1. Environmental Diseases
By:
K.Mozaffari , MD, AP, CP

2. INJURY BY PHYSICAL AGENTS
Mechanical
Thermal

3. MECHANICAL TRAUMA Abrasion Contusion Laceration Incised wound
Puncture wound (Gunshot wounds)

4. Abrasion
Superficial epidermal tears
Bleeding under skin

5. Contusion (Bruise) Blunt object RBC extravasation Intact skin
discoloration

6. Laceration Tear or streching of tissue Jagged & irregular edges
Intact bridging Vessels

7. INCISED WOUND
Made by a sharp instrument
Bridging vessels are severed

8. Puncture Wounds Made by a long narrow instrument
Penetrating: pierces tissues
Perforating: traverses tissue to form an exit wound (Gunshot wounds)

9. Long distance & Close range

10. THERMAL INJURY
Thermal burns
Hyperthermia
Hypothermia

11. Thermal burns 5000 deaths/yr in the U.S Many victims are children
Factors:
Depth
Percentage
Inhalational injury
Effective therapy

12. Thermal burns A-Full-thickness: III & IV degree
Epidermis & dermal appendages lost
White, charred, dry or anesthetic
B-Partial-thickness:
I & II degree
Appendages are spared
Pink, mottled
& painful
Blisters form

13. If > 50 % of body surface: potentially fatal
If > 20 %: hypovolemic shock & edema
Inhalation of heat & gases
1-Water-soluble:
forms acids or alkalis with upper airway obstruction
(chlorine, sulfur oxides, ammonia)
2-Lipid-soluble:
deeper airways with pneumonitis
(nitrous oxide, plastics)

14. Burn sepsis →organ failure
(leading cause of death)
P.aeruginosa - S.aureus – Candida
Cellular & humoral defenses fail
Endotoxin from local site
Renal failure, ARDS & septic shock
Hypermetabolic state

15. Hyperthermia Heat exhaustion : most common, sudden onset
Heat Cramps: → Exercise leads to cramps
Electrolyte loss & nl core body temperature
Heat exhaustion : most common, sudden onset
water depletion→ collapse (spontaneously resolves)
Heat stroke: temperature & humidity
Sweating ceases → core body temperature:
Vasodilation ,muscle necrosis, arrhythmias & DIC

16. Hypothermia ambient & body temperature
At 90°F : loss of consciousness,
bradycardia & AF
Direct effects: crystals form
Indirect effects:
Slow onset ( Trench foot): edema & later atrophy with fibrosis
Sudden onset ( Gangrene) :ischemia & later exudation

17. ELECTRICAL INJURY Burns (amperage & path within body)
VF, cardiorespiratory arrest
Tetanic muscle spasm of chest wall
High voltage: Extensive burns, medullary paralysis

18. Electromagnetic fields ( EMFs )
The formerly believed relationship between increased risk of cancer & EMF failed to be confirmed
But when intense they can cause burns
Also interfere with pacemakers

19. Injury by ionizing radiation
Waves: X , δ
Neutrons & particles: proton, α , β
DNA is the most important target
types:
1-direct injury
2-indirect injury ( free radicals)
Lipids of cell membrane & enzymatic proteins are also targeted

21. Roentgen:
unit of X or δ that ionizes a specific volume of air (exposure measured)
Rad =1cGy (centigray):
100erg energy/g tissue absorbed
LET: (energy loss)
electron volt/µm
α > β > δ , X

22. α:restricted to a superficial area but with heavy damage
δ:less damage over a deeper course
Body cell types:
1)vulnerable,high turnover: GI,BM, lymphoid
2)slower turnover: liver ,endothelium
3)nondividing:myocardium,brain
Tissues have many cell types with complex effects ( vessels in the CNS)

23. Radiotherapy
Nl cells have faster repair than tumoral cells
Oxygen effect (free radicals): center of tumors are less vascular → less effective therapy
High dose given to a small field is better tolerated than small dose in larger fields
Alters gene expression :
MYC,FOS,TNF induction
TP53 activation : apoptosis

24. Morhpology Molecular level: DNA breaks lead to apoptosis by TP53
Deletion, translocation, fragmentation,
polyploidy, aneuploidy

25. Morhpology Nuclear level: Swelling, condensation, clumping, apoptosis
Giant cells, pleomorphism
At high doses, pyknosis & lysis are quick markers of cell death

26. Morhpology Cytoplasmic changes: Swelling mitochondrial distortion
ER degeneration
cell membrane breaks

27. Morhpology Early vascular changes:
dilation→ endothelial swelling, vacuolation, wall necrosis, thrombosis rupture→ endothelial proliferation & medial thickening→ luminal obliteration
Later, interstitial fibrosis leads to scarring & contractions

28. Acute vascular injury
Fibrinoid necrosis
edema

29. Chronic vascular injury
Subintimal fibrosis
Lumen is occluded

30. Radiation fibrosis of breast stroma
Pleomorphic residual
tumoral cells with multinucleation

31. Mediastinal fibrosis
Pericardium is thick after radiation in a case of lung ca

32. Chronic radiation dermatitis
Epidermal atrophy
Dermal fibrosis
Subcutaneous vessels
(telangiectasia)

33. Radiation effects on organ systems
Lymphopenia & shrinkage of lymphoid systems (thymus)

35. Radiation effects on organ systems
Granulocytes first rise, then fall to zero in the 2nd wk
Platelets are similarly affected but with some delay
Red cell precursors → anemia in 2nd -3rd wk
(RBCs are resistant )

36. Malignant transformation:
Sublethal high doses:
-Hiroshima & Chernobyl victims
-radiologists
Prolonged low-dose exposure:
-radon daughters (α) : lung ca

37. Total-Body Irradiation
Even small doses can be devastating
rad: acute radiation syndrome
Lethal range begins at 200 rads
Death is certain at 700 rads without Rx

38. syndromes
Dose (rad)
Manifestations
Hematopoietic
N&V
cytopenias
GI tract
Severe sx
diarrhea
Hemorrhage
Cerebral
>5000
Listlessness
drowsiness
Convulsions
Coma & death

40. MCQ 1
Which type of wound is produced by rubbing in which only the epidermal layer is removed?
1-laceration
2-abrasion
3-contusion
4-incision

41. MCQ 2 The primary target of ionizing radiation is? 1-RNA 2-DNA
3-Lipids
4-Proteins

42. MCQ 3 What is this lesion?

43. Abrasion

44. MCQ 4 Which cells are resistant to radiation?
1-gastrointestinal tract cells
2-lymphocytes
3-red blood cells
4-granulocytes

45. MCQ 5 A Full-thickness burn is not… 1-Pink, mottled, painful
2-anesthetic
3-III & IV degree
4-White, charred or dry

46. MCQ 6
What are the lesions?

47. Contusion (Bruise)

48. MCQ 7

49. laceration

50. Thank you
For Your Attention