Emergency Care in the Streets - Chapter 9: Pathophysiology

Understanding Cellular Changes and Homeostasis

• Cellular changes in response to stressors are crucial for patient evaluation and treatment.
• Homeostasis failure leads to disease development.
• Pathophysiology: study of organism function in disease presence.
• Key cellular terms:
  • Atrophy: Decrease in cell size.
  • Hypertrophy: Increase in cell size.
  • Hyperplasia: Increase in number of cells.
  • Dysplasia: Alteration in cell size/organization.
  • Metaplasia: Reversible cell adaptation.

Body Fluid Composition and Balance

• The human body is primarily water; homeostasis can be disturbed by factors like dehydration or excessive salt intake.
• Fluid intake and loss:
  • Adults take in about 2.5 liters of water daily.
  • Water is lost through urine, skin, lungs, and feces.

Disturbances in Fluid Balance

• Edema: Fluid buildup in interstitial space.
  • Types: peripheral, sacral, and ascites.
  • Causes include increased capillary pressure or lymphatic obstruction.
• Tonicity: Water movement pressure on cells.
  • Isotonic: Cells remain unchanged.
  • Hypertonic: Cells shrink.
  • Hypotonic: Cells swell.

Electrolyte Imbalances

• Sodium (Na):
  • Normal levels: 136-144 mEq/L.
  • Hypernatremia: High sodium, often due to dehydration.
  • Hyponatremia: Low sodium, often due to excessive sodium loss.
• Potassium (K):
  • Normal levels: 3.5-5 mEq/L.
  • Hypokalemia: Low potassium, causes muscle weakness.
  • Hyperkalemia: High potassium, life-threatening cardiac issues.
• Calcium (Ca):
  • Normal levels: 8.5-10.5 mg/dL.
  • Hypocalcemia: Causes muscle spasms, seizures.
  • Hypercalcemia: Causes constipation, can lead to coma.
• Magnesium (Mg):
  • Normal levels: 1.5-2.1 mEq/L.
  • Hypomagnesemia: Causes muscle cramps.
  • Hypermagnesemia: Causes muscle weakness.

Acid-Base Balance

• Acidosis: Increase in H+ ions.
• Alkalosis: Decrease in H+ ions.
• Types:
  • Respiratory Acidosis: Due to hypoventilation.
  • Respiratory Alkalosis: Due to hyperventilation.
  • Metabolic Acidosis: Often from diabetes complications.
  • Metabolic Alkalosis: Often from excessive loss of stomach acid.

Cellular Injury and Death

• Causes: Hypoxia, chemical, infectious, immunological, and physical.
• Mediators like free radicals cause extensive damage.
• Necrosis: Cell death processes, results in tissue breakdown.

Hypoperfusion and Shock

• Hypoperfusion: Reduced blood flow, leads to shock.
• Types of shock:
  • Central: Cardiogenic and obstructive.
  • Peripheral: Hypovolemic and distributive.
• Management: Focuses on improving perfusion and oxygen delivery.

Immune System and Inflammation

• Anatomic Barriers: Skin, respiratory tract.
• Immune Response: Cellular interactions against pathogens.
• Inflammatory Response: Vascular changes to fight infection.
• Types of hypersensitivity (allergic) reactions.

Risks and Influences on Disease

• Genetic and Environmental Factors: Influence disease development.
• Age and Sex: Affect disease risk and presentation.
• Psychosocial Factors: Stress can exacerbate conditions.

Conclusion

• Comprehensive understanding of pathophysiology is essential for effective emergency medical care.
• Future chapters will cover more detailed aspects of paramedicine.