Pathology

1. Shock - Pathology
With Diagrams and Explanations (Ref:
Robbins Pathologic Basis of Disease)

2. Definition of Shock
• Shock is a state of circulatory failure that
results in inadequate cellular oxygen
utilization.
• It leads to tissue hypoxia and cellular
dysfunction.
• Causes include severe hemorrhage, infections,
trauma, or myocardial infarction.

3. Classification of Shock
• 1. Hypovolemic Shock - due to blood/plasma
loss.
• 2. Cardiogenic Shock - due to pump failure
(e.g., MI).
• 3. Distributive Shock - includes:
• a. Septic Shock
• b. Anaphylactic Shock
• c. Neurogenic Shock
• 4. Obstructive Shock - e.g., pulmonary

4. Pathophysiology of Shock
• • Decreased tissue perfusion → Cellular
hypoxia.
• • Shift to anaerobic metabolism → Lactic
acidosis.
• • Cell membrane dysfunction → Cell injury.
• • Inflammatory mediator release →
Worsening shock.

5. Stages of Shock
• 1. Initial Stage: Hypoperfusion, no clinical
signs.
• 2. Compensated Stage: Activation of SNS,
tachycardia, vasoconstriction.
• 3. Progressive Stage: Worsening
hypoperfusion, acidosis, organ dysfunction.
• 4. Irreversible Stage: Severe hypoxia, multiple
organ failure, death.

6. Morphological Changes in Shock
• • Lungs: Congestion, alveolar damage.
• • Kidneys: Acute tubular necrosis.
• • Heart: Focal necrosis.
• • Liver: Centrilobular necrosis.
• • Brain: Ischemic injury.

7. Septic Shock - Key Features
• • Common cause of death in ICU patients.
• • Due to systemic infection → Inflammatory
response → Vasodilation.
• • Widespread endothelial activation → DIC
and multiorgan dysfunction.
• • Key mediators: TNF-α, IL-1, IL-6, Nitric oxide.