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Our Skeletal System and the Skin

Types of Bones; Fracture

Skin is the outermost covering of the body and covers the entire body.

It has a surface area of 1.5-2 meters and accounts for 12-15% of the total body weight.

The skin along its derivatives constitutes the integumentary system.

Structure of the Skin

Skin is made up of two main components:

  • Skin proper

  • Skin derivatives

Skin Proper

The skin proper is composed of two layers:

  • Epidermis

  • Dermis

Epidermis

The epidermis is the outer layer of the skin, which is formed by stratified squamous epithelium layers, which are arranged in horizontal layers. It is considered to be a lifeless tissue as it lacks any blood vessels.

The epidermis contains keratin, which makes it tough. The epidermis is made up of three sub-layers, which are:

  • Outermost cornified layer (stratum corneum) - This layer is made up of dead cells containing keratin. This layer forms a tough outer covering. The cells in these layers get worn out and are continuously replaced. This layer provides resistance against mechanical damage, bacterial infection and loss of water by evaporation.

  • Granular layer- It consists of flattened living cells and replaces the cornified layer when its cells get worn out.

  • Malpighian layer − It is the innermost layer of the epidermis. Cells in this layer are continuously dividing. This layer contains the pigment melanin, which determines the skin color.

Dermis

It lies below the epidermis and is thicker than the epidermis. The dermis has two main layers − the papillary layer consisting of dermal papillae and the reticulate layer. This layer consists of elastic connective tissue, blood vessels, sweat glands, oil glands, and hair follicles. The dermis also has specialized cells called fibroblasts, which help in the production of collagen and elastin fibres.

Functions of the Skin

The most important functions of the skin are:

  • Protection − The skin provides protection to the body from mechanical injury, ultraviolet rays, from disease-causing microbes, and prevents desiccation.

  • Temperature regulation − The skin helps in the maintenance of body temperature at a constant.

  • The skin contains numerous sense receptors, which help in perceiving the surroundings.

  • The skin is also involved in the synthesis of vitamins such as Vitamin D.

  • The skin also helps in disposing of the excess water and salt by evaporation.


Can you tell the main determinant of the human skin colour? 

Melanin 
is the pigment produced by certain glands in the skin. The amount of melanin present in the cells of the epidermis decides the skin colour. It is an effective absorbent of light and protects the skin from the UV rays. The more the melanin present in the skin, the darker will be the colour of the skin.
There are some abnormalities related to skin …

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