How do white fat cells differ from brown fat cells and from brite fat cells?

Question

What will be an ideal response?

Answer 1

The body has different types of adipose tissue and the quantities of each is determined by genes. White adipose tissue stores fat for other cells to use for energy; brown adipose tissue releases stored energy as heat, thus defending against cold and preventing obesity. In coupled reactions, the energy released from the breakdown of one compound is used to create a bond in the formation of another compound. For example, when fat is oxidized, some of the energy is released in heat and some is captured in the formation of ATP. Metabolism in brown adipose tissue differs; oxidation is uncoupled from ATP formation. In uncoupled reactions, all of the energy is released as heat. By radiating energy away as heat, the body expends, rather than stores, energy. In contrast, efficient coupling facilitates synthesis reactions, including the making of fat for storage. In other words, weight gains or losses may depend on whether the body dissipates the energy from an ice cream sundae as heat or stores it in body fat.
Brown fat and heat production is particularly important in newborn infants and in animals exposed to cold weather, especially those that hibernate. They have plenty of brown adipose tissue. In contrast, human adults have little brown fat, stored primarily around the neck and clavicle. Brown fat is most metabolically active during exposure to cold. Importantly, brown fat activity declines with age and with obesity; overweight and obese individuals have less brown fat activity than others. The role of brown fat in body weight regulation is not yet fully understood, but such an understanding may
prove most useful in developing obesity treatments.
Some white fat cells can undergo a process known as browning as they take on characteristics of brown fat, most notably the activity of uncoupled proteins; these fat cells are called brite adipocytes. Brite fat cells are far more abundant than brown fat cells in adults. By learning how browning is regulated, researchers hope to tilt energy balance from storage to expenditure in the effort to fight obesity. Interestingly, among the factors that trigger browning is physical activity. During exercise, muscle cells release a protein (the myokine irisin) that triggers the transformation of white fat cells into brite fat cells. Such findings help explain one of the many ways physical activity expends energy and supports weight management. Another factor gaining attention for its influence on the browning of white fat cells is the GI microbiota; the GI microbiota in people who are obese tend to be more limited in diversity and in activity than those in people who are not overweight