Download - The Skin
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The Skin
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• Skin is the largest organ of the body.• It is part of the integumentary system. • The integumentary system is made up of all of
the external coverings of the body, including the skin, nails, and hair.
• Like your bones and muscles, skin has many different functions in your body.
the skin
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Protection• Skin covers your bones and muscles, protecting
them from the outside environment. • Skin keeps your body from drying out in sunlight
and wind. • Skin also protects the cells and tissues under the
skin from damage. • Skin keeps dirt, bacteria, viruses, and other
substances from entering your body.
functions of the skin
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Sensory Response• Your skin has sensory receptors
that detect texture. • Sensory receptors in the skin
also detect temperature and sense pain. • The more sensory receptors there are in an area
of skin, the more sensitive the skin is.
functions of the skin
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Temperature Regulation• Skin helps control body temperature. • Skin has tiny holes, or pores, on
its outer surface. • When you exercise, sweat comes
from these pores. Sweating is one way that skin maintains normal body temperature.
• As sweat evaporates, excess thermal energy leaves the body and the skin cools.
functions of the skin
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Temperature Regulation• Another way the skin maintains body
temperature is by releasing thermal energy from blood vessels.
• When your body temperature begins to increase, such as when you are exercising, blood vessels near the skin’s surface dilate, or enlarge.
• This increases the surface area of the blood vessels and releases more thermal energy.
functions of the skin
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Temperature Regulationfunctions of the skin
blood vessels dilate to release heat
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Production of Vitamin D• If your skin is exposed to sunlight, it can make
vitamin D.• Your body needs vitamin D to help it absorb
calcium and phosphorus. • Vitamin D also helps bones grow.
functions of the skin
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Elimination• Normal cellular processes produce waste
products. • The skin helps eliminate, or get rid of,
some of these wastes.• Water, salts, and other waste products are
removed through the pores of the skin. • Elimination occurs all the time, but you probably
only notice it when you sweat.
functions of the skin
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• The skin that you see and feel on your body is the outermost layer of your skin. Below it are two other layers of skin.
• Each layer has a different structure and function.
structure of the skin
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structure of the skin
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Epidermisstructure of the skin
• The epidermis is the outermost layer of skin and the only layer in direct contact with the outside environment.
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Epidermisstructure of the skin
• The epidermis is thin but tough. The epidermis on your eyelids is thinner than a sheet of paper.
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Epidermisstructure of the skin
• Cells of the epidermis are constantly shed, or gotten rid of, and replaced by new cells
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Epidermisstructure of the skin
• One important function of the epidermis is the production of melanin.
• Melanin is a pigment that protects the body by absorbing some of the Sun’s damaging ultraviolet rays.
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Dermisstructure of the skin
• Below the epidermis is the dermis.• The dermis is a thick layer of tissue that gives
skin strength, nourishment, and flexibility.
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Dermisstructure of the skin
• The dermis contains sweat glands, blood vessels, nerves, hair follicles, and muscles.
• When the muscles in the dermis contract, you get goose bumps.
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Fatty Layerstructure of the skin
• The innermost layer of skin is sometimes called the fatty layer.
• It insulates the body, keeping it warm.
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skin injuries and repair
• Skin is often injured because it is exposed to the outside environment. You might have injured your skin by falling down or bruising it.
• Your body has different ways to repair skin. The type of repair depends on the type of injury and how serious it is.
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skin injuries and repair
• A bruise is an injury where blood vessels in the skin are broken, but the skin is not cut or opened.
• The broken blood vessels release blood into the surrounding tissue, forming the bruise.
• Bruises usually change color as they heal. This change in color is due to chemical changes in the blood under the skin’s surface.
Bruises
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skin injuries and repair
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skin injuries and repair
• When you break one or more layers of skin, a cut results.
• Cuts often cut blood vessels, too. • Blood that flows from a cut usually thickens and
forms a scab over the cut. • The scab helps keep dirt and other substances
from entering the body.
Cuts
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skin injuries and repair
• Skin heals by making new skin cells that repair the cut.
• Some cuts are too large to heal naturally. • If that happens, stitches might be needed to
close the cut while it heals.
Cuts
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skin injuries and repair
• A burn is an injury to your skin or tissues that can be caused by touching hot objects.
• Touching extremely cold objects, chemicals, electricity, radiation (such as sunlight), or friction (rubbing) can also cause burns.
• There are three degrees, or levels, of burns.
Burns
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skin injuries and repair
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skin injuries and repair
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skin injuries and repair
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healthy skin
• Another way to keep your skin healthy is to eat a balanced diet.
• You can also use gentle soaps to clean your skin and lotion to keep your skin moist.
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the skin and homeostasis
• You have read that the skin can make vitamin D and that it protects the body from outside substances.
• Both of these functions help regulate the body’s internal environment.
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the skin and homeostasis
• The skin also works with other body systems to maintain homeostasis.
• The skin and circulatory system help cool the body when it becomes overheated.
• The skin also works with the nervous system and muscular system to help the body react to stimuli.
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the skin and homeostasis