What are Skin Sensors?-Definition and Types

Pain receptors are bare sensory nerve endings. They are present throughout the body of mammals. But they are absent in the brain and intestines. These nerve endings are also called nociceptors. Nociceptors are stimulated by severe heat, cold, irritating chemicals, and strong mechanical stimuli.

They send impulses to the brain. It interprets it as pain or itching. However, the detail of the structure and physiology of pain receptors is unknown.

Skin Sensors Of Heat And Cold (Thermoreceptors)

Sensors of temperature are also bare sensory nerve endings. Thermoreceptors are present in the epidermis or dermis. Mammals have different sensitive areas for cold or warm. These areas are called cold or warm spots. A small area of the skin that gives a temperature sensation is called cold or warm spots.

(a) Cold receptors respond to temperatures below skin temperature. For example metal is placed on the skin. It absorbs heat and we feel a sense of coldness.

(b) Heat receptors respond to temperatures above skin temperature. For example, wood is placed on the skin. It absorbs less heat. Therefore, we feel it warmer than metal.

Thermoreceptors In Snakes

The rattlesnakes and pit vipers have heat-sensitive pit organs. These organs are present on each side of the face between the eye and nostril. These pits are lined with sensory epithelium. This epithelium contains receptor cells. These cells respond to temperatures different from the surroundings. It is called infrared thermal regulation. Snakes use these pit organs to locate warm-blooded prey.

Skin Sensors Of Mechanical Stimulus

Many animals get information about their environment through mechanical receptors. Mechanical sensory receptors of vertebrates are present in the skin. They detect stimuli. The brain interprets it as light touch, touch-pressure, and vibration. The touching of skin gives light touch. In this case, the skin is not strongly deformed

Skin Receptors

There are the following skin receptors;

1. Bare sensory endings: They are receptors of light touch. Bare sensory nerve endings are the most widely distributed receptors in the vertebrate body. They are involved in pain, thermal stimuli, and light touch.

2. Tactile corpuscles or Meissner’s corpuscles: They also receive light tough stimulus.

3. Bulbs of Krause: They are mechanoreceptors. They are present in the dermis in certain parts of the body. They respond to some physical stimuli like position changes.

4. Pacinian corpuscles: They detect a touch-pressure stimulus.

5. Organs of Ruffini: They are also receptors of touch pressure.

6. Vibrissae: Many mammals have specially adapted sensory hairs called vibrissae. They are present on wrists, snouts, and eyebrows. There is a blood sinus around the base of each vibrissa. Nerves are present at the border of sinuses. They carry impulses from several kinds of mechanoreceptors and send them to the brain for interpretation.