Infection & Inflammation (Foundation II) Module — 3rd Year MBBS

AIM CONCEPT INTEGRATION

3rd Year MBBS
Infection and Inflammation

Acute Inflammation: Recognition, Vascular and Cellular Responses

Connect recognition of injury or microbes with vascular change, leukocyte recruitment and removal of the offending stimulus for rapid revision.

1. THE TOPIC IN ONE CONNECTED FLOW

Acute inflammation begins when tissue cells recognize microbes or tissue damage. This triggers mediator release, vascular changes and recruitment of leukocytes. Neutrophils then reach the affected tissue, follow chemical signals, engulf the harmful material and help remove it. The whole response is therefore one coordinated protective sequence.

Harmful Stimulus

Infection, tissue necrosis, foreign body or immune injury

→

Recognition

PAMPs or DAMPs bind pattern-recognition receptors

→

Mediator Release

Activated inflammatory cells signal local vessels

→

Vascular Response

Vasodilation + increased permeability + exudation

→

Stasis & Recruitment

Margination → rolling → adhesion → transmigration

→

Chemotaxis

Leukocytes move toward the inflammatory focus

→

Phagocytosis & Removal

Recognition → engulfment → intracellular killing

2. KEY CLINICAL CONNECTIONS

Redness, Warmth and Swelling

Arteriolar vasodilation → increased local blood flow → redness and warmth.

Increased endothelial permeability → protein-rich exudate → tissue edema and swelling.

Leukocyte Recruitment

Fluid loss from vessels → hemoconcentration and stasis → leukocyte margination.

Selectins → rolling → integrins → firm adhesion → transmigration → chemotaxis.

Cell Pattern and Function

Early acute bacterial inflammation → neutrophil recruitment → phagocytosis and microbial killing.

Later response → monocytes enter tissue → macrophages remove debris and support repair.

3. AIM HIGH-YIELD INTEGRATION REVIEW

⭐ PAMP or DAMP → PRR activation

Microbial or tissue-damage signals activate innate inflammatory cells and initiate mediator release.

Vasodilation → hyperemia

Increased local blood flow explains the redness and warmth of acute inflammation.

Increased permeability → exudate

Protein-rich fluid leaves vessels and produces inflammatory edema.

⭐ Stasis → margination

Loss of plasma slows flow and moves leukocytes toward the endothelial surface.

⭐ Selectins → rolling; integrins → adhesion

This is the key molecular distinction in the leukocyte recruitment cascade.

Transmigration → chemotaxis

After crossing post-capillary venules, leukocytes follow chemical gradients toward the injury.

Opsonization → efficient phagocytosis

Coated microbes bind phagocytes more efficiently, allowing engulfment and intracellular killing.

Leukocyte pattern → likely inflammatory setting

Neutrophilia suggests acute bacterial inflammation; eosinophilia favors allergy or parasites; monocytosis may accompany prolonged inflammation.

AIM Exam Trap

Do not confuse rolling with firm adhesion: rolling is mainly selectin-mediated, whereas firm adhesion is mainly integrin-mediated.

Acute Inflammation: Recognition, Vascular and Cellular Responses

1. THE TOPIC IN ONE CONNECTED FLOW

2. KEY CLINICAL CONNECTIONS

3. AIM HIGH-YIELD INTEGRATION REVIEW

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