Lung
From the Simple English Wikipedia, the free encyclopedia that anyone can change
The lung is an organ in many vertebrates (animals having a spine, or backbone). It gives blood oxygen from the air, and takes away carbon dioxide. Most vertebrates have 2 lungs.
In animals, the lungs are the area where respiration takes place. Without respiration in the lungs, animals would not survive as the body cells would not be able to receive the oxygen needed.
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[change] Breathing
[change] Breathing In
To breathe in, the diaphragm, a large sheet of muscle just under the lungs, contracts and moves down. Our ribs, with the help of muscles, move up and outwards.
These all make the space inside our chest much larger and since it has a larger area that what it had before, pressure decreases because there is less air inside and air has to be pushed in to make the pressure inside our chests the same as outside.
[change] Breathing Out
To breathe out, our diaphragm relaxes and moves upwards. Our ribs, with the help of muscles, move in and down.
These all make the space inside our chest much smaller, and too much air is held inside. So most air is pushed out.
[change] Anatomy
[change] Mammalian Lung
The trachea is what air travels down to get to the lungs, it ends in bronchi which spread deep into the lungs to ensure that the air is evenly distributed in the lungs and also is to divide the lungs.
The bronchi get smaller and smaller and eventually they end in alveoli, which are on the outsides of the lung. Blood vessels pass near the outside of the lung and since the alveoli are so close to the outside, diffusion can occur. Alveoli also have moist outsides so that gases can dissolve to make diffusion more easy.
Carbon dioxide passes from the blood into the alveoli and the alveoli pass oxygen into the blood, that way both get what they want. The oxygen-filled blood goes back to the heart and the carbon dioxide in the alveoli is pushed out of the lungs and into the air.
[change] Bird Lung
Birds lungs do not have alveoli, instead they have millions of para-bronchi. These para-bronchi end up in tiny capillaries or very small blood vessels and they pass close to the body's blood vessels, so diffusion can occur and the oxygen and carbon dioxide is exchanged. The oxygen and carbon dioxide in birds lungs continuously be diffused into and out of the blood, not like mammals where diffusion can only happen in the alveoli.
[change] Reptile Lung
Reptile lungs open and close because of the ribs surrounding them pressing down on them and then opening up with the help of muscles. The liver is also attached to the bottom of the lungs and when a muscle which is attached to the liver pulls, the liver moves away from the lungs and pulls them, making them bigger.
[change] Amphibian Lung
Frog lungs are very simple compared to most other lungs, they are simply balloons, with moist outsides allowing for diffusion. But frogs do not move around much and so do not need lots of oxygen, but they can also take in oxygen through their moist outer skin if a big demand of oxygen is needed (e.g. Fight or Flight).
