CP PHYSIOLOGY: SKIN

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CP PHYSIOLOGYSKIN THE INTEGUMENTARY SYSTEM
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4 TYPES OF MEMBRANES?

• 1) serous membranes
• line body cavities that dont open to the outside
• location thorax, abdomen the organs within
• made of simple squamous epithelium loose
  areolar CT

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4 TYPES OF MEMBRANES?

• 2) mucous membranes
• line cavities tubes that open to the outside
• location oral nasal cavities, tubes of the
  digestive, respiratory, urinary, reproductive
  systems
• made of epithelium w/ goblet cells
  loose areolar CT
• secrete mucus

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4 TYPES OF MEMBRANES?

• 3) synovial membranes
• location the inner linings of synovial joint
  cavities
• made of dense CT loose areolar CT adipose
  tissue
• secrete synovial fluid to lubricate
  joints

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4 TYPES OF MEMBRANES?

• 4) cutaneous membranes
• skin

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INTRODUCTION?

• integumentary system skin accessory organs
• hyperhidrosis a condition of profuse,
  uncontrollable, unpredictable sweating

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SKIN ITS TISSUES?

• skin is a large organ vital to maintaining
  homeostasis

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Skin stats

• Surface area 1.2 to 2.2 square meters
• Weight 9 to 11 pounds
• Accounts for 7 of an adults total body weight
• 1.5 to 4 mm thick in various parts of the body
• Integument covering

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functions of skin

• Protection chemical, physical, biological
• regulates body temperature
• Insulation fat storage
• prevents water loss from deeper tissues

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functions of skin

• houses sensory receptors sensitive to pain,
  temperature, touch, pressure
• makes biochemicals such as vitamin D
• excretes some waste
• Blood reservoir has an extensive vascular supply

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2 layers of skin

• epidermis outer layer made of stratified
  squamous epithelium

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2 layers of skin

• dermis thicker inner layer made of connective
  epithelial tissue, smooth muscle, nervous tissue,
  blood

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2 layers of skin

• the 2 layers are separated by the basement
  membrane (areolar c.t.)

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• a subcutaneous layer (hypodermis, sub Q) made of
  loose CT adipose tissue binds the skin to the
  organs under it

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EPIDERMIS

• 4 layers
• stratum basale base layer
• stratum spinosum prickly layer
• stratum granulosum granular layer
• stratum corneum horny layer
• stratum lucidum clear layer
• can only be found on palms soles / thick skin

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EPIDERMIS

• the deepest layer of the epidermis, the stratum
  basale, contains cells that divide

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EPIDERMIS

• epidermal cells undergo keratinization as they
  mature are pushed toward the surface
• the outermost layer, the stratum corneum, is made
  of dead epidermal cells which are eventually shed
• 40 pounds in an average lifetime!
• Cornu horn
• Totally new epidermis in 25-45 days!

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EPIDERMIS

• the rate of cell division increases where skin is
  rubbed off regularly forming calluses corns
• the epidermis protects underlying tissues against
  water loss, injury, the effects of harmful
  chemicals

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EPIDERMIS

• melanin protects cells from the effects of UV
  light
• melanocytes (cells that make melanin) transfer
  melanin to epidermal cells which determines skin
  color

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SKIN COLOR

• genetically determined
• varies based on the kind amount of melanin
  produced, since all people have about the same
  number of melanocytes

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SKIN COLOR

• influenced by environment (exposure to sun)
• influenced by physiological factors (blood color,
  diet, chemicals such as bilirubin)

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DERMIS

• Composed of strong, flexible c.t.
• Corresponds to animal hides used to make leather
• dermis binds the epidermis to underlying tissues

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DERMIS

• fingerprints result from epidermal ridges
  projecting inward dermal papillae projecting
  upward
• genetically determined
• increase friction enhance gripping ability

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DERMIS

• dermal blood vessels supply nutrients to all skin
  cells help regulate body temperature
  (vasoconstriction, vasodilation)
• the dermis also contains hair follicles, sweat
  glands, sebaceous (oil) glands

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DERMIS

• nerve fibers are scattered throughout the dermis
• some carry impulses to muscles glands
• some are associated with sensory receptors in the
  skin, they carry impulses to the brain spinal
  cord

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DERMIS
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SUBCUTANEOUS LAYER

• made of loose CT adipose tissues
• it helps supply the skin with blood
• the adipose tissue helps conserve body heat

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ACCESSORY ORGANS OF THE SKIN?

• hair
• hairs develop in the follicles
• new cells push older cells closer to the surface
  where they become keratinized die
• hair color is genetically determined
• an arrector pili muscle attaches to each hair
  follicle this pulls the hair erect when
  stimulated goose bumps

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Functions of hair?

• To sense insects on skin
• Guards against physical
• trauma, heat loss, sunlight
• Eyelashes shield eyes
• nose hairs filter large particles from air

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ACCESSORY ORGANS OF THE SKIN?

• sebaceous glands
• glands that secrete sebum a mix of oil
  cellular debris
• sebum keeps skin hair soft, pliable,
  waterproof
• acts as a
• bactericide
• function begins
• at puberty

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ACCESSORY ORGANS OF THE SKIN?

• sweat glands sudoriferous glands
• exocrine glands which consist of a coiled tube
• eccrine sweat glands respond to elevated body
  temp.
• apocrine sweat glands respond to pain or
  emotional stress, function begins at puberty

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Apocrine sweat gland eccrine sweat gland
Nervous, anxious hot
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ACCESSORY ORGANS OF THE SKIN?

• 2.5 million, most in palms, soles, forehead
• modified sweat glands include mammary glands
  ceruminous glands in the outer ear canal

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ACCESSORY ORGANS OF THE SKIN?

• nails
• protective coverings for fingers toes
• each nail consists of a nail bed nail plate
• the white moon-shaped lunula at the base of the
  nail plate is the area where cells are most
  actively dividing
• again, cells become keratinized die as they age

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REGULATION OF BODY TEMPERATURE?

• vital because heat affects the rate of metabolic
  reactions
• heat is a product of metabolism
• skin constantly loses heat to the air

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REGULATION OF BODY TEMPERATURE?

• If temp is too high
• dermal blood vessels dilate
• sweat glands secrete sweat
• if temp is too low
• dermal blood vessels constrict
• sweat glands deactivate
• skeletal muscles contract involuntarily
  shivering

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HEALING OF WOUNDS?

• skin injuries trigger inflammation (red, warm,
  swollen, tender)
• dividing epithelial cells fill in shallow cuts
• clots close deeper cuts

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Wound healing
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HEALING OF WOUNDS?

• scabs clots dried tissue
• scars result from connective tissue replacing
  skin
• granulations form in large open wounds

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Homeostatic imbalances of skin

• Skin cancer?
• Basal cell carcinoma least malignant most
  common 30 of all white people get it
• Squamous cell carcinoma - often on scalp hands,
  grows rapidly and metastasizes
• Melanoma cancer of melanocytes, most dangerous
  type
• ABCD rule
• Asymmetry, border irregularity, color, diameter

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• Burns
• 1st degree epidermis is damaged
• ex. sunburn
• 2nd degree epidermis part of the dermis are
  damaged, blisters occur
• 3rd degree epidermis dermis hypodermis are
  all damaged, nerve endings are destroyed
• Evaluated by the rule of nines

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Effects of aging

• 1) Skin thins
• 2) Lubricating substances become deficient, so
  skin gets dry itchy
• 3) Elastic fibers clump, skin loses elasticity
• 4) Sub Q fat layer diminishes, often cold
• 3 4 cause wrinkles
• 5) Less melanocytes Langerhans cells enhance
  the risk of skin cancer
• 6) Hair thins due to fewer active hair follicles