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Skin (human anatomy)

What is skin?

The skin is the largest organ of the body, with a total area of about 2 square metres. The skin protects us from microbes and the elements, helps regulate body temperature and permits the sensations of touch, heat and cold.

Anatomical Structures of Human Skin

Parts of the skin

Skin has 3 layers:

  • Epidermis - The epidermis, the outermost layer of skin, provides a waterproof barrier and creates our skin tone.
  • Dermis - The dermis, beneath the epidermis, contains tough connective tissue, hair follicles and sweat glands.
  • Hypodermis - The deeper subcutaneous tissue (hypodermis) is made of fat and connective tissue.

Other components of the skin include:

  • Blood vessels - To help keep your body a constant temperature, blood vessels in the skin dilate in response to heat or constrict in response to cold.
  • Sebaceous glands - The sebaceous glands secrete sebum, an oily substance that helps keep skin from drying out. Most of the glands are located in the base of hair follicles. Acne starts when the tiny hair follicles become plugged with these oily secretions.
  • Sweat glands - When your body gets hot or is under stress, these glands produce sweat, which evaporates to cool you. Sweat glands are located all over the body but are especially abundant in your palms, soles, forehead, and underarms.
  • Hair follicle - Every hair on your body grows from a live follicle with roots in the fatty layer called subcutaneous tissue.
  • Collagen - Collagen is the most abundant protein in the skin, making up 75% of your skin. This is also your fountain of youth as it's responsible for warding off wrinkles and fine lines. Over time, environmental factors and ageing diminish your body's ability to produce collagen.
  • Elastin - When you hear the word elastin, think elastic. This protein is found with collagen in the dermis and is responsible for giving structure to your skin and organs. As with collagen, elastin is affected by time and the elements. Diminished levels of this protein cause your skin to wrinkle and sag.
  • Keratin - Keratin is the strongest protein in your skin. It's also dominant in your hair and nails. Keratin is what forms the rigidity of your skin.
  • Colour - The skin’s colour is created by special cells called melanocytes, which produce the pigment melanin. Melanocytes are located in the epidermis.
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