Physiology Of Human Fat Cells

Human fat cells -- also called adipocytes -- represent a type of loose connective tissue. The cells occur naturally in several regions in the body and serve a number of purposes. Scientific research has uncovered several facts about the physiology of human fat cells, giving insight into their distribution and role within the human body, as well as their role in disease.

Appearance and Development

When observed under a microscope, most fat cells appear large and round. The cells fail to take up significant tissue stain and therefore appear white in prepared slides. Each adipose cell contains a single large droplet of fat that takes up the majority of the cell, with the other regions of the cell flattened near the cell's membrane. The cells occur in a number of tissues, including bone marrow, skin and around the kidneys.

Fat cells develop from less-specialized cells called fibroblasts -- a type of flattened cell abundant in your body. As part of tissue maintenance, fibroblasts can develop into fat cells or other connective tissue types to suit the needs of your body. Once created, they remain in your body unless surgically removed, though the size of the cell can change as the fat droplet inside the cell grows or shrinks.

Function

The major function of human fat cells is to store energy, and they provide a rich source of chemical energy. One gram of fat contains, on average, 9 calories worth of energy, compared with 4 calories for carbohydrates or proteins. As a result, fat tissue provides an efficient means of energy storage. If you consume less energy than you burn each day, your body begins to break down the fat molecules within your fat cells as a source of energy, causing weight loss. Fat cells also have a role in hormone production within your body, producing compounds that affect your appetite, as well as your body's responses to insulin, according to Texas Tech University.

Role In Disease

Human fat cells play a significant role in disease. Among the most prevalent diseases associated with fat cells is obesity, or excess body weight. Obese individuals often develop fatty deposits around their organs, including their heart, as well as large fat deposits under their skin. Overall, the excess fat can impede organ function, as well as increase the risk of heart disease, some forms of cancer and diabetes. Physical activity and maintaining a healthy diet can help prevent excess fat storage and obesity.

Brown Vs. White Fat

Though the vast majority of fat cells within your body are white fat cells, there is a second type of fatty tissue -- called brown fat -- present in small amounts in your body. You are born with approximately 5 percent brown fat, and this amount decreases as you age. Brown fatty tissue appears darker than white fat, due to the complex and abundant network of blood vessels not found in white fat. The cells also appear distinct from white fat under the microscope, containing several small fat droplets instead of a single large droplet found in white fat. Brown fat appears to play a role in maintaining your body temperature and the release of energy as heat, though the cells might have additional functions not yet identified.

Despite accounting for less than 5 percent of human fatty tissue, brown fat appears to play a role in your health. Colorado State University explains that individuals with more brown fat tend to maintain a lower body weight relative to their height, while individuals with less brown fat experience a higher incidence of obesity. The specific role of brown fat -- as well as its potential in treating obesity -- remains unclear and is still under investigation.