What Is the Epidermis?

Sweat glands in the epidermis allow sweat to evaporate from the surface of the body.
The epidermis forms the outer layer of skin, and is much thicker on the palms of the hands.
The epidermis creates a tough, renewable, waterproof barrier that protects human bodies against the environment.
The epidermis consists of multiple layers of epithelial cells.
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  • Written By: H. Colledge
  • Edited By: Heather Bailey
  • Last Modified Date: 20 September 2014
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The epidermis forms the outer layer of skin, creating a tough, renewable, waterproof barrier against the environment. It is a type of epithelium, the tissue that makes up surfaces and linings in the body. Over most of the body the epidermis is relatively thin, while on areas such as the palms of the hands and soles of the feet it is much thicker and hairless. Depending on its location, the epidermis may contain hair follicles, nails, and sweat and sebaceous glands. The study of skin is known as dermatology.

With its multiple layers of epithelial cells, the epidermis protects the body from the world outside. The main type of cell it contains is the keratinocyte, so called because it makes tough proteins called keratins which help to strengthen the skin. As well as being tough, the epidermis has to constantly renew itself and repair any damage resulting from injuries. It does so by continually growing new layers of cells.

The deepest layer of cells is known as the basal layer. Basal cells divide to form new keratinocytes and, as each successive layer forms, the layer above is pushed nearer to the surface of the skin. The closer cells are to the surface, the flatter they become, until the outermost layers are composed of what is called squamous epithelium. This is made from flat dead keratinocytes known as squames.

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While those cells at the surface are dead and constantly being shed, the layers of keratinocytes lower down are still alive and active. What is called the granular cell layer seals off the living cells, forming a waterproof barrier. This means that although water can cause the surface skin cells to swell when taking a bath, it may not penetrate the deeper epidermal layers. The presence of the granular cell layer also prevents unregulated loss of water from the body.

In addition to keratinocytes, there are a number of other cells in the epidermis. Melanocytes are partly responsible for the color of the skin, through their production of the pigment melanin. Merkel cells are associated with sensing light touch, and Langerhans cells form part of the body's immune response.

Sweat glands are present in the epidermis and are important in regulating the temperature of the body by allowing sweat to evaporate from its surface. Hair follicles and sebaceous glands occur together, with the glands producing oil that helps stop skin from drying out. Following an injury involving extensive removal of the epidermis, any epithelial cells that have been left behind in slightly deeper sweat glands and hair follicles may be used by the body to grow new skin.

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cranch
Post 6

I love this website. I'm taking human anatomy class, and sometimes I feel lost. This site is very helpful.

anon299917
Post 5

I used benzoyl peroxide for about 45 days every night, and my skin now has allover many wrinkles and I stopped the benzoyl peroxide now for about a month but my skin doesn't look young again. It's still very flaky and full of wrinkles. Did I damage my skin? will my skin renew itself again? How much time will it take?

sunnySkys
Post 4

@Azuza - Yeah, skin diseases can be very difficult to deal with. Like you said, they are clearly visible to anyone around you.

When I took psychology, we did a unit about health conditions, and we learned that people with serious skin diseases really suffer. People often stare at them quite rudely in public, and this can really affect their self-esteem!

Azuza
Post 3

@KaBoom - Good point. I know that the top layer of the epidermis is made up of dead cells. However, I assume (and hope) that some lotions and other skin care products do penetrate the epidermis to reach the lower layers. I'm going to look into this before I buy anymore skincare products though.

I took an anatomy class in school myself, and I remember being interested in the section about the skin. I was especially intrigued by all the different skin diseases that are out there. There are a lot! And they can be very difficult to deal with, because the skin is visible, unlike other organs in the body.

KaBoom
Post 2

When I took Anatomy and Physiology in college, I remember being completely amazed at the section on epidermis histology (histology is the study of tissues). I had no idea the skin had so many layers before I took that class!

Also, I was really amazed that the top layer of our skin is made up of dead cells! Most people slather products on top of their skin, but the cells are dead, so unless these products penetrate to the lower layers, what is the point?

You can do a lot more to keep your skin moisturized by keeping your body hydrating from within by drinking water, rather than putting chemicals all over your outer layer of skin!

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