Your lungs are two spongy organs inside your chest. They are a key part of your respiratory system, which is all about breathing. Every time you breathe in, your lungs fill with air. When you breathe out, they push air back out. This process happens about 12 to 20 times every minute without you even thinking about it. The main job of your lungs is to bring oxygen into your body and remove a waste gas called carbon dioxide. Oxygen is needed by every cell in your body to make energy.

Without it, your cells would not be able to work properly. When you inhale, air travels through your nose or mouth, down your windpipe (also called the trachea), and into two tubes called bronchi. Each bronchus leads into one lung. Inside the lung, the bronchus branches into many smaller tubes called bronchioles, like the branches of a tree. At the ends of these tiny tubes are millions of little air sacs called alveoli. They look like bunches of grapes. The alveoli have very thin walls and are surrounded by tiny blood vessels called capillaries.

This is where the important gas exchange happens. Oxygen from the air inside the alveoli passes through the thin walls into the blood in the capillaries. At the same time, carbon dioxide, which is a waste gas from your body's cells, moves from the blood into the alveoli. This exchange happens very quickly. The blood then carries the oxygen to all parts of your body. When you breathe out, the carbon dioxide is pushed out of your lungs and leaves your body. This amazing process is called gas exchange. It keeps your body supplied with the oxygen it needs and gets rid of waste gases.

When you inhale, air travels through your nose or mouth, down your windpipe (also called the trachea), and into two tubes called bronchi.

Breathing is not just something your lungs do on their own. A large, dome-shaped muscle called the diaphragm helps. It sits below your lungs. When you inhale, your diaphragm contracts and flattens out, pulling downward. At the same time, the muscles between your ribs (called intercostal muscles) contract and pull your rib cage up and out. This makes your chest bigger and creates a vacuum. Air rushes in to fill your lungs. When you exhale, your diaphragm relaxes and moves up, your rib muscles relax, and air is pushed out.

Your lungs are amazing organs that work hard every second. They are protected by your rib cage. To keep your lungs healthy, it is important to exercise regularly, avoid smoking or breathing in smoke, and stay away from polluted air. Deep breathing exercises can also strengthen your lungs. When you run, your lungs work faster to supply more oxygen to your muscles. That is why you breathe harder during exercise. Understanding how your lungs work helps you appreciate just how important they are for life.