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The skin is composed of three main layers. The deepest is the fatty subcutaneous layer that acts as a cushion against bumps and lumps and provides insulation.
Directly above it is the dermis, made of strong elastic fibers and collagen. This is where miles of blood vessels flow that expand and contract when environmental temperatures rise or fall. This also is where you find hair follicles, a network of nerves and substance-secreting glands. Sweat glands work overtime to cool us down when we overheat and can produce up to a liter of sweat a day. Sebaceous glands produce an oily, waxy substance called sebum that provides lubrication and waterproofing for the epidermis. It is what clogs pores in people with acne. It protects the epidermis, the uppermost layer exposed to the outside world.
The epidermis contains the tough horny layer of cells called the stratum corneum. Every five weeks or so, these flattened dead cells slough off and are replaced by new ones. Skin cells constantly fall off when we squirm around in our beds and rub against our clothes. Humans can shed up to nine pounds of skin every year. This natural turnover allows the fatty substance produced in the dermis to migrate freely to protect the surface layer. The epidermis is thicker on the soles of the feet and palms, and thinner on forearms and around the eyes.
The epidermis contains melanocytes responsible for producing melanin, the pigment that gives skin its color and absorbs energy from the sun. This is the layer that gets the most exposure to the elements and suffers the most abuse.
This content originally appeared on doctoroz.com
There are three fundamental layers of the skin:
- Subcutaneous fat layer
People speak about the many layers of the skin. But for practical purposes, the skin consists of just two layers. The top layer is the epidermis, the waterproofing layer. It keeps everything on the outside from entering the body and it keeps you from drying out. It contains fatty acids that are natural antibiotics, killing bacteria and preventing them from invading the body. It is also a barrier to viruses and fungi. The outer layer of the epidermis is made up of dead cells that mechanically protect the skin. This layer thickens in areas that are chronically irritated, such as the hands of a construction worker.
When the epidermis is broken, as in a scrape or a burn, liquid oozes out and quickly clots into a scab. This scab is a mechanical barrier that keeps the tissue from drying out. It also helps keep germs from getting into the body and causing infection. Epidermis contains the brown pigment melanin, a natural sun block. Melanin absorbs ultraviolet light and prevents it from injuring the DNA.
The lower layer of the skin is called the dermis. This is the structural layer, the leather of the skin. It holds you together. The dermis is made up mostly of collagen and about 4% elastin fibers. Collagen provides the strength of the skin, while elastin allows it to stretch and snap back.
Skin is composed of three layers: the epidermis (the outermost layer of skin -- about the thickness of a piece of paper), the dermis (the middle layer) and the subcutaneous layer (the deepest layer). The thickness of the dermis varies depending on the location. For example, eyelid dermis is quite thin, but back dermis is about half an inch thick.
The epidermis has three sub-layers: the stratum corneum, the squamous cell layer and the basal cell layer. It takes about one month for skin cells to move from the basal cell layer to the top of the stratum corneum and slough off.
The dermis is the middle layer of skin. It is a diverse combination of blood vessels, nerves, hair follicles and sebaceous (or oil) glands. The proteins collagen and elastin are found in the dermis. They provide support and elasticity to the skin. The sun's rays can break down these proteins and, eventually, the skin begins to wrinkle and sag.
The subcutaneous layer, or subcutis, is a layer of fatty tissue that provides nourishment to the dermis and upper layers of skin. It also conserves body heat and cushions internal organs against trauma. Blood vessels, nerves, sweat glands and deeper hair follicles extend from the dermis into the fat (hypodermis).
Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.