A special type of cell found right below the epidermis (top layer of skin). These cells are very close to the nerve endings that receive the sensation of touch and may be involved in touch. The cells also contain substances that may act as hormones.
Where is Merkel’s disk located?
Merkel’s disks are found in the upper layers of skin near the base of the epidermis, both in skin that has hair and on glabrous skin; that is, the hairless skin found on the palms and fingers, the soles of the feet, and the lips of humans and other primates.
How does Merkel disc work?
Merkel’s Disks are located superficially in the dermis of skin at the base of the epidermis, and lie adjacent to Meissner’s corpuscles and sweat glands. These receptors respond to indentation of the skin. They adapt slowly to pressure, and therefore record the sustained presence of pressure on the skin.
What is the difference between Merkel cells and Meissner corpuscles?
The main difference between Merkel cells and Meissner corpuscles is that the Merkel cells respond to the light touch whereas the Meissner corpuscles respond to the low-frequency vibrations. Furthermore, Merkel cells are slow-adapting while Meissner corpuscles are rapidly-adapting.
Does everyone have Merkel cells?
Merkel cells are found in the skin and some parts of the mucosa of all vertebrates. In mammalian skin, they are clear cells found in the stratum basale (at the bottom of sweat duct ridges) of the epidermis approximately 10 μm in diameter.
What’s Merkel cell carcinoma?
Merkel cell carcinoma is a very rare disease in which malignant (cancer) cells form in the skin. Sun exposure and having a weak immune system can affect the risk of Merkel cell carcinoma. Merkel cell carcinoma usually appears as a single painless lump on sun-exposed skin.
Are Merkel’s discs myelinated?
Microscopically they are relatively large, myelinated nerve endings. In hairy skin, Merkel nerve endings are clustered into specialized epithelial structures called “touch domes” or “hair disks”.
What do free nerve endings do?
Free nerve endings can detect temperature, mechanical stimuli (touch, pressure, stretch) or danger (nociception). Thus, different free nerve endings work as thermoreceptors, cutaneous mechanoreceptors and nociceptors.
What do nociceptors detect?
Nociceptors are sensory receptors that detect signals from damaged tissue or the threat of damage and indirectly also respond to chemicals released from the damaged tissue. Nociceptors are free (bare) nerve endings found in the skin (Figure 6.2), muscle, joints, bone and viscera.
Are Merkel cells free nerve endings?
The specialized mucosa covering the surface of the tongue with typically structured papillae and gustatory organs is free of Merkel nerve endings. In the mucosa of the anal canal, Merkel nerve endings can be found in nonkeratinized and keratinized parts.
Are Merkel discs free nerve endings?
Merkel’s disks are densely distributed in the fingertips and lips. They are slow-adapting, unencapsulated nerve endings, and they respond to light touch. Light touch, also known as discriminative touch, is a light pressure that allows the location of a stimulus to be pinpointed.
What are bulbous corpuscles?
The Bulbous corpuscle or Ruffini ending or Ruffini corpuscle is a slowly adapting mechanoreceptor located in the cutaneous tissue between the dermal papillae and the hypodermis. It is named after Angelo Ruffini.
