Major Regions, Neurons
The four major regions of the brain stem handle many of the body's basic life support functions, such as breathing, heart rate, eating and sleeping. Though small, the brain stem is an extremely important part of the brain because it lies between higher brain centers and the spinal cord. The nerve connections of motor and sensory systems from the cerebral cortex and cerebellum pass through the brain stem to the rest of the body.
Neurons, also known as nerve cells, are the information processing and transmission devices of the nervous system. Specialized neurons communicate specific kinds of information between different parts of the body and the brain. Sensory neurons respond to touch, sound, light, temperature, and other stimuli and send signals about these stimuli to the spinal cord and brain.
Motor neurons convert signals from the brain and spinal cord into muscle contractions or secretion by glands. Each nerve cell receives stimuli at branched nerve ending called dendrites and conveys information along cable-like extensions called axons.
Neurons communicate with other cells through electrical impulses. When a neuron is stimulated, it creates an electrical signal that moves from dendrites down the axon to the axon terminal. Arrival of the electrical signal causes the release of neurotransmitters—chemicals that act as messengers—from the neuron. These neurotransmitters pass across the synapse—the gap between a nerve cell and its target—and attach to receptors on the target cell. In the brain and spinal cord, these signals pass from neuron to neuron as the impulse travels to its destination—a vast and complex network that allows you to move, think, feel and communicate.