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What Is the Integumentary System?
As an organ system of the human body, the integumentary system is mainly composed of the skin, nails, hair, glands and nerves. In some animals, feathers and scales are also part of the system. The main purpose of the integumentary system is to protect the inner tissues of the body.
Besides protection, the integumentary has several other functions as well which we discuss more in detail. The integumentary system is the largest organ system in the body, It alone accounts for about 16 percent of the total body weight of an individual. We will now look at the various functions of the integumentary system.
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Functions of the Integumentary System
Integumentary system functions vary from organ to organ and from tissue to tissue. We will look at each organ and describe the functions of each as well as why they are important:
Epidermis: Blood vessels are absent in the outermost layer, the epidermis. Squamous epithelial cells make up the majority of the epidermis. These cells include keratinocytes, melanocytes and even Langerhans cells. The epidermis is further subdivided into the corneum, lucidum, granulosum, spinosum and basale.
The various strata have their own functions as do the cells that make up the epidermis. These include protecting the body from foreign pathogens, waterproofing the body, skin pigmentation and fighting off foreign bodies as part of the immune system. They are also responsible for sensations of touch. The importance of the functions of the epidermis is quite obvious. Infections can cause a variety of diseases, so protection from foreign agents and pathogens is necessary.
Similarly waterproofing the body allows keeping liquids from penetrating the skin. Skin color or the pigment in the skin is important to protect us from ultraviolet radiation. Sensations of touch, part of the somatosensory system, are important to the survival of the individual.
Dermis: The dermis is the next layer beneath the epidermis. This layer contains many important glands. Sweat glands responsible for excretion of waste products and perspiration are located in this layer. Papillary ridges, located in the dermis, give us our unique fingerprints. Collagen fibers make up the connective tissue found in the dermis giving the skin elasticity. These functions are important to the survival of a human being.
Sweat glands help to get rid of waste and are responsible for cooling down the body, thus maintaining thermal regulation. Fingerprints provide a unique signature for a human being. Skin elasticity allows the skin to stretch, which is useful in many situations, and also gives the skin strength so as to avoid getting wrinkles which can make the skin appear to sag and unattractive.
Subcutaneous: The final layer of the skin is the subcutaneous. It is composed of adipose tissue. These provide cushioning of the organs that lie underneath the skin and also regulate the body temperature. These are essential functions as organs need to be protected for survival and body temperature needs to be regulated for the purpose of maintaining a stable internal environment for the functioning of the body.
2. Hair: As part of the integumentary system, hair comes in three different types in the human body. One is lanugo hair that covers the entire body of the fetus. Another is vellus hair which grows on most parts of the human body. Men have less vellus hair when compared to women and children.
Terminal hair is the third type of hair found in the axillary, male beard and pubic regions. Hair roots and hair bulbs are responsible for the extension of the hair to the surface. The hair shaft is the superficial layer of the dermis. The hair root is also found in the dermis. The hair follicle surrounds the hair root.
Hair is responsible for protection. Oil glands in the hair follicles keep the hair moist. Thermal regulation is also maintained to a certain extent by the hair. These functions are important as the vital organs need protection for survival and temperature regulation is required for a stable internal environment. The hair also plays a vital role in the appearance of a human being, thus helping in the process of selecting the best mate.
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3. Nails: Nails are composed of epidermal cells. Keratin is the main protein that makes up the structure of nails. Functionally, nails provide support in grasping objects. The sensitivity of the fingertip is also increased by the nails. These functions are important for the survival of a human being.
4. Glands and Nerves: There are various glands that are part of the integumentary system. One such gland is the sweat gland. Sweat glands come in two different types; eccrine glands and the apocrine glands. Eccrine glands are present on the palms, feet and forehead. Sweat coming from the eccrine glands is mostly composed of water. Their main function is thermal regulation. Apocrine glands also release sweat but are located in the armpits and pubic regions.
The main difference in sweat coming from the apocrine glands is that it is mostly composed of fatty acids. Their main function is to serve as scent glands. Sebaceous glands are another type of gland found in the skin. An oily substance is secreted by the sebaceous glands known as sebum. Sebum helps in protecting the skin and making it waterproof. It also keeps skin from becoming dry and cracked as well as inhibiting the growth of microorganisms.
Another gland that is part of the integumentary system is the ceruminous gland. These glands produce cerumen or earwax, which helps in the lubrication of the ear and in keeping it free from bacteria and fungi. Mammary glands are found in the breasts of women which secrete milk rich in antibodies and other nutrients for the newborn. A highly complex network of nerves exists within the integumentary system which sends and receives signals from the brain and is involved in the perception of sensation. All of these functions are very important for the survival of a human being.
Sweat glands are important as they help maintain body temperature essential for a normal human body. Sebaceous glands help protect the skin from damage, also an important function for survival. Ceruminous glands make certain that the ear is clean of dirt, which enables a human to hear clearly. Mammary glands are important as the newborn needs to be fed the mother's milk for a healthy developmental cycle.
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Other Important Functions of the Skin
In addition to the skin's functions described earlier, the skin also helps in the production of vitamin D, which is an important nutrient for the body. The skin aids in healing of minor cuts and burns by a process known as contact inhibition. This allows the skin to return to normal as the epidermis is sealed off by the skin.
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1. Student Reader: http://studentreader.com/integumentary-system-function/
2. Wiki Books: http://en.wikibooks.org/wiki/Human_Physiology/Integumentary_System
Image Credits:Wikimedia Commons/US-Gov