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The Basic Facts

The Basic Facts
Human Skin - The Basic Facts
- what is skin? (Latin - cutis)
- is your body's largest organ
- covers your entire body
- has a total surface area of about 1.5 - 2 m2 (depending on your body's size)
- makes up about 7% of your body's total weight
- weighs about 4 kg
- suffers the most wear and abuse of any part of the human body
- composition of your skin:
- two (2) distinct main layers: the EPIDERMIS and the DERMIS
- EPIDERMIS:
- nature of:
- the thinner of the two main skin layers
- made up of many cell layers
- has no blood vessels of its own
- the most inner cell layer provides cells for the outer cell layers, by having its cube-shaped cells divide quickly
- new cells push older cells toward the surface
- as epidermal cells move toward the surface, they become enriched in keratin (a fiberous protein - also found in hair and nails)
- upon reaching the surface, these cells have died and become flat
- at the surface, these dead cells "slough-off"
- Epidermis is replaced every few weeks
- in a lifetime the average person will shed about 18 kg of skin
- structure of (from surface inward):
- Stratum Corneum (outer most layer) - horny layer - accounts for up to 75% of the Epidermis' thickness
- Granular layer (stratum granulosum)
- Spinous layer (stratum spinosum)
- Basal layer
- nature of:
- DERMIS:
- nature of:
- the thicker of the two main skin layers
- is protected by the Epidermis
- made up of connective tissue - with elastin fibers (to keep it flexible and pliable) and collagen fibers (for strength and resilience)
- rich in blood vessels and nerve endings
- feeds the Epidermis with nutrients and oxygen
- contains the structures of the intergumentary system (hair follicles, oil and sweat glands)
- nature of:
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