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Pathobio Exam 1
Set 11: Therman & Radiation Injury
62
Pathology
Graduate
10/18/2011

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Cards

Term
What are the 3 types of thermal injury?
Definition
1) Thermal burns
2) hyperthermia
3) hypothermia
Term
*Why are the number of thermal burn deaths decreasing?
Definition
smoke detectors, hot water temp regulators, imoprovements in burn care, flame-retardent sleepwear
Term
What can cause thermal burns?
Definition
1) flame/flash
2) scalding from hot liquids
3) contact with hot object (iron, cigarette)
4) steam/gas
5) electricity
Term
What are the 3 classifications of thermal burns?
Definition
1) superficial
2) partial-thickness
3) full-thickness
Term
def

superficial burns
Definition
injury limited to epidermis (i.e. sunburn)
Term
def

partial-thickness burn
Definition
1) damage extends to the dermis (blisters frequent)

2) adnexal (appendage) structures injured, but can regrow
Term
def

full thickness burns
Definition
deeper injury with destruction of the epidermis, dermis, & subcutaneous tissue.

Can extend to tendons, skeletal muscle & bone
Term
What type of necrosis affects thermal burns?
Definition
coagulative
Term
What is the pathology of superficial & partial-thickness burns?
Definition
typical acute inflammatory response (hyperemia, exudative edema, infiltration by neutrophils & macrophages, pain)
Term
What is the pathology of full-thickness burns?
Definition
extensive damage to superficial blood vessels, never endings & adnexal structures => white or black dry, lethery, insensate wounds
Term
*does morbidity & mortality of thermal burns depend on?
Definition
extent & depth of burns, inhalation &/or coexistent traumatic injuries, age, pre-existent medical conditions, & adequacy of Tx
Term
What 6 complications can arise in thermal burns?
Definition
1) hypovolemic shock
2) hyperkalemia
3) sepsis
4) resp. failure
5) gastric ulcers
6) chronic complications
Term
How is % of body covered in burns estimated clinically?
Definition
Rule of 9's (don't need to know now)
Term
When is hypovolemic shock a concern in burn victims?
Definition
first 24 hours
Term
Why are fluids lost in thermal burns => hypovolemic shock?
Definition
1) increased vasular permeability => loss of fluid into interstitum

2) evaporation due to loss of skin
Term
What causes hyperkalemia in thermal burns?
Definition
cellular disruption from the heat
Term
What causes spesis in thermal burns?
Definition
loss of skin barrier & decreased inflammatory response => wound infections => bacteremia => septic shock with multisystem organ failure
Term
What can cause resp. failure in thermal burns?
Definition
inhalation injury
pneumonia
diffuse alveolar damage
Term
Why are gastric ulcers a concern in patients with thermal burns?
Definition
can lead to upper GI bleeding
Term
What 2 chronic complications can arise from thermal burns?
Definition
1) excessive scar formation
2) contractures (esp. in children)
Term
What are the effects of hyperthermia dependent on?
Definition
duration of exposure , humitidy of the air, adequacy of fluid/electrolyte replacement, age, level or exertion, current medical conditions
Term
What are the 3 effects of hyperthermia?
Definition
1) Heat cramps
2) heat exhaustion
3) heat stroke
Term
Sx

Heat cramps
Definition
intermittent, involuntary, painful muscle spasms during or after strenuous exercise - often in hot environments
Term
What causes heat cramps?
Definition
electrolyte abnormalities
Term
Sx

Heat exhaustion
Definition
relatively sudden onset of dizziness, neausea, headache, profuse sweating, & fatigue associated with hypotension, tachycardia & low-grade fever

skin usually pale, cool, & moist
Term
What causes heat exhaustion?
Definition
inadqeuate compensation for hypovolemia & elevated body temp
Term
*What's the most severe form of hyperthermia?
Definition
heat stroke - potentially like-threatening
Term
Sx

heat stroke
Definition
extremely high core body temp associated with hot, dry, flushed skin
tachycardia
difficulty breathing
neurological Sx
may progress to multi-organ failure & rhabdomyolysis
Term
What are the differences between heat stroke & heat exhaustion seen in a patient?
Definition
Heat stroke: dry, hot skin. high body temp
heat exhaustion: moist clammy skin, normal/subnormal temp
Term
What causes heat stroke?
Definition
inability for heat dissipation fast enough => markedly elevated body temp => denaturation of proteins/cell membranes, alteration in HSP (heat shock protein) expression, amplified acute phase response => thermoregulatory failure
Term
What do the effects of hypothermia depend on?
Definition
duration of exposure, wind, moisture, age, weight, current medical conditions
Term
Sx

hypothermia
Definition
shivering, loss of motor coordination, slurred speech, confusion, drowsiness, apathy, irrational behavior, progressive loss of consciousness, focal tissue injury => cardiorespiratory failure & death
Term
*What 4 places on the body are likely to see focal tissue injury due to hypothermia?
Definition
1) ears
2) nose
3) fingers
4) toes
Term
What is the pathogenesis of focal tissue injury in hypothermia?
Definition
peripheral vasoconstriction, interstitial fluid crystalization w/ cellular dehydration & protein denaturation, increased vascular permiability, & thrombosis
Term
What are the 4 consequences of focal tissue injury due to hypothermia?
Definition
1) frostbite => 2) gangrene
3) trench (immersion) foot
4) chilblains (perniosis)
Term
Sx

frostbite
Definition
initially affected areas appear pale & have associated burning & clear blisters.

increasing severity: leisons become discolored (red => purple => black), swollen, firm, & ulcerated with eventual loss of sensation
Term
What causes trench (immersion) foot?
Definition
prolonged exposure to cold, damp, unsanitary conditions with constrictive footware => vascular, soft tissue & nerve injury with secondary infections
Term
def

chilblains (perniosis)
Definition
abnormal vascular reaction to cold
Term
Sx

chilblains (perniosis)
Definition
small, prutitic, swollen, painful skin leisons (red => blue) that develop upon re-warming
Term
What are the 3 ways radiation can be measured?
Definition
1) emitted radiation
2) absorbed radiation
3) biological effect of radiation (equivalent doses)
Term
def

emitted radiation
Definition
decay of a radionuclide per second
Term
def

absorbed radiation
Definition
energy absorbed per tissue mass
Term
def

biological effect of radiation
Definition
product of the absorbed dose & the Quality Factor (depends on the type of radiation)
Term
What are the units of emitted radiation (conventional & SI)?
Definition
c: curie [Ci]
SI: becquerel [Bq]
Term
What are the units of absorbed radiation (conventional & SI)?
Definition
c: rad
SI: gray [Gy]
Term
What are the units of biological effect of radiation (conventional & SI)?
Definition
c: rem
SI: sievert [Sv]
Term
What are the 3 additional factors that determine radiation's biologic effects?
Definition
1) Rate of delivery
2) extent of exposure
3) tissue vulnerability
Term
Why does rate of delivery of radiation affect the biological effect?
Definition
there may be time for cellular dependent depending on how fractioned the doses are
Term
def

extent of radiation exposure
Definition
field size
Term
What 3 factors affect tissue vulnerability to radiation?
Definition
1) rate of cellular proliferation
2) availability of oxygen
3) extent of vascular injury
Term
Are tissues with high cellular turnover more or less susceptible to radiation damage?
Definition
more
Term
Are well oxygenated tissues more or less vulnerable to radiation injury?

Why?
Definition
more b/c oxygen-derived free radicals exert the greatest damage to DNA
Term
Are acute or chronic effects of radition seen in vessels?
Definition
both
Term
What are the areas of the cell that are affected by radiation?
Definition
nucleus & cytoplasm
Term
What happens in the nucleus when exposed to ionizing ration & resultant free-radical formation?
Definition
DNA damage & attampted repair =>

1) DNA recovery
2) persistant DNA abnormalities => apoptosis or perpetual alterations
Term
What happens in the cytoplasm when exposed to ionizing ration & resultant free-radical formation?
Definition
cellular swelling, injury to plasma & organelle membranes
Term
What is the pathology of early radiation complication?
Definition
1) reversible & irreversible parenchymal cell injury, particularly in susceptible tissues

2) endothelial damage => hyperemia, increased vascular permeability, hemmorhage & thrombosis
Term
What is the pathology of late radiation complication?
Definition
1) vascular & intestinal fibrosis w/ associated tissue atrophy & telangiectasia => secondary complications
2) cataracts
3) malignancies
4) CV disease
5) teratogenic effects
Term
def

cataracts
Definition
lens opacities
Term
*What malignancies are seen due to radiation therapy?
Definition
laukemias, breask carcinoma, papillary thyroid carcinoma (esp. exposed children)
Term
What teratogenic effects can be seen in radiation injury?
Definition
impaired physical & mental development
Term
What is the pathology of early & late radiation complication?
Definition
radiation-induced cytologic atypia (inc. enlarged, hyperchromatic, pleomorphic nuclei)
abnormal mitotic figures
bizarre giant cells
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