skin

• skin 


  is the largest organ in our body discriminates five kinds of sensations; tough, pressure, warmth, cold, and pain
• skin has three layers:

  -          epidermis (outer layer)

  -          dermis (intermediate layer)

  -          subcutaneous adipose tissue (deep layer)
• sensory receptors located around the roots of hair cells appear to fire in response to touching the surface of the skin
• use methods such as the two point thresholds to assess sensitivity to pressure

  -          as revealed by this method, our fingertips, lips, nose, and cheeks are much more sensitive than our shoulders, thighs, and calves
• Temperature


  -          the receptor for temperature are neurons beneath the skin

  -          when the skin temperature increases, receptors for warmth fire
• Pain


  -          pain is a signal that something is wrong in the body

  -          pain is adaptive in the sense that it motivates us to something about
• the pain message to the brain is initiated by the release of various chemical including prostaglandins which not only facilitate transmission of the pain message to the brain but also heightens circulation to the injured area, causing redness and swelling called inflammation
• analgesics 


  -          such as aspirin and ibuprofen work by inhibiting prostaglandin production
• gate theory


  prevents to transmit signals to the brain due to the limited amount of stimulation that can be processed by the nervous system at a time