A neuron, also known as a nerve cell, detects stimuli in its environment, integrates the information and then decides whether or not to transmit a signal to the next cell. There are three varieties of neurons: sensory neurons, motor neurons and interneurons.
Sensory neurons detect environmental stimuli, such as light, sound, heat and pressure, as well as chemicals, such as acids, bases, sugars and salts. Motor neurons transmit signals to effector cells. These can be thought of as output cells and include cardiac and skeletal muscles, sweat glands, cells of the gastrointestinal tract and endocrine tissues. Around 99 percent of neurons are interneurons. They relay information from sensory neurons to the next cell in line a motor neuron or another interneuron.