Notes on Environmental Pathology

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Leading causes of disease:

• Alcohol and tobacco.

Tobacco use causes:

• CV disease, lung cancer, stroke.

• Nicotine is the most addictive substance in tobacco.

• This also includes chewing tobacco and second-hand (passive) smoke.

Alcohol use:

• Stomach absorption.

• Metabolism in liver and stomach.

• Alcohol dehydrogenase is the rate-limiting metabolism enzyme.

Products of alcohol metabolism:

• Reduced NADH.

• Acetyl CoA.

• Alcohol induction of cytochrome P-450 increases alcohol metabolism, increasing tolerance.

• Females have less gastric alcohol dehydrogenase.

Lab findings in alcohol abuse:

• Fasting hypoglycemia: pyruvate, which is a substrate for gluconeogenesis, is converted to lactate.

• Increased anion gap metabolic acidosis.

• Other findings: Hyperuricemia, hypertriglyceridemia, AST greater than ALT, increased GGT.

Other drugs:


• Stimulant; mydriasis, tachycardia, hypertension, AMI, CNS infarction.


• Opiate; miotic pupils, frothing at mouth, nephrotic syndrome.


• Stimulant; red conjunctiva, euphoria, delayed reaction time.

Complications of IV drug abuse:

• Hepatitis B, HIV, tetanus, infective endocarditis.

Overall effects of drugs:

• Cerebral atrophy; damaged neurotransmitter sites.

Adverse effects of certain medications:


• Damage to liver and kidneys; production of free radicals.

Aspirin (also known as acetylsalicylic acid or salicylate) overdose:

• Tinnitus, vertigo, altered mental status, tachypnea, respiratory alkalosis, metabolic acidosis with increased anion gap, hyperthermia, hemorrhagic gastritis, fulminant hepatitis.

Exogenous use of estrogen without progesterone:

• Cancer, venous thromboembolism, intrahepatic cholestasis with jaundice, myocardial infarction, stroke.

Use of oral contraceptives:

• Cancer, venous thromboembolism, folate deficiency, hypertension, hepatic adenoma, intrahepatic cholestasis with jaundice, cholesterol gallstones.

Types of wounds:

• Contusion, abrasion, laceration, incision.

Thermal injury:


• Eg., sunburn; heal without scarring.


• Blister formation; usually heal without scarring.


• Painless; full thickness burns.

• Scarring is inevitable.

• Keloids and potential for developing squamous cell carcinoma.

P. aeruginosa

• Infection is common in burn victims.


• Damage by ice crystallization in cells.

• Loss of pain; waxy appearance.

Electrical shock injury:

• Alternating current is more damaging than direct current.

• AC produces tetanic contractions and DC produces a single shock.

High-altitude injury:

• Respiratory alkalosis activates glycolysis.

• Increased 2,3-BPG synthesis.

• Right-shifts O2 binding curve; more oxygen dumped in tissues.

Acute mountain sickness:

• Headache, fatigue, dizziness, anorexia, insomnia; pulmonary and cerebral edema.



• Initial laryngospasm, hypoxemia, damage to pneumocytes.


• Asphyxia.


• Hypoxemia with damage to heart, CNS, kidneys, lungs.

Diving reflex activated in cold water drowning:

• Blood shunted from periphery to central core.

Ionizing radiation injury:

• DNA damage and formation of hydroxyl free radicals.

• Most sensitive tissues: lymphoid, bone marrow, mucosa of GI tract; germinal tissue.

• Least sensitive tissues: bone, brain, muscle, skin.

Radiation has effects in the areas of:

• Hematopoietic, vascular, epidermal, and GI.

• Susceptibility to cancers.

Non-ionizing radiation:

Ultraviolet light B:

• Pyrimidine dimers.

• TP53 inactivation and RAS activation.

• Sunburn.

• Susceptibility to cancers.

Effects of radiation:


• 3rd degree burns.


• Burns, cataracts, sterility.


• Burns, cataracts.

Additional Reading:

Basic Pathology

1. Cell Injury
2. Inflammation and Repair
3. Immunopathology
4. Water, Electrolyte, Acid-Base, Hemodynamic Disorders
5. Genetic and Developmental Disorders
6. Environmental Pathology
7. Nutritional Disorders
8. Neoplasia
9. Vascular Disorders
10. Heart Disorders
11. Red Blood Cell Disorders
12. White Blood Cell Disorders
13. Lymphoid Tissue Disorders
14. Hemostasis Disorders
15. Blood Banking and Transfusion Disorders
16. Upper and Lower Respiratory Disorders
17. Gastrointestinal Disorders
18. Hepatobiliary and Pancreatic Disorders
19. Kidney Disorders
20. Lower Urinary Tract and Male Reproductive Disorders
21. Female Reproductive and Breast Disorders
22. Endocrine Disorders
23. Musculoskeletal Disorders
24. Skin Disorders
25. Nervous System Disorders
26. Notes on Tissue Regeneration
27. A Table of Bleeding Disorders
28. FAQ on Structure and Function of Red Blood Cells
29. FAQ on Components of Blood
30. Notes on Hemostatic Mechanisms
31. What is Fever?
32. What is Edema?
33. FAQ on Blood Pressure
34. FAQ on principles of fluid and flow dynamics of Blood
35. Causes of Thrombocytopenia
36. Squamous cell carcinoma of head and neck mucosa
37. Four tumors which never metastasize to the brain
38. What is caustic injury?
39. What causes Peripheral Edema?

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