filtered out as the air passes through the hairs inside your nostrils.
Glands in the skin lining the nose produce sticky mucus. The mucus helps tiny hairs called cilia lining the nose to trap fine particles

6. When you breath in …
Your diaphragm flattens and your lungs expand when you breath in.
The opposite happens when you breath out.

7. Parts of the respiratory system
The warm, moist air then passes down the trachea (windpipe). The trachea divides into two bronchi, which divide into ever smaller tubes (bronchioles), eventually ending in a cluster of sacs called alveoli. This is where gas exchange takes place in the lungs.

8. The lungs and gas exchange
The lungs contain thin layers of tissue which separates blood from air
The lungs are moist and have a large surface area
Oxygen dissolves in the moist surface of the alveoli and moves by a process called diffusion from a short distance from the space inside an alveolus to the blood

9. Respiration
Respiration begins once the oxygen and glucose are together in the cells. The two chemicals react together. Carbon dioxide and water are produced in the reaction, and energy is released. It is this energy your body uses for all its activities.

10. What do the lungs do

11. eBook Drag and Drop Activities

12. Into Science Activity