Transcript Lecture 5.2: Integumentary System

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UV rays cause cholesterol-like steroid to
change to vitamin D3
Decreased Vitamin D leads to abnormal bone
growth
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Most common cancer
Most people survive
Treatment = removal of tumor
Melanomas—extremely dangerous
Usually begin as mole
Grow rapidly
Spread via lymphatic system
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Papillary Layer
Supports and nourishes epidermis
Capillaries and nerves for skin surface are
here
Reticular Layer
Elastic fibers for elasticity
Collagen fibers limit elasticity for protection
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Hair Follicles
Sweat Glands
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Increased adipose cells
Decreased heat loss in infants
Energy reserve
Shock absorber
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Everywhere except:
Sides and soles of feet
Palms
Sides of fingers/toes
Lips
Parts of genitalia
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Hair follicles—where hair is produced
Hair papillae—where vessels and nerves are
Hair root—anchors hair into skin
Hair shaft—what we see
Cuticle—surface layer of hair
Grows about 0.3 mm/day
May become inactive for awhile
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Round hairs = straight hair
Flattened hairs = curly hair
Functions
Protect from UV rays
Cushion light blows
Insulate
Prevent entry of pathogens
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Sensory nerve fiber at base
Arrector pili—bundle of smooth muscle
Causes hair to stand up
“Goosebumps”
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Due to amounts of pigment produced by
melanocytes
Due to genetics
Pigment production decreases with age
No pigment = white hair
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Average about 50 hairs/day
More than 100 hairs/day = hair loss
Temporarily due to:
Drugs
Diet
Radiation
High Fever
Stress
Pregnancy
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AKA: Oil Glands
Secrete into hair follicle
Sometimes onto skin
Secreted through arrector pili
Sebum—secretion of oil
Lubricates hair and skin
Inhibits bacteria
High amounts at puberty
Acne—sebaceous duct blocked
Secretions accumulate
Causes pimples
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Apocrine Glands
Secrete into armpits, nipples and groin
Sticky, cloudy, odorous secretion
Starts at puberty
Odorous when bacteria feed on sweat