Discovery Science: Human – Sensory Organs – Skin

Earth Science: Human – Sensory Organs – Skin

Tactile senses allow for the conscious sensation of stimuli such as touch, pressure, temperature, pain, and vibration. The skin is not equally receptive to stimuli, but sensitive at certain points containing sensory receptors.

Tactile senses can be divided into the sense of touch, the sensation of hot or cold temperature, and the sense of pain. The receptors responsible for the sense of touch (mechanical receptors) are distributed across the body at different densities. The fingertips or lips, for example, have a lot of tactile receptor points, while the back, the upper arms, and thighs have only very few.

Mechanical receptors can be divided into various types: Merkel’s tactile disks and Meissner’s corpuscles are stimulated when the skin changes shape; the Pacinian corpuscles, which are especially plentiful at the fingertips, react to pressure and vibration.

The human heat and cold receptors (thermoreceptors) are not only responsible for the reception and transmission of stimuli, but also play an important role in thermoregulation. They are very common in the face and especially in the region of the mouth where they form an almost continuous area.

Since receptor cells for heat sensation are stimulated by high temperatures and receptor cells for cold sensation are stimulated by low temperatures, most people perceive water of a certain temperature as warmer or colder depending on which temperature the skin was exposed to prior to contact with the water.

Sense of pain The human body is equipped with nociceptors, sensory receptors that can sense pain. These branched-out nerve ends inside the skin transmit pain stimuli to the central nervous system.

If tissue is damaged, for example, due to bruising, cuts, or burns, the affected cells release messenger substances that trigger certain reactions in the nociceptors.


Although the tactile sense is usually the east developed sense in humans, it can be trained very effectively to perform at higher levels. Visually impaired people do this when they learn the Braille system.

This way of writing was developed in 1825 by Louis Braille (1809-1852) who was already fully blind as a small child. He invented a system of letters composed of six raised dots which can be read by touching the symbols with the fingertips.


MUTATION PREVENTS PAIN Just one single mutation can be enough to render a person extensively insensitive to pain. Six children from three families in northern Pakistan are affected by this mutation.

Their lack of a normal sensation of pain has its downsides, as an important warning system of the body is not functioning. Several bone fractures remained unnoticed by the children.