Tuesday, November 10

Skin senses - human skin senses of pain, touch, cold and warm

Human skin senses

Human skin senses

In humans, pain (including itch), cold, warm and touch (including light pressure, deep pressure, vibration and tickle) are perceived by different nerve endings. Skin, the largest and most exposed organ of human body, is endowed with numerous sensory nerve endings.
One square centimeter of human dermis has up to fifty receptor endings for pain, cold, warm and touch. These nerve endings can perceive one or more of senses like touch, pressure, cold, warm and pain. Some areas like tip of the fingers, lips and tongue have more touch receptor endings in human body. There are many types of nerve receptor endings in human skin having specific functions of senses.

Ruffini endings
  • Ruffini corpuscle is a slowly adapting mechanoreceptor existing in the human subcutaneous tissues.
  • This receptor is spindle shaped and perceives the stimulus of stretch and touch.
  • It monitors the slippage along the skin and helps the mechanism of gripping a object.
The Ruffini ending
The Ruffini ending (enlarge)

Meissner's corpuscles
  • Meissner's corpuscles are rapidly adapting mechanoreceptors having highest sensitivity and they convey the senses of light touch.
  • Though they are distributed throughout the human skin, they are more concentrated in fingertips, lips, tongue, soles and palms in human body.
  • They are located primarily just below the epidermis and convey the feeling of touch.
Meissner's corpuscles (sensory nerve ending for touch)
Meissner's corpuscles (sensory nerve ending for touch) (enlarge)

Pacinian corpuscles
  • Pacinian corpuscles are mechanoreceptors in the human skin responsible for pain and pressure senses.
  • This receptors are larger and are fewer in number. The corpuscle about one mm in length and is covered by connective tissue.
  • At the center of the corpuscle is the inner bulb with fluid filled cavity having a single receptor ending without myelin and transmit pain.
Pacinian corpuscles
Pacinian corpuscles (enlarge)

Merkel nerve endings
  • Merkel nerve endings are found in human skin and mucosa providing pressure and texture senses to the brain.
  • The nerve ending consists of Merkel cell and enlarged nerve terminal. These are categorised as slow adapting mechanoreceptors.
Free nerve ending
  • Free nerve ending is unspecialised nerve ending passing on skin pain senses to the human brain.
  • Thermoreceptors are nerve endings in skin conveying the warm and cold perceptions to human brain.
  • There are separate receptors for carrying the warm and cold senses.
  • The warmth receptors are slower in transmitting the impulses when compared to cold receptors.
  • Nociceptors are receptors that react and convey to human brain the senses of pain. These are specialised pain sensors.
Bulboid corpuscle
  • Bulboid corpuscles are skin receptors which can detect low frequency of vibrations.
    These are minute oval or cylindrical bodies consisting of soft core.
Bulboid corpuscle
Bulboid corpuscle (enlarge)

Hair follicle endings
  • Hair follicle endings respond to displacement of hair and touch senses and are present in hairy areas of the human skin.

Current topic: Human skin senses

Get glowing skin complexion. Remove acne scars and blemishes from face.

No comments: