How Your Skin Works

Did you know that the skin is the largest organ in the human body? It makes up approximately one-seventh of our body weight.


Did you know that the skin is the largest organ in the human body? Organs are groups of tissues with a unique purpose. We get the word organ from the Latin word "organum," which means instrument or tool, and that's precisely what organs are. They are specialized tools that perform vital functions. What does skin play in the human body?

Some Key Facts About Skin

Before we dive into what skin does and how it works, it's essential to put into perspective how amazing this organ really is. While we rely on skin to shield us from the harsh environments we live in, it's only a few millimeters thick, even at its thickest point. But despite being thin, the sheer amount of it we have means that it's also our largest and heaviest organ. For example, your skin makes up approximately one-seventh of your body weight and can reach a surface area of 1.5 to 2 square meters, depending on your size (roughly the size of a twin bed).

The Different Layers of Skin

The skin comprises three layers of tissue:

  • Epidermis - This is the outer layer of the skin and is made up mainly of keratinocytes (cells that produce the protein keratin). Around 90% of the epidermal skin is this type of cell. The epidermis itself also has layers. Most areas of the body have four layers, while thicker areas of skin, like the palms of the hands and the soles of the feet, have five layers.

  • Dermis - This is the inner or middle layer of skin and is much thicker than the epidermis. The dermis comprises many cells, including collagen, elastin, blood vessels, sweat glands, nerves, and specialized cells like mast cells and fibroblasts.

  • Hypodermis - This is the bottom and fatty (subcutaneous) layer of the skin. It provides structural support.

The Function of Skin

All organs have specialized functions within the human body, and skin is no different. The skin has a lot of different functions, with each layer having its own specialized functions.

The Function of the Epidermis

  • The primary function of the epidermis is to act as a protective barrier, keeping germs and pathogens from entering your bloodstream and causing infections. It also protects your body from UV damage from the sun and shields your body from rain and wind.

  • The epidermis contains Langerhans cells that play a vital role in your immune system by helping fight pathogens.

  • It also contains melanin, the substance that determines your skin color.

The Function of the Dermis

  • The Dermis contains collagen and elastin, vital components that make skin cells strong, resilient, and flexible (as opposed to brittle). Collagen and elastin also help your skin return to its original shape (or as close to) after being stretched.

  • Hair growth starts here with follicles embedded in the dermis.

  • Nerve receptors in the dermis tell you a lot about your environment, including how hot or cold something is and whether it's causing you damage (pain).

  • The dermis also contains oil glands that produce oil to protect your skin from water.

  • The dermis contains blood vessels that provide the skin system with nutrients.

  • The sweat glands in the dermis help regulate your body temperature.

The Function of the Hypodermis

  • The fat contained in the hypodermis helps cushion your muscles and bones, protecting them from injuries when you fall or experience other physical trauma.

  • Hypodermis contains connective tissue that attaches skin to your muscles and bones.

  • The fat helps regulate your body temperature, ensuring your internal organs don't get too hot or cold.

Why Study Skin?

Continual scientific study into the skin and how it works is crucial to help treat skin conditions like acne, atopic dermatitis, psoriasis, rosacea, skin cancer, and even hair loss. Skin conditions are the fourth most common cause of human illness.