Acute Inflammation is a high-yield inflammation topic for INI CET (AIIMS PG).
Definition: Inflammation is the protective vascular and tissue response to injury, aimed at removing the injurious agent and limiting tissue damage.
Cardinal Signs of Inflammation (Celsus’s signs):
- Rubor — Redness (vasodilation)
- Tumor — Swelling (edema and cellular infiltration)
- Calor — Heat (increased blood flow)
- Dolor — Pain (sensation from chemical mediators)
- Functio laesa — Loss of function (added by Galen)
Two Types of Inflammation:
Acute Inflammation: Rapid onset (seconds to minutes), short duration (hours to days)
- Features: Vasodilation, increased vascular permeability, neutrophil emigration, exudate formation
- Exudate: High protein, high cellular content — indicates significant tissue injury
- Transudate: Low protein, low cellular content — caused by hydrostatic/oncotic pressure changes
Chronic Inflammation: Longer duration (weeks to months), characterized by:
- Lymphocyte and macrophage infiltration
- Fibrosis and angiogenesis
- Granuloma formation
Chemical Mediators of Inflammation:
| Mediator | Source | Effect |
|---|---|---|
| Histamine | Mast cells, basophils, platelets | Vasodilation, increased permeability |
| Prostaglandins | Arachidonic acid (COX pathway) | Pain, fever, vasodilation |
| Leukotrienes | Arachidonic acid (LOX pathway) | Bronchoconstriction, vascular permeability |
| Cytokines (TNF-α, IL-1) | Macrophages | Fever, systemic acute-phase response |
| Complement (C3a, C5a) | Liver (hepatocytes) | Anaphylatoxins, chemotaxis |
| Kinins (bradykinin) | Plasma | Pain, vasodilation, permeability |
⚡ Exam Tip for INI CET (AIIMS PG): NSAIDs block COX pathway → reduce prostaglandins → reduce pain, fever, and inflammation. This is why they’re called anti-inflammatory.
Outcomes of Inflammation:
- Complete resolution (ideal outcome)
- Healing by fibrosis (scarring)
- Chronic inflammation
- Suppuration (abscess formation)
- Progression to necrosis