Sensations
A sensation (perception) is a conscious awareness of the stimulus. Because all the nerve impulses that travel away from sensory receptors into the central nervous system are alike, the resulting sensation depends on which region of the brain receives the impulse. For example, impulses reaching one region are always interpreted as sounds, and those reaching another are always sensed as touch.

Sensation requires the following steps:

1. There must be a stimulus originating either inside or outside of the body.
2. There must be a receptor capable of detecting the stimulus and of converting the stimulus into action potentials.
3. Action potentials generated by the receptor must be conducted to the central nervous system (CNS) through afferent nerves.
4. Action potentials reaching the CNS must be translated within the brain before the person is aware of the stimulus.