What part of the human brain makes up approximately 80 percent of its weight?

The cerebrum is the largest part of the human brain and comprises approximately 80 percent of its total weight. This significant size is due to its role in various complex brain functions, including reasoning, problem-solving, emotional responses, learning, and sensory perception. The cerebrum is divided into two hemispheres and further subdivided into lobes, each responsible for different functions such as movement, touch, sight, taste, and sound.

In contrast, the cerebellum, while essential for coordination and balance, constitutes a much smaller portion of the brain. The brainstem, which connects the brain to the spinal cord, manages vital functions such as breathing and heart rate but also occupies a smaller volume. Lastly, the thalamus acts as a relay station for sensory and motor signals but is not substantial enough in size or weight to account for the majority of the brain's mass. Thus, the cerebrum's overall structure and function justify its status as the most prominent component of the human brain.