Anatomy- the Human Skin

Skin is the largest organ on the human body. It accounts for up to 20 percent of your the total body weight. Your skin renews itself every 14-28 days (the renewal slows as you get older). There are three major components of skin: hypodermis, dermis, and epidermis. The hypodermis is the deepest section of the skin. This is the fat that insulates the body from temperatures and absorbs shock. The hypodermis stores nutrients and energy and is the thickest layer. The dermis is the mid layers of skin. It is a fibrous collection of tissue that is interwoven and provides structure and support to the skin. This layer is about 2 mm thick. This section of the skin is composed of structural proteins, all of your blood and lymph vessels. The epidermis is the outermost layer of the skin. Categorized into five layers, the epidermis consists of 50 cell layers to 100 cell layers. The average epidermis thickness is 0.1 millimeters. The epidermis is the protective shield for the body. The deepest layer of your edpidermis is the stratum basale. It is a single layer of cubed cells. Keratinocytes (new skin cells) are formed in this layer through cell division to replace those shed continuously from the upper layers of the epidermis. The second layer of the epidermis is the stratum spinosum. This layer is composed of polygonal (many sided) keratinocytes. The third layer is called the stratum granulosum, is composed of 3-5 layers of flattened keratin. Cells in this layer are too far from the dermis to receive nutrients so they begin to die. The fourth layer in the epidermis is called the stratum lucidum (this layer is clear). This layer exists only in the fingertips, palms, and soles of the feet; It is 3-5 layers of flat cells. The fifth layer is called the stratum corneum. The outermost layer of the epidermis and is 25-30 layers of flat, dead keratinocytes. This is what makes your skin tough enough for protetion. Friction from the outside would causes this layer to naturally shed....