The appendages of the skin are derivatives of one of the layer of the skin, the epidermis. These appendages, namely the nails, sebaceous glands or oil glands, hair follicles and sweat glands play a unique but important role in keeping homeostasis of the body.
The Sweat Glands
The name sudoriferous glands also refer to the sweat glands. These glands are abundant in every person, numbering to over 3 million every person. They can be found anywhere in the body, except in some parts of the external genitalia and the nipples. There are two types of sweat glands known to exist, the eccrine and apocrine.
Between the two, the eccrine sweat glands or also referred to as the merocrine sweat glands, are much more abundant. Of all the parts of the body, they are particularly abundant in the soles of the feet, palms and the forehead. Sometimes, we associate the pores we found in our skin to the pores that secrete oil but those pores are actually external outlets of the hair follicles.
The eccrine glands are the ones responsible in the excretion of sweat. If one tastes the excreted filtrate, it may taste salty, hence deriving to the conclusion that sweat is mostly made up of salt but it contains much more than just a handful of salt. In fact, our sweat contains 99% water. The other 1% is made up of antibodies, vitamin C, metabolic wastes such as uric acid and ammonia, and trace amounts of sodium chloride. An interesting thing to note is our sweat contains a microbe-killing peptide called dermicidin. On normal occasion, the pH of sweat lies within 4 and 6.
Apocrine glands are confined in the regions of the axilla and the anogenital areas. In comparison to the eccrine glands, the apocrine glands are far larger. The composition of the excreted fluids of the apocrine glands is similar to that of the eccrine glands, with addition of some fatty substances and proteins.
The oil glands can be found anywhere in the body, except in the soles of the feet and palms of the hands. The sebaceous glands secrete sebum, which functions to moisten the skin and lubricate the skin. It also helps in preventing hair from becoming too stiff and brittle. Above all of these actions, perhaps the most important is its bactericidal action.
Hairs and Hair Follicles
Unlike other mammals, human hair is less luxuriant and useful to humans. Although it has diverse functions, the hair in our skin is mainly used for detection, that is to sense the presence of insects or other sharp objects before they come in contact with the skin. The hair on our scalp protects us from the sunlight and also to prevent hair loss. The eyelashes serve to protect our eyes and the hairs inside our nose are built to filter the air we breathe.
Much to our knowledge, the nail is actually an extension of the epidermis. The presence of nails helps protect the distal part of our fingers and our toes. It also aids the fingers when picking up things or scratching something.