The adipocytes are not just fat-storing cells. They participate very actively in the total metabolism. They combine to form polynuclear cells, whereby the individual cells of the network are connected via so-called gap junctions.
There are two types of adipocytes. These are the univacuolar and the plurivacuolar adipocytes. The univacuolar adipocytes represent the white adipose tissue and contain only one vacuole, which has the task of storing fat. The vacuole can take up to 95 percent of the cell volume, pushing the other cell organelles and the nucleus to the edge of the cell. Thus, for the most part the cell consists of storage grease. The plurivacuolar adipocytes belong to the brown adipose tissue and have several vacuoles that can be filled with storage fat. However, these do not push the other organelles to the cell edge.
They have many mitochondria that burn the fat directly inside the cell, generating heat. The brown adipose tissue becomes active, for example, during cooling. By burning fat, the organism ensures the maintenance of body temperature. The ratio of brown to white adipose tissue is crucial for energy consumption. However, in adult humans, brown adipose tissue hardly plays any role, so that fat reduction can not be based on its activation.
The most important task of adipocytes is the storage of body fat. This is mainly the white adipose tissue responsible. To a small extent, energy is generated by burning fat in brown adipose tissue. The energy production within these cells is independent of the general energy metabolism of the body.
They only serve to maintain the body temperature with a decrease in the outside temperature. For this purpose, the fat stored in the adipocyte is burnt directly. In humans, this function is normally only relevant in the infant. Later, the brown adipose tissue atrophies. However, there may be some people who can not gain weight because they still have a relatively high amount of brown adipose tissue. However, research has shown that the role of adipocytes is much more complex than the function of fat storage suggests. The adipose tissue is the largest endocrine organ, which very actively intervenes in the metabolism. The amount of stored fat plays a very important role.
Among other things, the adipocytes in addition to many hundreds of active ingredients produce three important hormones that regulate the metabolism. These are the hormones leptin, resistin and adiponectin. Leptin inhibits the feeling of hunger. The more storage fat the adipocytes contain, the more leptin is secreted. An additional administration of leptin to produce the feeling of satiety is unsuccessful, because the leptin content of an obese man is already high and the additional administration shows no effect. Resistin and adiponectin control insulin resistance.
The more fat stored in the adipocytes, the lower the concentration of adiponectin. However, adiponectin promotes insulin sensitivity. Conversely, resistin increases insulin resistance. How these hormones can be used therapeutically in diabetes needs further investigation.
As a rule, the number of adipocytes remains the same throughout life. Only the volume of the cells changes when fat is stored or dispensed. An adipocyte can store a maximum of 1 microgram of fat. When the absorption capacity of all adipocytes present in the body is reached and still more fat is built up than is broken down, cell divisions are initiated in the case of the preadipocytes, the so-called steatoblasts.
From the steatoblasts develop new adipocytes. The number of fat cells increases in this case. However, the adipocyte count remains the same for fat reduction. The newly formed small fat cells are insulin-sensitive in contrast to the existing adipocytes. After differentiation of the new fat cells, these too become insulin resistant again.
Obesity has become a common disease. The more fat is stored in the adipocytes, the greater the risk of developing Type II diabetes.
Diabetes, in turn, is an underlying disease for many degenerative processes in the body. Finally, the metabolic syndrome may develop with a complex of disorders such as obesity, diabetes, lipid metabolism disorders, arteriosclerosis and cardiovascular disease. During the development of obesity, insulin resistance decreases over time. Insulin ensures that blood sugar, fatty acids and amino acids are channeled into the body's cells in order to generate energy or to build up the body. Excess energy that is not consumed stores the adipocytes in the form of fat. Hormonal processes in fat cells in turn control insulin resistance to limit the unlimited supply of glucose.
This process is actually normal. However, he gets out of control, if still calories are supplied, which can not be stored anymore. Insulin resistance develops into a chronic condition. Although insulin is produced in large quantities. However, it is becoming less and less efficient. The blood sugar level rises. The pancreas is even more stimulated for insulin production. This goes on until exhaustion of production occurs. Now the relative insulin deficiency due to insulin resistance becomes an absolute insulin deficiency. It has developed a manifest diabetes with all its consequences.Tags: