Adipose tissue and its types

Fatty tissue is a special connective tissue that functions as the main storage for fat in the form of triglycerides. In humans, it is present in two different forms: white and brown. Its number and distribution are individual.

White fatty tissue performs three functions: thermal insulation, a mechanical cushion and, most importantly, a source of energy. Basically, it is directly under the skin and is the main heat insulator of the human body, because it conducts heat three times worse than other tissues. The degree of insulation depends on the thickness of this layer. For example, a person with a 2-mm layer of subcutaneous fat will feel as comfortable as possible at 15 ° C, whereas with a 1 mm-16 ° C. In addition, the fat tissue surrounds the internal organs and provides them with protection against concussion.

For example, it is located:

- around the heart;

- in the kidneys;

Filling around the joints;

- inside the eye socket, behind the eyeball, etc.

As the main storehouse of energy, it provides its stock with excess consumption. Consequently, more energy can be obtained from a gram of fat (9 kcal) than from a gram of carbohydrates (4 kcal) or protein (4 kcal). In addition, if a person stored excess energy in the form of carbohydrates, an increase in mass would interfere with his mobility.

However, there are some restrictions on the use of fat as a "fuel". Thus, tissues that function primarily through anaerobic processes (eg, erythrocytes) should receive energy from carbohydrates and should have sufficient supply of them. In addition, under normal conditions, the brain depends on glucose and does not use fatty acids. In unusual metabolic circumstances, he can use ketone bodies (a by-product of incomplete fat metabolism) if they are present in fairly large quantities.

The brown fatty tissue got its name due to the color caused by the rich vascularization and tightly packed mitochondria, which can be found in various places.

Instead of serving as a substrate, the lipids in it release energy directly in the form of heat. The mechanism of its generation is associated with metabolism in the mitochondria.

The biochemical process of energy release in the form of heat is activated in those cases when the overall body temperature begins to decrease. In response to hypothermia in the human body, hormones are released that stimulate the release of fatty acids from triglycerides, which in turn activate thermogenin.

In humans, the formation of brown adipose tissue begins at the 20th week of intrauterine development. At birth, it is approximately 1% of body weight. Its layer is located around the blood vessels supplying oxygen to the brain and organs of the abdominal cavity, and also surrounds the pancreas, adrenals and kidneys. Thanks to the brown adipose tissue, the vital organs of the newborn are not supercooled in a low-temperature environment.

After birth, the child begins to develop white fat tissue, and the brown begins to disappear. An adult does not have places of her cluster, although she is present (about 1% of the mass of fat), but chaotically mixed with white.