The Skin

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The Skin

• Ch. 17 s.3

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Your skin is the largest organ of your body.

• It is the major part of the Integumentary system

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Integumentary system

• Forms the external body covering
• Composed of skin, sweat glands, oil glands, hair,
  and nails
• Protects deep tissues from injury and synthesizes
  vitamin D

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Interesting Facts

• 21 Square Feet
• 4 Kilograms/9 pounds, 7 - 15 of Total Body
  Weight
• Complex Combination of Tissues
• Continuous Layer

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One Square Inch Contains

• 20 Blood Vessels
• 65 Hairs Hair Muscles
• 78 Nerves
• 78 Sensors for Heat
• 13 Sensors for Cold
• 160 Sensors for Pressure

• 100 Sebaceous/Oil Glands
• 1300 Nerve Endings
• 19,500,000 Cells
• 0.5 Million Cells Dying Being Replaced

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Skin is made up of three layers of tissue
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• 1. Epidermisthe outer, thinnest layer
• a. The outermost cells of your skin are dead and
  rub off when you touch anything.
• b. New cells are constantly produced at the base
  of the epidermis.
• c. Cells produce melanin, which is a pigment
  that protects your skin and gives it color.
• 2. Dermisthe middle layer
• a. The dermis is thicker than the epidermis.
• b. The dermis contains blood vessels, nerves,
  muscles, oil, sweat glands, and other structures.
• 3. Fatty layer insulates the body

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Skin has many functions.

• 1. Protectionforms a protective covering over
  the body that prevents injury
• a. Many disease-causing organisms cannot pass
  through the skin.
• b. Prevents excess water loss
• 2. Sensory responsenerve cells in the skin
  detect and relay information to the brain
• 3. Formation of vitamin D, which helps your body
  absorb calcium
• 4. Regulation of body temperature
• a. Blood vessels in the skin help release or
  hold heat.
• b. Perspiration from the sweat glands eliminates
  excess heat that has been produced by muscle
  contractions.
• 5. Elimination of wastes through sweat glands

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When injured, the skin produces new cells and
repairs tears.

• 1. Bruises happen when tiny blood vessels beneath
  the skin burst and leak into surrounding tissues.
• 2. When you have a cut, a scab forms to prevent
  bacteria from entering your body.
• a. Cells in the surrounding blood vessels fight
  infection.
• b. Skin cells beneath the scab grow to fill in
  the gap of the torn skin.
• 3. Doctors are able to repair severe skin damage.
• a. Skin grafts are pieces of skin that are cut
  from one part of a persons own body and moved to
  the injured area.
• b. Doctors sometimes use skin from cadavers to
  prevent infections until a victims skin heals.
• c. Doctors are beginning to grow large sheets of
  epidermis from small pieces of the victims
  healthy skin.

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Burns
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DISCUSSION QUESTION

• What are the dangers to your body when your skin
  is damaged?
• Bacteria and other disease-causing organisms
  could enter your body. The body could lose too
  much water or blood.

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Example Julies crash
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Skin Color?

• Just different shades of one color melanin
• Dark enough to protect against radiation, but
  light enough to produce Vitamin D
• Specific climate areas an important factor
• Interbreeding within own people group continues
  specific traits
• The term race is an evolutionary termthere is
  really only one race the Human Race

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DC Talk Colored People

• Pardon me, your epidermis is showing, sirI
  couldn't help but note your shade of melaninI
  tip my hat to the colorful arrangementCause I
  see the beauty in the tones of our skinWe've
  gotta come togetherAnd thank the maker of us
  all(chorus)A piece of canvas is only the
  beginning forIt takes on character with every
  loving strokeThis thing of beauty is the passion
  of an artists heartBy Gods design, we are a
  skin kaleidoscopeWe've gotta come
  together,Aren't we all human after all?
  (repeat chorus)Ignorance has wronged some
  racesAnd vengeance is the lordsIf we aspire to
  share this spaceRepentance is the cureWell,
  just a day in the shoes of a color blind
  manShould make it easy for you to seeThat these
  diverse tones do more than cover our bonesAs a
  part of our anatomy(repeat chorus)Were
  colored people, and they call us the human
  raceoh, colored peopleWere colored people,
  and we all gotta share this spaceyeah we've got
  to come together somehowWere colored people,
  and we live in a tainted worldred and yellow,
  black and whiteWere colored people, every man,
  woman, boy, and girlcolored people, colored
  people, colored people, colored people, yeah

(chorus)Were colored people, and we live in a
tainted placeWere colored people, and they call
us the human raceWeve got a history so full of
mistakesAnd we are colored people who depend on
a holy grace
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Activity

• Use a lens to observe your skin