On page 36, Dr Moalem discusses the body’s methods of generating and preserving heat when exposed to cold temperatures. Along with shivering and blood vessel constriction, the author also mentions the activation of brown fat, a tissue found in mammals used to generate heat. Brown fat can instantly convert blood sugar into heat for as long as the brown fat cell is provided with the sugar. Brown fat is useful because no muscle movement is required for the tissue to function; insulin isn’t required to bring sugar into the cells as well.
Using your own understanding of
lipids from the biochemistry unit as well as outside research, explain the structure
of brown fat and how the tissue works on a molecular level. Explain why brown fat is prevalent in newborns
and adults living in the extreme cold. How is brown fat being used today for
the treatment of obesity? Be sure to relate your response to Big Idea 2
(Biological systems utilize free energy and molecular building blocks to grow, reproduce,
and to maintain dynamic homeostasis).
(Christine Fanning, cfannin4@students.d125.org)
Fats are a type of lipid composed of glycerol and fatty acids. In Campbell fats are also described as having the alternate names triacylglycerol and triglyceride(75). Lipid droplets are cellular organelles that store lipids and are found in all eukaryotic organisms. These droplets store a large portion of mammalian fat in adipocytes or fat cells. This also gives brown fat its other name of Brown Adipose Tissue (BAT). According to Colorado University these lipid droplets are one of the big distinguishing features between white fat cells and brown fat cells. Brown fat cells contain many more smaller lipid droplets than the one large lipid droplet found in white fat cells. Brown fat also carries a large number of mitochondria. These mitochondria are what gives brown fat its ability to generate heat. This relates to Big Idea 2 because the large number of mitochondria use fats and sugars as sources of fuel to create energy which warms up the organism allowing the organism to maintain homeostasis.
ReplyDeleteBrown fat is used to heat up the body and defend against the cold. In the cold Moalem says that shivering is, "your body's first move"(35). However newborns often show an inability or reluctance to shiver making them more vulnerable to the cold. Newborns also have an inability to move away from cold areas. This vulnerability to the cold is the reason brown fat is needed as a defense against the cold and often makes up 5% of a newborns body mass. For adults living in the extreme cold brown fat is necessary to keep the body warm for extended periods in cold temperatures.
In many ways brown fat is a very inefficient way to treat obesity. Moalem says that a person would have to, "live in extreme cold for a few weeks"(37), for any significant amount of brown fat to appear. Brown fat would also disappear after a person left the cold environment. So while, brown fat does burn calories faster to produce heat, it much less efficient than diet options like running more and eating less.
While it is true that naturally causing brown fat to appear is time consuming and wasteful, there may be another option. Science Daily talks about that option in an article titled "Knowing how brown fat cells develop may help fight obesity". This article talks about the possibility of turning human white fat cells into brown fat cells. If this could be accomplished obese people could lose weight by creating more brown fat and burning calories.