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_________ wounds are defined as those that do not penetrate the epithelium. In this case, dividing cells of the ______ ______ migrate into the "pit" of the wound, if necessary, then the normal process of cell division produces nucleated ___________ and finally these get pushed upward by the newly-divided keratinocytes as they mature into _________.
Superficial; stratum basale; keratinocytes; corneocytes
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____ wounds penetrate blood vessels. Blood fills the wound and then _____ into semi-solid mass. ________ in the clot mature into macrophages; neutrophils in the clot work with macrophages to destroy invaders. Cells of the _____ _____ migrate inward to replace the epidermis. _________ migrate into the dermal portion of the clot and lay down a new fiber matrix to restore the function and appearance of the ______. If the restoration of the dermis is not complete, a ____ may be left behind. Some scars ______ over a period of several months or even years.
Deep; clots; Monocytes; stratum basale; Fibroblasts; dermis; scar; remodel
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________ ______ are another lesion that results from disruption in skin homeostasis.
Pressure ulcers (decubitus ulcers)
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What areas are prone to pressure ulcers and why?
Areas where the bone is close to the surface;
because there is less cushioning from adipose and muscle tissue. The skin becomes trapped between a fixed point and the blood supply is lost.
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A few hours of lost blood supply may produce a discoloration of the affected area, but damage is not _______. If the pressure continues for a longer time, small cracks develop in the skin and the _____ _____ begin dividing.
permanent; skin flora
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Without the immune cells carried by the blood, the infection spreads throughout a large area and tissue ______ (death) results.
Necrosis
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First degree burn
only the epidermis is involved. The skin reddens, but there is no permanent damage and the skin returns to normal in under a week.
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Second degree burn
the heat energy penetrates deeply and both the epidermis and deris are damaged. Blood vessels leak fluid (not the cells), and blisters form as the skin fills with the filtrate of blood. Hair follicles and glands are typically not damaged.
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Third degree burn or full-thickness burn
destroys all layers of the skin. Cells die and the skin function is lost in the affected area. The dead skin may be black, cherry-red, or ash-white.
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There are __ regions of 9% each
11; the remaining 1% is the perineum
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_______ are located in the core; they sense the temperature of blood. The control center is the __________, a part of the brain. There are several effectors. The _____ is a major effector in the homeostatic loop controlling body temperature.
Receptors; hypothalamus; skin
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Two primary thermoregulatory mechanisms
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Blood vessels dilate to ____ heat, constrict to ______ heat.
shed; conserve
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_______ ____ also helps constrict blood vessels ("goose bumps")
Arrector pili;
-in animals with fur, hairs trap air and provid insulation
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Adipose tissue in __________ _____ insulates these blood vessels
subcutaneous layer;
Sweat glands (apocrine and eccrine) shed heat by evaporation
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If the body wishes to shed heat to maintain homeostasis, _____ ______ release fluid to the surface to cool the skin by evaporation.
sweat glands
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Blood vessels _____ and shed more heat to the environment. This makes the skin appear _____ or even ___ in light-skinned people. The same reaction can happen in response to emotional events, and is called _______.
dilate; pink; red; blushing
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When blood is too cold, heat is _______. Sweat glands stop production, and blood vessels ________. Blood stays internal to the dermis, behind the insulating layer of fat in the ________ ______. The skin may appear ____ or even ____ as blood is trapped deep in the dermis and in the ___________ _______.
conserved; constrict; subcutaneous layer; pale; blue; subcutaneous region
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Melanocytes are normally scattered more-or-less evenly throughout the epidermis, mostly in the deeper layers. When they accumulate in one region, a ____ results.
mole (or nevus)
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A mole with uneven color or irregular edges or both can be a symptom of _____ ______, ________ _______.
skin cancer; malignant melanoma
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All suspicious moles should be biopsied. Because the respons of skin to strong __ light is to make more _____, and __ can damage DNA resulting in cancer, any tanning also carries alon with it an increased risk of cancer.
UV; melanin; UV
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Skin Cancer
Basal Cell Carcinoma:
-Most common type of skin cancer
-Commonly seen on face
-Caused by sun exposure
-Cancerous but rarely metatstatic (does not travel to distant sites
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Skin Cancer
Squamous Cell Carcinoma:
-Second most common type of skin cancer
-Commonly seen on face
-Caused by sun (UV) exposure
-Cancerous and will metatstasize (travels to distant sites, usually through lymphatic system)
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Skin Cancer
Melanoma:
-Worst prognosis of any skin cancer
- -Frequently metastasizes
- --if it has traveled to lymph nodes, then 5yr survival less than 1 in 3.
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- --ABCDE criteria: asymmetry, border, color, diverse structure, elevation
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Xeroderma Pigmentosum:
-Not a cancer, but a predisposition to cancer
-These patients have a mutation in the gene that helps repair DNA damage.
-DNA damage is constant and is usually repaired without incident.
-In these people, lacking DNA repair, multiple skin cancers are common.
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Skin has normal flora, and is constantly being shed
- of the 600,000 squames (dead skin cells) shed per hour per person, 7% (42,000) are contaminated with viable organisms.
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Handwashing and ascohol-based hand cleaners are used to reduce number of viable organisms
-Different sensitivity for encapsulated viruses, unencapsulated viruses, bacteria and fungi so no one method is "best"
-Iodin scrubs used for patients; effective, but too harsh for regular us on hands
- -60-95% alcohol best for caregivers
- (effective against all micro-organisms)
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The most common organisms found associated with shed skin are
Staphylococcus and Enterococcus, which resist drying and live for a long time
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_________ are bacteria which commonly cause pneumonia in hospitals.
Klebsiella
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