Brown adipose

November 12, 2012

Brown adipose

What is “adipose”? It is tissue in the body that is used to store fat, and there are two different types of it. Firstly there is white adipose that is like a little pocket store of energy. By exercising and cutting down our calories, we force our bodies to use white adipose tissue for energy and thus our body fat decreases. Brown adipose tissue is similar in that it can also serve this purpose, but it also is able to create heat. Creating heat is actually the primary purpose of brown fat, and it also plays a crucial role in controlling weight. Although it is called brown, the colour can range from a deep red colour to a more tan colour depending on how many lipids it contains. The difference between white and brown fat is the number of iron-containing mitochondria present – the brown fat cells have a much higher quantity of these mitochondria than the white adipose tissue contain. The colder the environment, the darker the lipids in the brown tissue will be.

Brown adipose is most common in new babies, although it decreases as the child grows. Its presence is crucial especially in premature babies, as it stops the baby developing lethal illnesses as a result of cold such as pneumonia. Once the child grows, it is less crucial as things like the proportional surface area of the head lower significantly. If a human is cold it is much easier to detect the brown adipose, although the amount that is found will depend on whether the individual concerned is slim or obese. The healthier your weight, the more brown adipose tissue there will be. Mice have a large amount of this tissue well into their adult lives. Several studies have been conducted that indicate brown fat is a key component in remaining slim and burns more calories than white fat. However, it is more closely related to muscle than it is to white adipose tissue.

As brown adipose tissue burns energy stored in fat to get heat, it is most active when the human body is exposed to cold temperatures. This is because the cells contain a large amount of mitochondria – they are round and are deeply involved in heat generation. For this reason, the brown fat is particularly crucial to animals that live in colder environments as they need to stay warm yet might have the same coat as another of their species that resides in a warmer climate! The heat that is produced by these fat cells can be seen on infrared pictures.

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