photo-1784521781397.jpg

+2 more

Make this note worth time , its time consuming

analyse_media

Here is a clean, well-structured, exam-ready note based on your photos — covering leukocyte recruitment, activation, phagocytosis, and chemical mediators:

🔬 Inflammation: Leukocyte Recruitment & Activation

Steps in Leukocyte Extravasation (Fig. 3.3)

In the Vascular Lumen:

Step	What Happens
1. Margination	Blood flow slows (stasis) → leukocytes (mainly neutrophils) move to peripheral column and accumulate along the endothelial surface
2. Rolling	Marginated leukocytes attach weakly to the endothelium → detach and bind again → causes rolling movement along the endothelial surface
3. Adhesion	Endothelium gets activated → leukocytes bind more firmly

Across the Vessel Wall:

Step	What Happens
Transmigration / Diapedesis	Leukocytes squeeze through the vessel wall via intercellular junctions between endothelial cells
Migration across basement membrane	Leukocytes pierce the basement membrane of the vessel
Chemotaxis	Migration of leukocytes toward the inflammatory stimulus in the direction of the chemoattractant gradient

Chemoattractants = chemicals that attract leukocytes to site of injury; can be exogenous (e.g. bacterial products) or endogenous

Accumulation of Leukocytes

Leukocytes accumulate at sites of infection and injury

Leukocyte Activation

Trigger: Recognition of microbes or dead cells by leukocytes → initiates several responses = Leukocyte Activation

Most important feature: Phagocytosis + Intracellular Killing

Phagocytosis & Clearance of the Offending Agent

Leukocytes recognize, internalize, and digest foreign material, microorganisms, or cellular debris.

3 Steps of Phagocytosis:

1. Recognition & Attachment

Phagocytic cells recognize components of microbes and necrotic cells

2. Engulfment

Cytoplasm of leukocyte forms pseudopods surrounding the particle
Forms a vesicle = Phagosome

3. Killing & Degradation of Ingested Material

Phagolysosome forms: membrane of phagosome fuses with lysosome
Lysosomal granules discharge into the phagolysosome
Occurs within neutrophils and macrophages

Microbial Killing Mechanisms

Reactive Oxygen Species (ROS):

Generated by free radicals
ROS generated by H₂O₂ are important microbicidal agents
MPO-halide system (myeloperoxidase in neutrophils) = most efficient bactericidal system
Superoxide anion (O₂⁻) = powerful ROS; neutrophils can convert weak ROS → stronger ROS

General Features of Chemical Mediators

Feature	Detail
Source	From cells OR from plasma proteins
Chemical mediators have high activity	Act locally; mostly short-lived
Short-lived	Most have brief lifespan
Main mediators listed in Table 3.3

Cell-Derived Mediators:

Vasoactive Amines:

Histamine
Serotonin

Quick Recall: Sequence Summary

Stasis → Margination → Rolling → Adhesion
→ Transmigration (Diapedesis) → Chemotaxis
→ Leukocyte Activation → Phagocytosis
→ Phagosome + Lysosome = Phagolysosome
→ Killing by ROS / MPO-halide system

This gives you everything from the 3 pages in one clean read-through. Let me know if you want flashcards, a diagram, or a MCQ quiz made from this content!

This is a shared conversation. Sign in to Orris to start your own chat.