The human respiratory system
In this topic you will:
- learn the names of the different parts of the human respiratory system
- observe carefully, and record your observations, as the structure of lungs is demonstrated.
Key words
- aerobic respiration
- air sac
- bronchiole
- bronchus
- cartilage
- larynx
- respiration
- respiratory system
- trachea
- vocal cords
- voicebox
- windpipe
Why we need oxygen
You may remember that one of the characteristics shared by all living things is respiration. Respiration is a series of chemical reactions that happens inside every living cell.
The kind of respiration that usually happens inside our cells is called aerobic respiration. Aerobic respiration uses oxygen. The cells produce carbon dioxide as a waste product.
The air around you contains oxygen. When you breathe, you take air into your lungs. Some of the oxygen from the air goes into your blood. The blood delivers the oxygen to every cell in your body, so that the cells can use it for respiration. The blood collects the waste carbon dioxide from the cells, and takes it back to your lungs.
The organs that help you to take oxygen out of the air, and get rid of carbon dioxide, make up the respiratory system.
Quick fact: Why do cells need oxygen?
Oxygen is essential for aerobic respiration. It helps cells release energy from food. Without oxygen, cells wouldn’t get enough energy to carry out basic life processes.
Common mistake
Some people think we breathe in oxygen just to fill our lungs. In fact, oxygen is needed by every cell in your body to release energy from food through respiration.
The structure of the human respiratory system
This is a diagram of the human respiratory system. The white spaces in this diagram are the ‘tubes’ (bronchi and bronchioles) that air moves through, as it goes into and out of your lungs.
The human respiratory system
Air gets into your body through your mouth or nose. Your mouth and nose both connect to your trachea. The trachea is sometimes called the windpipe. It has strong rings of cartilage around it. These rings of cartilage keep the trachea open and prevent it collapsing, so that air can be kept moving in and out of your body. If you put your fingers on the front of your neck and move them downwards, you can feel the rings of cartilage on your trachea.
The trachea branches into two bronchi (singular: bronchus). The bronchi also have cartilage to support them. One bronchus goes to each lung. Each bronchus carries air deep into the lungs. Each bronchus divides into several smaller tubes called bronchioles. The structure of these branches allows the air to reach deeper into the lungs.
The bronchioles end by branching into many tiny structures called air sacs. This is where the oxygen goes into the blood, and the carbon dioxide comes out. You can find out more about this in the next topic.
Note
The trachea does not collapse because it is reinforced by strong rings of cartilage. You can feel these rings by gently pressing on the front of your neck.
Questions
Show Answer
Nose or mouth → trachea → bronchi → bronchioles → alveoli
Show Answer
Alveoli → bronchioles → bronchi → trachea → nose or mouth