Biology 3 - Exchange of Materials - Exchange in the Lungs

Your body needs a constant supply of oxygen for cellular respiration. Breathing brings this in, and removes all the waste C02.

Your lungs are found in the upper part of your body (The Thorax), protected by the ribcage. They are seperated by the digestive organs in the lower part of body (Abdomen) by the Diaphragm.

The job of the breathing system is to bring air in and out of your lungs. It brings in air rich with Oxygen, and removes waste C02

When you breathe in, your ribs move up and out, and your Diaphragm flattens from its normal Domed Shape. This pulls air into your lungs.

When you breathe out, the opposite happens. Your ribs move down and in, while your Diaphragm returns to its Domed Shape. This expels the air in your lungs out of your body.

The lungs are specially adapted to make Gas Exchange more effective. Within them, are tiny little air sacs, called Alveoli. These Alveoli:

- Have a very large surface area (More area to diffuse)

- Are Moist

- A large bloody supply (To maintain a concentration gradient)

- Thin walls (Makes diffusion quicker)