Skin and the Integumentary System

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Skin and the Integumentary System

• Chapter 6

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Skin is

• is the largest heaviest organ in the body.
• covered in hair.
• vital in maintaining homeostasis.
• a protective barrier.
• a.k.a. the cutaneous membrane.

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Skin is

• part of the integumentary system.
• divided into three distinct layers
• EPIDERMIS outer layer
• DERMIS middle layer
• SUBCUTANEOUS bottom layer
• (Not a true skin layer )

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EPIDERMIS

• Stratified squamous epithelium
• Old cells die are pushed up
• Cytoplasm hardens, fills with keratin
• KERITINIZATION
• Forms tough, waterproof layer
• - STRATUM CORNEUM

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EPIDERMAL LAYERS

• Stratum corneum
• Stratum lucidum
• Only in thick skin
• Stratum granulosum
• Stratum spinosum
• Stratum basale

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MICROSCOPIC EPIDERMIS
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EPIDERMAL PROTECTION

• Stratum basale contains MELANOCYTES
• Produce MELANIN
• Dark pigment in granules that absorbs UV
  radiation
• Granules spread to nearby cells

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SKIN COLOR
Light Skin

• Everyone has the same of melanocytes
• Skin color depends on amount of melanin produced
• Other factors
• Blood supply
• Beta carotene
• Bilirubin

Dark Skin
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THE KING OF POP

• Whats up with M.J.s skin?
• Vitiligo disorder in which the skins
  melanocytes are destroyed

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VITLIGO

• Possible causes
• Body is allergic to its own melanocytes
• Cells destroy themselves during pigment creation
• FYI Cancer patients can develop vitiligo after
  treatment the weird thing?
• The vitiligo actually seems to stop the spread of
  the disease!

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BACK TO M.J.

• Underwent repigmentation
• Turn white patches dark again.
• Process failed
• Went through depigmentation to reverse it
• Monobenzene is used to bleach the skin until its
  all the same color
• If he stopped the treatments, he would turn back

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ALBINISM

• Body is unable to produce or distribute melanin
  due to possible genetic defects
• High risk of skin cancer and eye problems

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PSORIASIS

• Excessive growth and reproduction of
  keratinocytes followed by inflammation
• Caused by the immune system mistakenly reacting
• Speeds up creation of new cells and slows loss

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WHAT ARE THOSE WHITE SPOTS ON MY FINGERNAILS?

• Leukonychia
• Can be caused by trauma
• Not a calcium deficiency
• Zinc deficiency is more pronounced

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HOW THICK IS YOUR SKIN?

• Epidermis
• .5 mm on eyelids
• Up to 1.5 mm on palms/soles
• Dermis
• .3mm on eyelids
• 3 mm on upper back

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DERMIS

• Directly below epidermis
• Dermal papillae project upwards into epidermis
• Produce fingerprints
• Made mostly of dense connective tissue

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DERMAL STRUCTURES
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BEDSORES

• Interference with blood flow to the dermis can
  kill epidermal cells
• Lying in one position too long causes weight of
  body to block skins blood supply
• A.k.a. PRESSURE ULCER
• Treatment includes shifting the patient
  frequently and keeping the wound clean

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SUBCUTANEOUS LAYER

• A.k.a. HYPODERMIS
• Loose connective and adipose tissue
• Insulation
• Major blood supply

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SEVERITY OF BURNS
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INJECTIONS

• SUBCUTANEOUS INJECTION
• Flu shot, penicillin
• INTRADERMAL
• TB test
• INTRAMUSCULAR
• Epinephrine injection

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ACCESSORY ORGANS OF THE SKIN

• NAILS
• HAIR FOLLICLES
• SEBACEOUS GLANDS
• SUDORIFEROUS GLANDS

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NAILS

• Protective coverings
• NAIL ROOT LUNULA contain actively dividing
  cells
• Cells die and become keratinized forming nail body

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HAIR FOLLICLES

• Hair development
• Specialized epidermal tissue
• Nourished by dermal blood supply
• Cells divide near base and become keratinized

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HAIR FOLLICLES

• Hair color is determined by melanocytes near root
• More melanin produced, darker hair
• ARRECTOR PILI- smooth muscles that control goose
  bumps

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SEBACEOUS GLAND

• Specialized epithelial gland that produces SEBUM
• Oily mixture that keeps hair and skin soft,
  pliable and waterproof
• Attached to follicles

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SUDORIFEROUS (SWEAT) GLANDS

• Tiny tube that is attached to a coil in dermis
• ECCRINE GLANDS respond to temperature
• Sweat comes out of PORE
• Forehead, neck, back

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SUDOIFEROUS (SWEAT) GLANDS

• APOCRINE GLANDS
• Respond to emotions
• Active at puberty
• Groin, axillary regions

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SKIN SENSORY RECEPTORS

• The skin has receptors for touch
• Heat
• Pressure
• Pain
• Cold

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SKIN TOUCH RECEPTORS

• MERKELS DISCS
• Sensitive to vibration movement
• Found in stratum basale
• ROOT HAIR PLEXUS
• Sensitive to hair movement

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SKIN PRESSURE RECEPTORS

• MEISSNERS CORPUSCLES
• Light touch objects that brush the skin
• Dermis
• PACINIAN CORPUSCLES
• Heavy pressure
• Dermis/Subcutaneous layer

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OTHER SKIN RECEPTORS

• THERMORECEPTORS
• KRAUSE CORPUSCLES
• Cold
• RUFFINI CORPUSCLES
• Heat
• PAIN RECEPTORS
• Free nerve endings

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Hyperhidrosis

• Overactive sweat glands
• Hands
• Feet
• Armpits
• Caused by overactive nervous system
• Treatment
• Antiperspirant
• Iontophoresis
• Botox injections

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The Skins Role in Homeostasis

• Vital in maintaining proper body temperature
• Important in the healing of wounds
• Aids in production of Vitamin D

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VITAMIN D PRODUCTION

• Skin cells help produce vitamin D
• Dehydrocholesterol made by cells in digestive
  system
• Reaches skin and is changed to vitamin D when
  exposed to UV light

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Regulation of Body Temp

• During intense heat, nerve impulses signals the
  body to release heat
• Blood vessels dilate, giving off heat through
  skin
• Eccrine sweat glands become active
• Sweat evaporates cooling skin

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Regulation of Body Temp

• If too much heat is lost
• Muscles in dermal wall contract
• Decreases blood flow and heat loss
• Sweat glands inactive
• Skeletal muscles contract involuntarily
• Release heat
• Shivering

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Healing of Wounds

• INFLAMMATION wound and surrounding areas become
  swelled
• Response to injury stress
• 4 signs of inflammation
• Redness
• Warmth
• Swelling
• Pain

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Inflammation

• Redness - caused by increased vasodilatation
• More blood in area
• Heat increased metabolism WBCs try to destroy
  invaders

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Inflammation

• Swelling Fluid in area due to change in osmotic
  pressure
• Abnormal build up of fluid called EDEMA
• Pain Pressure on nerve endings from fluid

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Healing of Wounds

• Shallow wounds (epidermis)
• Epithelial cells divide and fill in gap

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Healing of Wounds

• Deep wounds (dermis or subcutaneous layer)
• Blood vessels broken
• Clot forms and dries into a scab
• Fibroblasts lay down collagen fibers forming scar
• Phagocytes remove foreign particles