The Human Gas Exchange System and Breathing — Revision Notes | KS3 Biology

Brain dump

Before you look at anything else, write down everything you can remember about this lesson: key words, facts, examples. Spelling doesn't matter. Then see which of the 17 key terms you remembered.

2:00

Everything you remember

Key terms

Gas exchange system: A group of organs that work together so you can breathe, also called the respiratory system
Trachea: The windpipe, a tube held open by rings of cartilage that air travels down
Bronchi: The two tubes the trachea splits into, one going into each lung
Bronchus: One of the two bronchi on its own
Bronchioles: Smaller and smaller branching tubes inside the lungs, like the twigs on a tree
Alveoli: Tiny air sacs at the ends of the bronchioles
Circulatory system: The organ system the heart belongs to, with the heart pumping blood
Diaphragm: A dome-shaped sheet of muscle that sits underneath the lungs
Intercostal muscles: Muscles in between the ribs that are attached to the ribcage and move it
Ribcage: The protective cage the ribs form around the lungs
Contract: When a muscle gets shorter and pulls
Relax: When a muscle lets go
Pressure: All the tiny pushes from gas molecules hitting the walls of a container, added up
Volume: The amount of space inside something, such as the chest or a box
Inhalation: Breathing in
Exhalation: Breathing out
Bell jar model: A chest model: a jar for the ribcage, balloons for the lungs and a rubber sheet for the diaphragm

What this lesson covers

How well do you know each one? Be honest: red means go back over it.

Name the parts of the gas exchange system in the order air passes through them
Explain why the heart is not part of the gas exchange system
Identify the diaphragm and intercostal muscles and describe where they are
Explain how changing the volume of a gas changes its pressure
Describe the steps of breathing in and breathing out
Evaluate how well the bell jar model represents a real chest

Test yourself

Cover the answer, say it out loud, then check the full quiz on the lesson page.

Which of these is NOT part of the gas exchange system?
As your chest gets bigger, what happens to the pressure in your lungs?
What actually makes air move into your lungs?

Topic quiz

21 questions on this topic only — not mixed with anything else, one at a time.

Question 1 of 21

Spelling challenge

Read the definition, then type the correct spelling of the term. Uses the same terms as above.