Can anyone direct me to a site where I can download a free 3D model with a skeleton so I can practice using them in the XNA environment untill I'll make my own models? 

If the model is human-ish (2 legs , 2 hands and stands up) that would be great!


Question: Does the lung absorb organic food?
Answer: When we eat the architecture makes sure most if not all the food ends up in our foodpipe rather than our windpipe. This is aided by a structure called the epiglottis. 

However frequently foods may be inhaled, for example if a drink is sucked through a straw more if it gets into the lungs compared to if we drink it. Occasionally we will inhale a peanut or something else which typically occurs due to abnormal relaxation or muscular problems in the structures involved. This may be due to a neurological disease (e.g. myasthenia gravis) or because simply drinking too much and inhaling peanuts or vomit (aspiration). 

If the inhaled substance is small and lipid soluble e.g. alcohol, it can pass through the alveoli at the end of the lung to the rich blood supply. If it doesn't we rely on macrophages to digest the food. They aren't frequent enough to digest anything substantial. Bacteria however are great at munching this up and increase substantially in number. Typically your lowest airways are sterile but food can interfere with clearance mechanisms and provide a home. The part of the lung blocked (distal to the foreign object) can collapse and frequently does. In the long run this may cause bronchiectasis, where an infection recurrently affects the area due to permanent damage done during the initial event resulting in widened airways and an ongoing inflammatory response. The inflammatory response reveals even more receptors for bacteria to latch on to.