Download The Skin - PITA- early career Wiki

The Skin Info Sheet:
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Skin is one of the largest organs of the body, making up 6-8% of the total body
weight. Probably the most important function of skin is to protect the body from
physical damage and bacterial invasion. It also helps control of body’s temperature.
The skin has an array of sense organs which sense the external environment, and has
cells which can make vitamin D in sunlight.
Diagram: Cross section through the skin
http://en.wikibooks.org/wiki/Anatomy_and_Physiology_of_Animals/The_Skin
The skin consists of two layers. The bottom layer is called the dermis and is under the epidermis
(see diagram).
The epidermis is the layer that bubbles up when we have a blister, it has no blood or nerves in it.
The cells at the base of the epidermis constantly divide and push the cells above them upwards. As
these cells move up they die and become the dry flaky scales that fall off the skin surface.
The cells in the epidermis die because a special protein called keratin is deposited in them. Keratin
is an extremely important substance for it makes the skin waterproof. Without it land vertebrates like
reptiles, birds and mammals would be like frogs and would only be able to survive only in damp
places.
The dermis contains the blood capillaries, hair follicles sweat glands, fat and nerves. The epidermis
reduces heat loss by causing ‘goose bumps’ closing the blood flow. It increases heat loss by
sweating and increasing blood flow.
The Body http://www.wikieducator.org/Skin_Worksheet
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