Difference Between Brown and White Adipose Tissue

Main Difference – Brown vs White Adipose Tissue

Brown and white fat tissue are two types of fat cells found in the body. Fat cells are also called the adipocytes. Both brown and white fat cells secrete both immune system messengers and important hormones for the functioning of the body. Both types of adipose tissue are made up of loose connective tissue. The main difference between brown fat and white fat is that brown adipose tissue is a less common type of fat in the body that is thermogenic whereas white adipose tissue is the most abundant and non-thermogenic. Brown adipose tissue in newborns and small mammals help to survive in cold temperatures.

Key Areas Covered

1. What is Brown Adipose Tissue
     – Definition, Facts, Role
2. What is White Adipose Tissue
     – Definition, Facts, Role
3. What are the Similarities Between Brown and White Adipose Tissue
     – Outline of Common Features
4. What is the Difference Between Brown and White Adipose Tissue
     – Comparison of Key Differences

Key Terms: Adipocytes, Brown Adipose Tissue, Fat Droplets, Mammals, Thermogenic, White Adipose Tissue

What is Brown Adipose Tissue

Brown adipose tissue (BAT) refers to a dark-colored adipose tissue, with many blood vessels, which rapidly produces heat in infants and small mammals. Notably, BAT only occurs in mammals. The main function of the Brown adipose tissue is the transfer of energy from food into heat, is regulated by epinephrine. Two types of BAT can be identified based on their location in the body. The classical BAT can be found between the shoulder blades (interscapular). This BAT shares a common origin with muscle cells. Another BAT is found under the skin (subcutaneous). This BAT originates from the white adipose tissue. The brown adipose tissue in humans is shown in figure 1.

Figure 1: Brown Adipose Tissue

The BAT contains numerous fat droplets and many mitochondria. This gives the brown color to the BAT. Numerous capillaries supply oxygen to produce heat. As BAT helps to burn calories of the body, it is more often called as ‘good fat’. The white adipose tissue can be converted into BAT by exercising. Getting enough sleep leads to the proper production of the BAT. Getting exposed to the cold regularly may also increase the production of brown fat.

What is White Adipose Tissue

White adipose tissue (WAT) refers to a type of loose connective tissue composed of white, lipid-filled cells. WAT is the most common type of adipose tissue in the body. 20% of the total weight of a man is White adipose tissue. The cytoplasm of the white adipose tissue occurs as a narrow rim, and the nucleus of the cell is pressed near the margin. The fat cell consists of a single, large fat droplet. WAT is found under the skin and around the organs. WAT under the skin is shown in figure 2.

Figure 2: White Adipose Tissue

The main function of WAT is to store energy. Other than that, it secretes hormones such as leptin, asprosin, and adiponectin. WAT also provides insulation and mechanical cushioning to the structures of the body. In mice, WAT is converted into BAT under the influence of the hormone, irisin. Same as Bat, the WAT can be only found in mammals.

Similarities Between Brown and White Adipose Tissue

• Brown and white adipose tissue are two types of fat cells found in the body.
• Both brown and white adipose tissue are made up of loose connective tissue.
• Both brown and white fat cells secrete both immune system messengers and important hormones for the functioning of the body.

Difference Between Brown and White Adipose Tissue

Definition

Brown Adipose Tissue: Brown adipose tissue is a dark-colored adipose tissue which rapidly produces heat in infants and small mammals.

White Adipose Tissue: White adipose tissue is a type of loose connective tissue composed of white, lipid-filled cells.

Location

Brown Adipose Tissue: The brown adipose tissue is found in shoulder blades and under the skin.

White Adipose Tissue: The white adipose tissue is found under the skin and around the organs.

Cytoplasm and Nucleus

Brown Adipose Tissue: The cytoplasm of the brown adipose tissue occurs throughout the cell, and the nucleus can be found at the center of the cell.

White Adipose Tissue: The cytoplasm of the white adipose tissue occurs as a narrow rim, and the nucleus of the cell is pressed near the margin.

Fat Droplets

Brown Adipose Tissue: Brown adipose tissue is multilocular.

White Adipose Tissue: White adipose tissue is unilocular.

Number of Mitochondria

Brown Adipose Tissue: Brown adipose tissue consists of many mitochondria.

White Adipose Tissue: White adipose tissue consists of a few mitochondria.

Vasculature

Brown Adipose Tissue: Brown adipose tissue is highly vascularized.

White Adipose Tissue: White adipose tissue comprises relatively few capillaries.

Thermogenic/Non-thermogenic

Brown Adipose Tissue: Brown adipose tissue is thermogenic.

White Adipose Tissue: White adipose tissue is non-thermogenic.

Characterized by

Brown Adipose Tissue: Brown adipose tissue is characterized by the presence of leptin.

White Adipose Tissue: White adipose tissue is characterized by the presence of UCP-1.

Function

Brown Adipose Tissue: Brown adipose tissue produces heat.

White Adipose Tissue: White adipose tissue serves as a depot that provides insulation and mechanical cushioning.

Conclusion

Brown and white adipose tissue are two types of fat found in mammals. The main type of fat is WAT. The BAT produces heat while WAT serves as an energy store. The main difference between brown and white adipose tissue is their role in the body.

Reference:

1. Adipose Tissue, Biology Papers, Available here.
2. Cannon, B, and J Nedergaard. “Brown Adipose Tissue: function and physiological significance.” Physiological reviews., U.S. National Library of Medicine, Jan. 2004, Available here.
3. “White adipose tissue.” Wikipedia, Wikimedia Foundation, 26 Dec. 2017, Available here.

Image Courtesy:

1. “Brownfat PETCT” By Hg6996 – Own work, Public Domain) via Commons Wikimedia
2. “Blausen 0012 AdiposeTissue” By Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work (CC BY 3.0) via Commons Wikimedia

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