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Skin anatomy

Epidermis

Adapted from Wikipedia · Adventurer experience

Illustration showing the layers of human skin, helping to understand how our body protects us.

The epidermis is the outer layer of the skin, which also includes the dermis and hypodermis. It helps protect the body from infection and controls how much water leaves the body into the atmosphere.

The epidermis is made of many layers of flat cells. It grows from a base layer called the stratum basale, which has special columnar cells and stem cells. The epidermis can be thin or thick depending on the part of the body. It usually gets thinner as a person gets older. The epidermis is a type of tissue called a stratified squamous epithelium.

The word epidermis comes from Ancient Greek. Epi means 'over, upon' and derma means 'skin'. Anything related to the epidermis is called epidermal.

Structure

Schematic image showing a section of epidermis, with epidermal layers labeled

The epidermis is the outer layer of skin. It helps protect the body. It is made of different kinds of cells. The main cells are keratinocytes. There are also melanocytes, Langerhans cells, and Merkel cells. These cells work together to keep the body safe from harmful things and to help stop water from leaving the body.

The epidermis has several layers. The cells start at the bottom layer as basal cells. They move up through the layers, changing shape and what they do. When they reach the top layer, they become flat and filled with a special protein called keratin. This helps keep the skin strong and dry.

Function

The epidermis protects the body. It keeps out germs and helps guard against small injuries. Special layers and cells in the epidermis block unwanted materials and fight infections.

The epidermis also helps keep skin moist by controlling water loss. Our skin color comes from a substance called melanin, found in cells called melanocytes. These cells give skin its color and change with sun exposure. The epidermis has special touch-sensitive cells called Merkel cells, which help us feel when something touches our skin.

Clinical significance

For a comprehensive list, see List of cutaneous conditions.

Scientists can grow skin cells in a lab to make artificial skin. This helps them test new medicines safely before using them on people.

Sometimes, the top layer of skin can become thicker. This can happen in conditions like acanthosis, where the skin grows thicker. Another example is focal epithelial hyperplasia, which causes small, painless bumps inside the mouth. These changes are usually not serious and help doctors learn more about skin health.

Additional images

Epidermis and dermis of human skin

Cross-section of all skin layers

Illustration of epidermal layers

[Optical coherence tomography](/wiki/Optical_coherence_tomography) of fingertip

Images

A detailed diagram showing the layers and structure of human skin with clear labels.
A close-up microscopic view of the outer layer of human skin, called the stratum corneum.
A close-up microscopic view of the stratum granulosum layer of human skin, showing detailed cell structures.
A close-up microscopic view of skin layers, showing cells in the outer layer of the epidermis.
A close-up scientific image showing the base layer of human skin under a microscope.

This article is a child-friendly adaptation of the Wikipedia article on Epidermis, available under CC BY-SA 4.0.

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