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					Integumentary AKA Skin
Introduction
 Skin comprises the largest organ system in
  the body
 Weighs approximately 17 Kg
 Takes up 2.0 square meters
Functions
 Regulates body temp.
 Acts as an extretory organ
 Stores chlorides
 Manufactures vitamin D which is essential
  for the mineralization of bones and teeth
 Serves as the most extensive and varied of
  the sense organs – high concentration of
  sensory receptors, especially where this is
  critical – lips, finger tips
The Envelope
 Prevents the loss of essential host constituents or
  the entry into the host of toxic physical, chemical
  and microbiotic agents
 Properties go beyond a mere envelope
   – Is waterproof and prevents the evaporation and escape
     of tissue fluids
   – Becomes thick when subjected to rough treatment
   – Fastened down where most likely to be pulled off
   – Has friction ridges to lessen slippage – e.g., finger tips
Anatomy
 Non-Homogeneous
 Large differences in form, color, and
  consistency in various parts of the same
  body
 Three distinct types of tissue – epidermis,
  dermis, and subcutaneous
Epidermis
 Ectodermal embryonic origin – two basic layers –
  superficial and deep
 Two main cell types are Melanocytes or pigment
  cells and Karatinocytes or epithelial cells
 Superficial layer is called the Stratum Corneum
   – Dead layer, less than 1 micrometer thick
   – Consists of several strata of dry, flattened, scaly cells
     without visible nuclei
   – The surface cells are perpetually being rubbed away
     and replaced by cells from the next layer – the
     Germative layer
Epidermis
Epidermis
Germative Layer
 AKA Basal Layer
 This layer is living
 Cell division occurs here and the cells
  biochemically and functionally mature as they
  ascend through the more superficial layers
 Elapsed time from the cell division to shedding is
  at least 4 weeks – in abnormal states such as
  psoriasis = may turn over in 4 days
Dermis
 Has a mesodermal embryonic origin,
  similar to CT
 Primarily made up of collagen, elastin, and
  reticulin fiber
 Dermis accounts for 5% of body mass
 The outer aspect of dermis nearest to the
  epidermis is called the papillary dermis –
  rich in nerves, vessels, and various sensory
  receptors
Dermis
Dermis
 The deeper dermis is called the Reticular
  Dermis that contains the cutaneous vascular
  network
 These vessels subserve the
  thermoregulatory functions
 Also, there are more neuroreceptors and
  lymph glands
Subcutaneous Tissue
 Deep to dermis
 Fatty structure of various thickness
 Functions as a thermal barrier and
  protective cushion
 AKA superficial fascia or tela subcutanea
Subcutaneous Tissue
Skin Color
 Due primarily to melanin, a pigment in the
  epidermis and to carotene, a pigment in dermis as
  well as the blood in the capillaries of the dermis
 Melanin is synthesized in cells called melanocytes
  – found in basal layer
 Number of melanocytes is essentially the same in
  all races. Therefore, differences in skin color due
  to the amount of pigment the melanocytes produce
  and disperse
 When skin is exposed to ultraviolet radiation –
  enzymatic activity is increased and both the
  amount and darkness of melanin increase and the
  skin darkens as a protective measure
Sweat Glands
 Two types – eccrine and sebaceous
 Eccrine – produce watery sweat that reaches the
  surface of skin – found in very high concentration
  throughout the body and serve to regulate
  temperature
 Sebaceous – are outgrowths of hair follicles into
  the dermis
   – Are filled with cells which secrete greasy substance
     called sebum and give skin a greasy feels and make the
     skin waterproof
   – Are found in high concentration in upper torso
Sweat Glands
Hairs
 Are distributed throughout the whole body except
  selected areas
 May be short or long
 Have a shaft which projects beyond skin surface, a
  root that lies in a follicle of the skin and a bulb
 Hairs last 2-4 years on head, 3-5 months on an
  eyelash
 The erector pili muscles are bundles of smooth
  muscle that pass next to the hairs, are involuntary,
  cause hairs to stand up, typically an ANS reaction
  to fear
Hairs
Hairs
Brief Overview of Burns
 1st degree – damages only epidermis, a
  sunburn with reddening of the skin
 2nd degree – burn destroys much of the
  epidermis but leaves some epidermal
  remnants
  – Re-growth from remnants is possible
  – Blisters are common and pain is often severe
    since the skin nerves are irritated by the
    products of cellular destruction
1st Degree Burn
2nd Degree Burn
Burns
 3rd Degree – reaches to and thru dermis –
  often exposing muscle and bone
 No epidermal remnants are present
 Little or no feeling because of destruction of
  nerves
 Treatment requires skin grafts to provide
  epidermal cells
 Healing is slow at best
3rd Degree Burn
Major Problems of Burns
 Infection
 Maintaining fluid
 Maintaining electrolyte balance which
  requires food and fluid intake
 Contractures of skin and underlying CT and
  muscle (all soft tissue) due to intense
  scarring
Other Common Problems with
Skin
 Decubitus Ulcers – AKA bed or pressure
 sores
  – Caused by constant deficiency of blood to
    tissues overlying a bony prominence subjected
    to prolonged pressure – especially if CNS or
    PNS not functioning fully
  – Tissue breakdown leads to infection, necrosis,
    etc.
Heel Decubitus ulcer
Deep Lesion
1st Level of Healing
Healing
Further Healing
Skin Problems
 Skin Cancer
 Prolonged overexposure to sunlight is primary
  cause with higher risk for fair skin
 South and southwest have higher incidence
 Main types
 Basal Cell – most common
   – Appears as small, shiny, fleshy nodules on the head,
     neck and/or hands
   – Untreated, the nodular lesions will begin to bleed, crust
     over, and repeat the cycle
   – Does not metastasize – may cause localized destruction
     of tissue
Basal Cell
Problems
 Squamous Cell
 Nodules or red, scaly, plate-like patches that
  are sharply outlined
 Typically develops on ear, lips, mouth and
  can metastasize
 Cure rate for basal and squamous is 95% if
  treated
Squamous Cell
Squamous Cell
Problems
 Melanoma
 Uncommon
 Serious, can metastasize, can lead to death
 Appears as a dark brown or black mole-like
  growth with irregular borders and irregular
  pigmentation
 Lesions may turn shades of gray, blue and white
 Most common sites are upper back in males and
  female, anterior body in males, lower legs in
  females
Melanoma
Melanoma
Melanoma
Study Points
 Layers
 Cells
 Basic Terminology for burns
 Three primary types of cancer

				
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posted:8/23/2012
language:English
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