Emergency Medical Technician (EMT) Intermediate Practice Exam

Which organ does NOT utilize insulin for glucose uptake?

1. Liver

2. Muscles

3. Brain

4. Fat tissue

The correct answer is: Brain

The brain is unique among the major organs in its method of glucose uptake, as it does not require insulin for this process. Instead, neurons rely on a different mechanism to transport glucose across their membranes. They have specific glucose transporters, such as GLUT1 and GLUT3, that allow glucose to enter the cells regardless of insulin levels. This characteristic is particularly important because the brain is a highly energy-demanding organ that requires a constant supply of glucose to function properly, especially during periods when insulin levels may be low or in cases of insulin resistance. The other organs listed—liver, muscles, and fat tissue—all utilize insulin in their processes for glucose uptake. The liver, for instance, can store excess glucose as glycogen or convert it into fatty acids in the presence of insulin, while muscle and fat tissues use insulin to enhance the uptake of glucose, especially during times of increased energy demand or after food consumption.