|MadSci Network: Anatomy|
Dear Dee, I encourage you to keep asking questions about your reading. Many times books will suggest areas for questions that may not be covered in the text. Keep up the good work! Fat is the way people, and animals, store some of the extra food they have eaten. Because the fat does not have another routine job, like the muscles and bones do, the fat deposits do not have very many blood vessels in them. Anything that slows down the heat escaping from your body helps keep you warm. That is why you wear more clothes when it is cold outside. Clothes slow down the heat loss from your body to the air around you. Your fat layers perform the same work because of the low blood flow through them. The fat keeps some of your blood from getting too close to the skin where it can quickly lose heat. The result is almost like carrying a blanket around with you under your skin. One large, thick layer of fat is just under the layers of muscle across your abdomen (stomach area). There are a lot of blood vessels in your abdomen associated with your intestines and other internal organs. This fat layer, called the greater omentum, is a very good use of body fat to preserve body heat. People whose ancestors developed in cold climates (like the Eskimos of the Arctic), have more body fat and the fat is distributed over much of their bodies uniformly. This protects more of their bodies from heat loss. People whose ancestors developed in hot climates (like the African natives), have fat deposits in more localized parts of their bodies, leaving large areas of skin with many blood vessels near the skin. This allows these people to cool off more quickly if they become overheated. You also asked if there are any other ways fat helps keep us warm. Fat is the most concentrated source of energy of the three basic food types (fat 9 calories per gram, protein 4 calories per gram, and carbohydrates 4 calories per gram). Your body burns some of your stored fat when you have not eaten enough food to supply all of your body's needs. So, not only does a fat layer help keep you warm by preventing heat loss to the air but it is one of the primary fuels that your body burns to produce the heat in the first place! I hope this helps.
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