Transcript Integumentary AKA Skin

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
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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