The Integumentary System

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The Integumentary System

• Chapter 5

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The Integumentary System

• The parts of the integument
• Skin
• Sweat and Oil glands
• hairs
• Nails

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The Integumentary System The Skin

• The skin is pliable yet tough, allowing it to
  take constant punishment from external organs.
• Facts
• Covers 2.2 meters, weighs 4 to 5 kg, and accounts
  for about 7 of total body weight in the average.
• Thickness varies from 1.5 to 4.0 mm or more in
  some areas.
• Millions of dead cells rub off daily
• A totally new epidermis every 25 to 45 days
• The average person sheds 18kg (40lbs) of skin
  flakes in a lifetime

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The Skin
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The Skin Epidermis

• The epidermis is a keratinized stratified
  squamous epithelium consisting of four distinct
  cell types or five distinct layers.
• Cells of the epidermis
• 1. Keratinocyte produce keratin
• 2. melanocyte produce melanin
• 3. Langerhans cell are macrophages
• 4. Merkel cells (epidermal dendritic cells)
  function as a sensory receptors for touch

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Layers of the Epidermis

• Thick skin covers the palms, fingertips, and
  soles of the feet
• Five Layers (strata) from deep to superficial
• 1. stratum basale
• 2. stratum spinosum
• 3. stratum granulosum
• 4. stratum lucidum
• 5. stratum corneum

• Thin skin covers the rest of the body
• stratum lucidum is absent and the other strata
  are thinner

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The SkinDermis

• The dermis, composed mainly of dense, irregular
  connective tissue, is well supplied with blood
  vessels, lymphatic vessels, and nerves.
• Cutaneous receptors, glands, and hair follicles
  reside within the dermis

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Layers of the dermis

• From superficial to deep
• 1. papillary layer exhibits dermal papillae that
  protrude into the epidermis above and the
  epidermal ridges that produce fingerprints.
• 2. reticular layer is thicker and the connective
  tissue fibers are much more densely interwoven.

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Skin Color

• Skin color reflects the amount of pigments
  (melanin and carotene) in the skin and the
  oxygenation level of hemoglobin in blood
• 1. Melanin is the only pigment made in the skin.
  
• ranges in color from yellow, redish brown, to
  black
• Stimulated by exposure to ultraviolet radiation
  in sunlight and protects the nuceli from damaging
  effects of UV radiation

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Homeostatic Imbalance

• 1. stiae stretch marks
• Tears in the dermis
• 2. blisters separation of dermis and epidermis

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Homeostatic imbalance

• Excessive sun exposure can
• cause clumping of elastin fibers, leading to
  leathery skin,
• temporarily depresses the immune system
• Alter the DNA of skin cells which may cause cancer

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Homeostatic Imbalance

• 1. Cyanosis poorly oxygenated blood

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Homeostatic imbalance

• Redness, or erythema redding of skin
• Pallor or blanching

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Homeostatic balance

• Jaundice or yellow cast

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Homeostatic imbalance

• Bronzing

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Homeostatic imbalance

• Black-and-blue marks bruises hematomas

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Appendages of the Skin

• Skin appendages, which derive from the epidermis,
  include
• Hairs
• Hair follicles
• Nails
• Glands

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Sweat (Sudoriferous) Glands

• Found all over the body except the nipples and
  the external genitalia
• More than 2.2 million per person

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Sweat glands Eccrine glands

• Merocirne glands
• Found over most of the body
• Thermoregulation
• Sweat is 99 water
• Salts, Vit C., antibodies, metabolic wastes and
  lactic acid

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Sweat Gland apocrine

• Largely confinded to the axillary and anogenital
  areas
• Larger than eccrine glands and their ducts empty
  along hair follicles
• Start production around puberty
• Function is unknown
• Cerunminous glands
• Mammary glands

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Sebaceous (oil) glands

• Located all over body except palms of hands
• Sebum
• Functions to softens and lubricates the hair and
  skin
• Prevents hair from becoming brittle, and slows
  water loss from the skin
• Bacterialcidal action

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Homeostatic imbalance

• Whiteheads
• Blackheads
• Acne
• Seborrhea cradle cap

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Hairs and Hair Follicles

• Hair
• main function is sensory protection