What is skin?

Skin is the largest organ on our body, made up of several different parts, including water, protein, lipids (fats), and different minerals and chemicals. Throughout your life, your skin will change, for better or worse. In fact, your skin regenerates itself approximately every 27 days. It’s very important to treat your skin properly to maintain the health and vitality of this crucial organ.

This information serves as an overview only, and should not replace a professional’s advice.

What does your skin demand every day?

During the hustle and bustle of your daily routines, it’s easy to skip that glass of water or to skip cleaning. Over time, though, those bad habits can take a toll on your skin. Each day, you should be sure to provide your skin with:

  • Plenty of water.
  • Thorough cleansing, twice a day. At night, make sure you remove all your make-up and cleanse properly before going to bed.
  • Balanced nutrition.
  • Moisturizing. This is a necessary step even for those who have oily skin. There are plenty of moisturizers on the market that are oil-free.
  • Sun protection, sun protection, sun protection. It is absolutely crucial to protect your skin from harmful UVA and UVB light rays. Sunscreen (SPF 30 or higher) is recommended every day. This will help prevent sun damage, skin cancers, and wrinkles.

Over the course of your life, you should pay attention to all parts of your skin. Familiarize yourself with it so that you’ll notice any changes that might occur, such as different moles or patches that might need further attention.

What is the skin’s structure?

Epidermis: The outer layer

The epidermis is the thinnest layer, but it’s responsible for protecting you from the harsh environment, with 5 layers of its own. The epidermis also hosts different types of cells:

  • Keratinocytes, which produce the protein known as keratin, the main component of the epidermis.
  • Melanocytes, which produce your skin pigment, known as melanin.
  • Langerhans cells, which prevent things from getting into your skin.

Dermis: The middle layer

The dermis is the layer that gives your skin its fullness and plumpness. Age and the sun can damage the dermis and lead to wrinkles.

The dermis is a complex combination of blood vessels, hair follicles, and sebaceous (oil) glands. Here, you’ll find collagen and elastin, 2 proteins necessary for skin health because they offer support and elasticity (your skin’s ability to go back to its original state after being stretched). Fibroblasts are the cells you’ll find in this layer, because they synthesize collagen and elastin. This layer also contains pain and touch receptors.

Hypodermis: The fatty layer

This layer is also known as the subcutis. It hosts sweat glands and fat and collagen cells, and is responsible for conserving your body’s heat and protecting your vital inner organs. Reduction of tissue in this layer contributes to sagging skin.

What are the skin’s proteins?

  • Collagen: Collagen is the most plentiful protein in the skin, making up 75-80% of your skin. Collagen and elastin are responsible for warding off wrinkles and fine lines. Over time, the environment and aging reduce your body’s ability to produce collagen.
  • Elastin: Think elastic. Elastin is found with collagen in the dermis. It’s another protein, responsible for giving structure to your skin and organs. As with collagen, elastin is affected by time and the elements. Lower levels of this protein cause your skin to wrinkle and sag.
  • Keratin: Keratin is the main protein in your skin, and makes up hair, nails, and the surface layer of the skin. Keratin is what forms the rigidity of your skin and helps with the barrier protection that your skin offers.

Last reviewed by a Cleveland Clinic medical professional on 03/17/2016.


  • Proksch E, Jensen J. Chapter 47. Skin as an Organ of Protection. In: Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, Dallas NA, eds. Fitzpatrick's Dermatology in General Medicine. 8th ed. New York: McGraw-Hill; 2012. Accessed 4/1/2016.++accessmedicine.mhmedical.com++ (http://accessmedicine.mhmedical.com/Content.aspx?bookId=392&sectionId=41138745)
  • . Accessed 4/1/2016American Academy of Dermatology (https://www.aad.org/public)
  • National Cancer Institute. Accessed 4/1/2016.++Layers of the skin++ (http://training.seer.cancer.gov/melanoma/anatomy/layers.html)

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