How the Human Brain Works

The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sense organs, and making decisions as to the instructions sent to the rest of the body.

The brain is contained in, and protected by, the skull bones of the head. The cerebrum is the largest part of the human brain. It is divided into two cerebral hemispheres. The cerebral cortex is an outer layer of grey matter, covering the core of white matter. The cortex is split into the neocortex and the much smaller allocortex.

Neurons send signals to other cells as electrochemical waves travelling along thin fibers called axons. When a wave reaches a junction called a synapse, it triggers the release of chemicals called neurotransmitters. These chemicals diffuse across the very small gap between two neurons and bind to receptors on the surface of the target cell.

The adult human brain is estimated to contain 86 billion neurons and roughly the same number of non-neuronal cells. Each neuron is connected by synapses to up to 10,000 other neurons.