The human brain contains 5 main lobes - the frontal, parietal, temporal, and occipital lobes, as well as the brain stem. Each lobe is responsible for different cognitive functions - the frontal lobe is involved in reasoning and motor skills, the parietal lobe processes sensory information, the temporal lobe handles memory and language, and the occipital lobe processes visual information. The cerebellum and brain stem regulate vital body functions.