How The Skin Works Animation - Structure and Function of the Human Skin Video - Skin Layers Anatomy

Skin is the body's largest organ. About six pounds of skin cover eighteen square feet on an average adult.

The top layer of skin is called the epidermis. It protects the underlying skin layers from the outside environment and contains cells that make keratin, a substance that waterproofs and strengthens the skin. The epidermis also has cells that contain melanin, the dark pigment that gives skin its color. Other cells in the epidermis allow us to feel the sensation of touch and provide the body with immunity against foreign invaders like germs and bacteria.

The very bottom layer of the skin is the hypodermis. It contains the fat cells, or adipose tissue, that insulate the body and help it conserve heat. The layer between the epidermis and the hypodermis is the dermis. It contains the cells that give skin strength, support, and flexibility. As a person ages, the cells in the dermis lose their strength and flexibility, causing the skin to lose its youthful appearance.

Located in the dermis are sensory receptors. They allow the body to receive stimulation from the outside environment and experience pressure, pain, and temperature. Small blood vessels provide the skin with nutrients, and remove its waste products.

Sebaceous glands produce the oil in the skin, which keeps it from drying out. The oil from the sebaceous glands also helps to soften hair and kill bacteria that get in the skin’s pores. These oil glands are all over the body, except on the palms of the hands and the soles of the feet.

The layers of your skin

Your skin has a big job to do protecting your body, so it's made to be tough and stretchy. There is a lot more to this job than it might seem. There are three main layers of the skin.

Epidermis is the top layer of the skin, the part of the skin you see.
Dermis is the second layer of skin. It's much thicker and does a lot for your body.
Subcutaneous fat is the bottom layer.

Epidermis: Your skin's top layer, the epidermis, is super thin on some parts of your body (your eyelids) and thicker on others (the bottoms of your feet). The epidermis is the layer of skin in charge of:

Making new skin cells: This happens at the bottom of the epidermis. The skin cells travel up to the top layer and flake off, about a month after they form.
Giving skin its color: The epidermis makes melanin, which is what gives your skin its color What gives skin its color?
Protecting your body: The epidermis has special cells that are part of your immune system and help you stay healthy.

Dermis

A lot happens in the next layer, the dermis. The jobs of the dermis include:

Making sweat: There are little pockets called sweat glands in the dermis. They make sweat, which goes through little tubes and comes out of holes called pores. Sweating keeps you cool and helps you get rid of bad stuff your body doesn't need.
Helping you feel things: Nerve endings in the dermis help you feel things. They send signals to your brain, so you know how something feels if it hurts (meaning you should stop touching it), is itchy or feels nice when you touch it.
Growing hair: The dermis is where you'll find the root of each tiny little hair on your skin. Each root attaches to a tiny little muscle that tightens and gives you goose bumps when you are cold or are scared.
Making oil: Another type of little pocket, or gland, in your skin makes oil. The oil keeps your skin soft, smooth and waterproof. Sometimes the glands make too much oil and give you pimples. (See Acne: Pimples and Zits.
Bringing blood to your skin: Blood feeds your skin and takes away bad stuff through little tubes called blood vessels.

Subcutaneous fat

The bottom layer of skin is the subcutaneous fat layer. This layer plays an important role in your body by:

Attaching the dermis to your muscles and bones: This layer has a special connecting tissue that attaches the dermis to your muscles and bones.
Helping the blood vessels and nerve cells: Blood vessels and nerve cells that start in the dermis get bigger and go to the rest of your body from here.
Controlling your body temperature: The subcutaneous fat is the layer that helps keep your body from getting too warm or too cold.
Storing your fat: This fat pads your muscles and bones and protects them from bumps and falls.

The human skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system. The skin has multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to that of most other mammals. Though nearly all human skin is covered with hair follicles, it can appear hairless. There are two general types of skin, hairy and glabrous skin. The adjective cutaneous literally means "of the skin" (from Latin cutis, skin).