A type of cells called ‘brown fat’ play an important role in generating heat to

Question

A type of cells called ‘brown fat’ play an important role in generating heat to maintain the body temperature of warm-blooded animals. They carry out cellular respiration as normal, with one exception: They express an ‘uncoupling protein’ that substitutes for the ATP synthase complex of proteins normally found at the end of oxidative phosphorylation. This ‘uncoupler’ allows the gradient of H ions generated by cell respiration to flow down their concentration gradient, from the mitochondrial intermembrane space to the mitochondrial matrix, without producing any ATP. Why would this produce heat that could warm the animal’s body?

Explanation / Answer

How Brown Fat Releases Heat:

Body heat is maintained by signaling the mitochondria to allow protons to run back along the gradient without producing ATP (proton leak). This alternative route for protons uncouples oxidative phosphorylation and the energy in the PMF is instead released as heat.

Cells of endotherms give off heat,when body temperature is below a regulatory threshold. Brown adipose tissue is highly specialized for this non-shivering thermogenesis.

Why it is important:

Brown fat releases heat when an organism, or body, needs extra heat. This can happen when a person is starting to have a fever, or when an animal awakens from hibernation. This heat generation, also called thermogenesis, is also triggered by feeding.

The function of the brown fat in newborn infants is to protect them from hypothermia, which is a drop in core body temperature. Hypothermia is a serious problem for premature newborns, and a major cause of death.

Older humans have a larger surface area, more muscle, a lower proportional surface area of the head, the ability to shiver, and the ability to move from cold areas. Newborns do not have this. High levels of brown fat in newborns provides an alternative way of regulating heat

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