1. The skin has two layers called the Epidermis and the Dermis. The Epidermis is a tough layer of skin which is the outermost layer of skin. Keratin gives this layer it toughness. The Epidermis is made up of five layers. The first is the stratum corneum. This is made from dead, mature skin cells called keratinocytes. These cells are constantly shed. The second layer is the stratum lucidum. This is found in thicker skin and helps reduce friction between the stratum corneum and the stratum granulosm. It is made of flattened skin cells. The next layer is the stratum granulosm. This is where keratin is formed. This layer produces materials and prevents evaporation, which keeps the skin waterproof. The following layer is the stratum spinosum. This contains the keratin making cells which are produced in the stratum basale. Finally the stratum basale is the last layer. This is the deepest layer. The cells in this layer continuously divide and form new keratinocytes to replace the cells which have been shed. Melanocytes are also present, this produces skin colouring. The dermis is the layer of skin which contains collagen and elastic fibres. This gives the skin strength. The nerves are present here. Together the epidermis and the dermis produce a cutneous layer (also known as the hypo-dermis). The hypo-dermis holds most of the bodies fat. Which means that because of this everyone’s skin varies in thickness. Creases over the joints are the same as the joint always folds in the same way. The integument includes the structures that grow out of the skin, and some glands. - Hair → Produced by keratin the hair has two layers. The inner layer is called the cortex. This gives the hair its colour. The hair grows out of follicles in the dermis. - Nails → These are keratin formed plates found on the end of the fingers and toes. Under each nail is a bed, which has a core connected to the nail. This ensures that the nail stays connected to the body. The core...
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