The brain has three main regions - the forebrain, midbrain, and hindbrain. The cerebrum is the largest part and regulates senses, memory, emotions, intellectual activities, and body movement. The forebrain includes the cerebrum, thalamus, hypothalamus, and limbic system. The brainstem connects the cerebrum and cerebellum to the spinal cord and regulates vital functions for survival like breathing and heart rate. The limbic system is involved in feelings while the brainstem ensures safe behavior for survival.