North American Registry of Midwives (NARM) Practice Exam

Which substance is produced by brown fat during thermogenesis?

1. Water

2. Heat

3. Carbon dioxide

4. Glucose

The correct answer is: Heat

Brown fat, or brown adipose tissue, is specialized for heat production, primarily through a process known as non-shivering thermogenesis. This process involves the uncoupling of mitochondrial respiration from ATP production, allowing for the generation of heat instead of usable energy in the form of ATP. The primary protein responsible for this is UCP1 (uncoupling protein 1), which facilitates the dissipation of the proton gradient generated during cellular respiration, resulting in the release of energy as heat. While the body does produce water, carbon dioxide, and glucose as part of various metabolic processes, none of these substances encapsulate the distinctive function of brown fat as effectively as heat does, particularly in the context of thermogenesis. The main role of brown fat is to generate warmth, especially in response to cold exposure or in newborns who have a higher need for heat production. Therefore, the distinctive contribution of brown fat during thermogenesis is accurately represented by heat.