Integumentary Accessory Structures: Nails

Within the integumentary system, four main accessory structures aid in thermoregulation, sense of touch, protection, and much more. These four main accessory structures are:

  1. Hair Follicles
  2. Nails
  3. Sebaceous Glands
  4. Sweat Glands

The nails can be found on the tips of your toes and fingers. The main function of these structures is to protect these areas from damage and the surrounding environment. They also function as a tool and aid in gripping things for picking them up, climbing, and most other things you do with your fingers.

The structure of your nail has two major parts, the area that is below the skin and the area above (visible). On the most distal portion of the finger, you have the free edge. This is the white area of the nail that is usually cut. This is the weakest part of the nail and can be broken or damaged very easily. Where the free edge meets the finger you have the hyponychium. The hyponychium is an area of skin that connects to the bottom of the free edge. The purpose of this structure is to prevent harmful things from entering the nail bed (germs, debris, etc.)

The major part of the external surface of your nail is called the nail body. It is sometimes referred to as corpus unguis and the nail plate. The nail body is the part of the nail that ranges from the free edge to the skin where your nail begins. This nail body is made of a specific type of keratin that makes it translucent as well as layers of dead cells that makes it strong and flexible.

Below the nail body is the nail bed. The nail bed functions to support the nail body during growth. The nail bed is made of tissues such as the hyponychium and the onychondermal. The onychondermal is the strongest attachment point between your nail and the underlying tissue. Both the onychondermal and hyponychium function for attachment and protection against pathogens and the surrounding environment.

The area that is at the base of the nail body is called the lunula. This structure is usually lighter and more white in color. It is also described as a half-crescent moon. The function of the lunula is to provide a defining change in structure between the nail edge and the root. Having a lunula usually means that your root matrix is working properly and well.

At the lateral edges of the nail body, where the nail meets your skin, the lateral nail fold begins. The lateral nail fold functions to aid in the protection of the finger on the lateral edges as well as aid in guiding the proper growth of the nail.

The area where the lunula meets the proximal nail fold is called the eponychium. This structure functions similarly to the hyponychium. It seals the passageway that would be present into the proximal nail fold and into the nail plate. This functions to prevent diseases, pathogens, and other harmful debris from entering parts of the nail that can become infected.

The proximal nail fold works in combination with the eponychium to prevent debris from entering the nail plate. It also functions similar to the lateral nail folds to guide and support nail growth. Finally, the nail fold protects the nail root and matrix that is present below this area.

The nail root is located within the epidermis several millimeters below the surface. The nail root place at which most of the nail is produced and where growth begins.

Rhinoceros: Horns More Valuable Than Gold

The Rhinoceros or Rhino is a part of a group of odd-toed land mammals that are located in Africa and Southeast Asia. These animals are known for the giant horns on their face. Many people believe that these horns are extensions of their skeletal system but, they are actually made of the same material as your hair and nails. The Rhino horn is made of a hardened form of keratin that makes it durable and strong for defense and intimidation.

You may often hear that rhinos are being hunted for their horns but, why is something that is made of the same material as our nails so valuable? The reason is first that Rhino horns are rare. There are an estimated 27,000 Rhinos left alive today and those numbers are decreasing. For this reason, acquiring a horn is extremely difficult to do. The other reason is that the Rhino horn is seen as a status material. This means that having the material increases your status in society and may make you a more powerful person in a community. Rhino horns are also used in medicine and are believed to have extremely powerful healing powers.

Rhinos are extremely large standing at heights of 6 feet and lengths of 13 feet. These massive creatures also have extremely thick and durable skin that allows them to survive attacks from other animals and travel through the harsh landscape they live in.