Section VII. FATTY TISSUES
Another supportive tissue of the body is fatty tissue (fat connective tissue). Here,
the matrix is a lipid material, but found within the cell rather than outside of the cell.
Lipids are fats, oils, and similar compounds such as fatty acids. Lipids are stored
mostly in the form of neutral fat. Neutral fat consists of triglycerides, a type of molecule
formed from glycerol (a type of alcohol) and three fatty acids. According to the length of
each fatty acid, the triglyceride may be a liquid (oil) or a solid (fat). The triglycerides are
kept in a liquid form, and even in cold weather, their lengths are adjusted in order to
maintain a liquid state.
2-30. BROWN FAT AND YELLOW FAT
There are two types of fat within the body---brown fat and yellow fat. Both are
excellent means of energy storage. When metabolized, they both yield large amounts
of energy, especially when compared to carbohydrates. Brown fat is more common in
infants and children, whereas adults tend to have mostly yellow fat.
2-31. TURNOVER OF FATS
Fats are essentially a temporary storage phenomenon. There is a continuous
turnover of the triglycerides. There is a complete turnover within a 3-week period.
The diet is the major source of fat in the human body. Fats may be taken in as
fats or converted from other substances, such as carbohydrates.
Obesity occurs when excessive amounts of fats and/or carbohydrates are taken
into the body. When the energy contained in these compounds is not used in bodily
activities, the surplus is generally stored as the triglycerides in fatty tissues of the body.
2-34. STORAGE OF FAT-SOLUBLE SUBSTANCES
a. A number of fat-soluble substances may be stored in the fat of the body.
Vitamins A and D are fat-soluble.