Human brain
The human brain is the most complex organ in the body and the control center of the nervous system. Weighing about three pounds and composed of approximately 86 billion neurons, it governs every aspect of thought, emotion, behavior, and bodily function. Protected by the skull and suspended in cerebrospinal fluid, the brain processes sensory information, coordinates movement, regulates internal systems, and enables learning, memory, language, and consciousness.
The brain is divided into several major regions, each with specialized roles. The cerebrum, the largest part, is responsible for higher cognitive functions like reasoning, problem-solving, and voluntary movement. It is divided into left and right hemispheres and further into lobes that handle vision, touch, hearing, and decision-making. The cerebellum, located beneath the cerebrum, helps coordinate balance and precise motor control. The brainstem connects the brain to the spinal cord and regulates vital functions such as breathing, heart rate, and sleep.
The brain communicates through a vast network of neurons, which transmit electrical and chemical signals via synapses. Supporting these neurons are glial cells, which provide structural support, nutrition, and protection. This intricate system allows the brain to integrate information from the environment, make decisions, and generate responses in real time.
The human brain is also remarkably adaptable. Through a process called neuroplasticity, it can reorganize itself by forming new neural connections in response to learning, injury, or experience. This adaptability is key to development, recovery, and cognitive flexibility throughout life.
Understanding the brain remains one of science’s greatest challenges. Advances in neuroscience and neuroimaging continue to uncover how the brain functions in health and disease, offering insights into conditions such as Alzheimer’s, Parkinson’s, stroke, epilepsy, and mental illness. As research progresses, the human brain remains both a marvel of biology and a frontier of scientific discovery.