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Breathing and the lungs.

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The lungs are like big air sacs. They are situated in the thoracic cavity. The lungs are very large and spongy. They have a big inside surface area. They're moist and they have a good blood supply. The lungs are protected by the rib cage and situated above the diaphragm muscle. I know from studying GCSE Biology that we breathe in air through our nose and mouth. It is much safer for us to breathe through our nose rather than our mouth. This is because of the tiny hairs that are present in our nose. This causes the air coming in to be cleaned, heated and moistened therefor the air is much cleaner going into our lungs. Once the air has entered through our nose or mouth it travels down our wind- pipe which is also known as the trachea. ...read more.


When we breathe IN the intercostal muscles CONTRACT. These muscles move the ribcage UPWARDS increasing the volume o f Oxygen present in the lungs. The diaphragm moves DOWNWARDS, which makes it flatten out this therefore making the chest larger. My tutor gave me these diagrams from the "Biology for you" teachers handbook. When we breathe OUT the intercostal muscles RELAX. The ribcage LOWERS and the chest decreases in volume. The diaphragm relaxes and moves UPWARDS back into its original position. The exhaled air is then forced out of our lungs and into the outside world. A simple and quick way to show how the lungs operate is to use the Bell jar model. The bell jar itself represents the ribcage, which protects the lungs. ...read more.


Is this model a perfect model of the lungs? Although this is the most suitable model of the lungs that I could find there are reasons why this is not a good representation. * Firstly the bell jar that represents the rib cage does not move. I know that when I breathe the ribcage moves up and down and in and out but the model does not show this. * The rubber sheet would not lie flat across, it should lie in a concave shape just like the actual diaphragm does. * There would not be as much space in the lungs as there is in the jar. I know that when I breathe in the lungs take up the whole space of the ribcage but the balloons do not demonstrate this. ...read more.

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