glossary

a tough, white tissue that forms part of the skeleton of humans and other animals. Cartilage is not as stiff as bone. Cartilage is found in the ear, nose, and joints.
 * cartilage:**

a gas without color or smell that is made up of carbon and oxygen. Carbon dioxide is in the air and is used in soft drinks. Frozen carbon dioxide is called dry ice.
 * carbon dioxide:**

Are a sort of veins but they are stronger and sort of elastic. They carry the blood away from the body. Thye start moving away from the heart and they start to get much smaller. The arteries that are most thick can be as thick as a thumb, the thinist can be thinner than hair. They are called arterioles and they carry the red blood. This colour comes from the oxygen it carries around.
 * arteries: **

They are the hairs up your nose that help take all the germ out of the oxygen before it goes into the body so you have less probability of getting ill.
 * celia:**

It is drop of something in this case a small drop of saliva that come out when you cough.
 * droplets: **

They are small air sacks that are in your lungs.
 * alveoli:**