Transcript Integumentary

Integumentary AKA Skin
Introduction
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Skin comprises the largest organ system
in the body
Weighs approximately 17 Kg
Takes up 2.0 square meters
Functions
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Regulates body temp.
Acts as an excretory 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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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Decubitus Ulcers – AKA bed or pressure
sores
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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
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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
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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
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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