Organ of special sense (SKIN).

SKIN-

The skin completely covers the body and it's contenders with the membrane living the body artifice its.

• Protect the underlying structure from jury.
• Contains sensor (somatic)nerve ending of pain temperature and touch.
• It involves in the regulation of body temperature.

• STRUCTURE OF SKIN-The skin is the largest organ in body and has a surface area about 1.5 to 2 mm in a about it contain glands hair and nails. There are two main layer.

1. Epidermis- The epidermis is most superficial composed of stratified keratinized  squamous epithelium. It thickest on the palm of the hand scales of the feet. There are no blood vessels or nerve ending the epidermis.
2. DERMIS- The dermis is touch and elastic. It formal from connective tissue and the moirés  contains collagen fiber inters based with elastic fibers  rupture of elastic fibers occurs when the skin is over stretched resulting in permanent striae or stretch marks that may be found in pregnancy for obesity the structure in the dermis are -

• Blood vessels.
• Lymph vessels.
• Sensory.

Sweet glands and their duct hair arrector pili muscle.

1. Blood vessels - Arterioles from a fine network with capillaries branches supply. It obtain nutrients and oxygen from intersected fluid drive from blood vessels in the papillae of dermis.
2. Lymph vessels-These form a network though out the dermis.
3. Sensory nerve ending-Sensory receptors sensitive to touch temperature,
5. The skin with its appendages (hair and nails) is commonly referred to as integumentary system. The skin is an organ with highly specialized functions that are essential for human survival. The surface area of the skin makes it one of the largest organs in the body, covering approximately 20 square feet or 3000 square inches in an average-sized adult. 
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7. The skin is structurally composed of two layers, the outer layer is the epidermis and the inner layer the dermis. Under the dermis lies the subcutaneous tissue, also known as the hypodermis. Three kinds of glands areassociated with the skin. They are the sebaceous glands, sudoriferous or sweat gland and ceruminous gland.
9. 254 Functions of the Skin 
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11. Skin ts the body's first line of defence. Normally, the Skin hosts large number of resident bacteria, which on intact sk; prevent excess growth of fungi. Sebum secreted by the Sebaceous glands has antibacterial and antifungal Properties Normal skin acidity also inhibit growth of pathogenic organisms 
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13. The skin assists in regulating body temperature. The Skin helps to screen out harmful ultraviolet rays from the sun, by it also lets in necessary UV rays that converts 7-dehydrochole, Sterol into vitamin D for normal growth of bones and teeth, 
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15. The skin is an important sensory organ containing sensory receptors that respond to heat, cold, touch, pressure and pain, The nerve endings on the skin also helps to maintain homeostasis. 
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17. Melanocytes which afte located at the base of the epidermis produce melanin, a pigment responsible for skin colour. Other epidermal cells-Langerhans’ cells and Granstein cells interact with T cells to assist in the immune process.