What does it do?
- Clean the warm air when it enters.
- Maximise the surface area for diffusion of oxygen and carbon dioxide between the blood and atmosphere.
- Minimise the distance for diffusion.
- Maintain adequate gradient for this diffusion.( in your exam refer to how shallow ot steep the gradient is)
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- Surrounded by pleural membrane.
- Space between the lung and membrane is filled with pleural fluid to allow friction free movment.
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Main areas in the lungs used for this process
- Trachea: has C shape rings of cartilages.( cartilages always keeps airways open and air resistance is lowto prevent collapsion or bursting of the lungs)
- Bronchi: has irregluar blocks of cartilages.
- Bronchiloes: surrounded by smooth muscles which contract and relax, and has no cartilage. They relax and widen during exercise.
- Alevoli: Air sacs at the end of Bronchiloe, they contain some collagen adn elastic fibres. Also are lined by epithelium, and the alveolar membrane is the gas exchange surface.
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- Gilia: they move the mucus contianing trapped foreign matter. Moving mucus up to the top of the trachea when it is swallowed, it goes down into the oesophagus.
- Globlet Cells ( produces mucus): Are part of the ciliated epthelium, and the upper part of each goblet cell is swollen with mucin made by the cells. Mucus is made of glycoprotein, this makes the mucus sticky.
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