Touch and Related Senses

How does the body sense touch, temperature, and pain?

Because nearly all regions of the skin are sensitive to touch, your skin can be considered your largest sense organ. Different sensory receptors in the body respond to touch, temperature, and pain. All of these receptors are found in your skin, but some are also found in other areas.

Touch Human skin contains at least seven types of sensory receptors, including several that respond to different levels of pressure. Stimulation of these receptors creates the sensation of touch. Not all parts of the body are equally sensitive to touch. The skin on your fingers, as you might expect, has a much higher density of touch receptors than the skin on your back.

Temperature Thermoreceptors are sensory cells that respond to heat and cold. They are found throughout the skin, and also in the hypothalamus, part of the brain that senses blood temperature. Recently, researchers studying the cell membrane proteins that sense heat made an interesting discovery. The chemical substances that make jalapeño peppers taste “hot” actually bind to these very same proteins.

Pain Pain receptors are found throughout the body. Some, especially those in the skin, respond to physical injuries like cutting or tearing. Many tissues also have pain receptors that respond to chemicals released during infection or inflammation. The brain, interestingly, does not have pain receptors. For this reason, patients are often kept conscious during brain surgery, enabling them to tell surgeons what sensations are produced when parts of the brain are stimulated.