Touch (Encyclopedia of Psychology)
The skin sense that allows us to perceive pressure and related sensations, including temperature and pain.
The sense of touch is located in the skin, which is composed of three layers: the epidermis, dermis, and hypodermis. Different types of sensory receptors, varying in size, shape, number, and distribution within the skin, are responsible for relaying information about pressure, temperature, and pain. The largest touch sensor, the Pacinian corpuscle, is located in the hypodermis, the innermost thick fatty layer of skin, which responds to vibration. Free nerve endingseurons that originate in the spinal cord, enter and remain in the skinransmit information about temperature and pain from their location at the bottom of the epidermis. Hair receptors in the dermis, which are wrapped around each follicle, respond to the pressure produced when the hairs are bent. All the sensory receptors respond not to continued pressure but rather to changes in pressure, adapting quickly to each new change, so that, for example, the skin is unaware of the continual pressure produced by clothes. Once stimulated by sensation, the receptors trigger nerve impulses which travel to the somatosensory cortex in the parietal lobe of the brain, where they are transformed into sensations. Sensitivity to touch varies greatly among different parts of the body. Areas that are highly sensitive, such as the fingers and lips, correspond to a proportionately large area of the sensory cortex....
(The entire section is 649 words.)
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