genpathPhysInj

8/9/2019 genpathPhysInj

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Environmental Pathology:

physical injuries

Ma. Minda Luz M. Manuguid, M.D.



Physical injury: mechanical force

Mechanical force

S oft tissue injuries:

contusions, lacerations,

avulsions,

Bone injuries: fractures

Head injuries; coup &

contre-coup injuries,concussion, contusion



Physical injury: temperature changes

Tolerable range: 31-41°C

Hypothermia:

local freezing= Frostbite ± ischemic necrosis

S ystemic hypothermia= circulatory failure ±

marked vasoconstriction, slowing of metabolism,crystallization of intracellular water



Physical injury: temperature changes

Hyperthermia:

Heat stroke= peripheral vasodilatation, hypotension, CN S

dysfunction--- coma

Exertional= hyperK, metabolic (lactic) acidosis,

myoglobinuria, acute renal failure, DIC, RDS

Burns= partial & full thickness = plasma transudation,

hypovolemia, shock; sepsis: Pseudomonas aeruginosa;

Curling¶s ulcers, DIC, ATN, hemoconcentration

S moke inhalation: ARDS , pulmonary edema, intra-alveolar

hemorrhages



burns



Physical injuries: changes in

atmospheric pressure Changes in Atmospheric pressure

Blast injury: Air blast- bomb explosions;

Immersion blast- underwater

Altitude sickness: acute hypoxic injury;

chronic- anemia

Caisson disease



Physical Injuries: Electrocution

Electrical injur y

Factors: DC less harmful than AC; duration of

exposure, amperage/voltage, path of current-resistance of tissues, water content

Lightning: arborizing burns, organ rupture,

fractures, hemorrhages

Flashover



Physical injury: radiation

Ionizing Radiation- ph y sical transfer of energ y from its site of origin to the biologictargets, inducing ionization of its atoms:

Electromagnetic waves: x-rays, gamma rays Particles : neutrons & charged particles- alpha,

beta, protons, mesons, deuterons

S ources of Radiation:

background: galactic/solar cosmic rays, incl. UV,natural terrstrial radionucleides

man-made: diagnostic & therapeutic



Radiation

universal s y mbol ± radiation injuries



Physical injury: radiation

Quantitation of Radiation: R- roentgen

r ± rad- also called a ³centiGray´ (cGy)= energyabsorption of 100 ergs/gm of tissue (0.01 joule/kg)

G ± gray = 100 radsCi - curie

Linear energ y transfer (LET)

Relative biologic effectiveness (RBE)

Mechanisms of Radiation injur y :Target theory: direct damage to DNA

Indirect action theory: radiolysis of cellular water, production of free radicals= damage to DNA & cell membranes



Radiation injury

-ra y s ionizing particlesx-ra y s , , protons, etc.

IONIZ A TION & EXCIT A TION heat

Ox y gen effect CHEMIC AL CH A NGE free radicals

BIOLOGIC CH A NGE (DN A damage) DN A repair

malignant mutations inhibition of transformation cell division

C A NCER GENETIC EFFECTS CELL DE A TH



Physical injury: Radiation

Biologic effects of Radiation Effects are in direct proportion to mitotic/reproductive

activit y

V arious t ypes of radiation differ in penetrabilit y & patternof deposition of energ y

Ox y gen effects: amplifies low LET radiation damage;induces free radical production; fixation of radiantinjuries/lesions which would otherwise be reparable

Cellular: swelling, nuclear & c y toplasmic chromatinclumping, abnormal mitoses, aneuploid y , mitochondrialdistortion, ER degeneration; endothelial swelling,thrombosis, hemorrhage




Biologic effects of Radiation

Organ atroph y , esp. GI mucosa & hair follicles

L y mphopenia w/in hours, granuloc y topenia w/in 1 week; Anemia; Thromboc y topenia

Radiodermatitis: thin, atrophic skin; h yper- orde-pigmentation

Pulmonar y interstitial fibrosis Sterilit y : O varies more severel y affected than

Testes




Susceptibilit y of Tissues to Radiation injur y :

High: l y mphoid, hematopoietic, spermatogonia,ovarian follicles

Fairl y high: GI & mucosal epithelia, hair follicles,lung; late-kidne y

Medium: GIT wall, endothelium, glandularepitheliumof the breast & pancreas,

u.bladder epithelium, growing cartilage, bone, normal brain

Low: mature bone; mature cartilage; muscle;peripheral nerves



Radiation injury

Brain: adult-resistant; embr y onic-neuronal/glialdestruction

Skin: er y thema; edema; depigmentation;

atroph y ; cancer Lungs: edema; ARDS; interstitial fibrosis;

L y mph nodes: atroph y ; fibrosis

GIT: mucosal injur y , ulceration, fibrosis of wall

Gonads: destruction of germ cells

Blood & Bone marrow: thromboc y topenia,granuloc y topenia, anemia, panc y topenia



Acute whole body radiation

10-50 rads: no obvious effect; minor bloodchanges

50-100 rads: vomiting & nausea for 1 da y in5-10%; fatigue; transient reduction in

l y mphoc y tes & neutrophils 100-200 rads: vomiting & nausea for 1 da y in

20-50%; about 50% reduction inl y mphoc y tes & neutrophils

200-350 rads: vomiting & nausea in nearl y all; anorexia, diarrhea, minor hemorrhages;about 20% die w/in 2-6 wks after exposure;convalescence is about 3 mos.up to 75%reduction in all circulating blood elements



Acute whole body radiation

350-550 rads: about 50% die w/in 1 month;convalescence is about 6 mos.

550-750 rads: vomiting & nausea in all w/in 4

hrs; up to 100% die; few survivors convalescefor 6 mos

1000 rads: vomiting & nausea in all w/in 1-2hrs; all die w/in da y s

5000 rads: almost immediate incapacitation;all die w/in 1 week



Thank you !

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