Summary
Highlights
The brain, the most complex organ in the human body, coordinates all bodily functions as part of the nervous system. This three-pound mass of fat and protein is composed of four main regions: the cerebrum, cerebellum, brainstem, and diencephalon, each with specific tasks.
The cerebrum is the largest part of the brain, making up over 75% of its volume. It consists of neurons and nerve fibers that transmit information throughout the brain and body. It controls higher functions like learning, reasoning, speech, and senses such as sight and hearing.
Located under the cerebrum, the cerebellum is the second-largest part of the brain. It contains nerve cells and fibers, sending signals to other brain parts and the spinal cord. Its primary role is coordinating muscle movements, especially those maintaining balance and posture.
The brainstem, situated in front of the cerebellum, anchors the brain to the spinal cord. It includes the pons (carrying sensory information), the midbrain (controlling movement, auditory, and visual processing), and the medulla oblongata (creating motor and sensory pathways). Together, the brainstem parts control vital functions like cardiac activity, respiration, digestion, and sleep.
The diencephalon, located above the brainstem, forms the core of the brain. This apricot-sized region includes the thalamus (processing all senses except smell) and the hypothalamus and pituitary gland (producing and regulating neurochemicals). These structures govern sensations, weight regulation, energy, and instinctual behaviors like eating, drinking, and reproduction.
The brain protects itself with mechanisms like the blood-brain barrier, a semipermeable cellular wall allowing only specific chemicals to enter from the bloodstream. Despite this, complications such as tumors can lead to life-threatening issues. Maintaining brain health through physical activity and a balanced diet can preserve cognitive function and reduce the risk of diseases like Alzheimer's.