Arrange the steps in cellular changes in inflammation in the sequence: 1. Chemotaxis 2. Diapedesis3. Margination4. Respiratory burst 5. Phagocytosis
**Core Concept**
The cellular changes in inflammation involve a series of complex interactions between various cell types, including neutrophils, macrophages, and endothelial cells. The sequence of events is crucial for the effective resolution of inflammation and tissue repair.
**Why the Correct Answer is Right**
The correct sequence of cellular changes in inflammation is as follows:
1. **Margination**: This is the initial step where leukocytes, particularly neutrophils, marginate or move to the periphery of blood vessels, facilitated by the expression of adhesion molecules on the surface of endothelial cells.
2. **Chemotaxis**: Once the leukocytes have marginated, they undergo chemotaxis, a process where they are attracted to the site of inflammation by chemokines, which are secreted by resident cells and endothelial cells.
3. **Diapedesis**: As the leukocytes reach the site of inflammation, they undergo diapedesis, a process where they cross the endothelial layer and migrate into the tissue space.
4. **Respiratory burst**: Upon entering the tissue space, leukocytes undergo a respiratory burst, a metabolic process where they generate reactive oxygen species (ROS) to kill ingested microorganisms.
5. **Phagocytosis**: Finally, leukocytes engage in phagocytosis, the process of engulfing and ingesting foreign particles, including microorganisms, to eliminate them from the body.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because margination occurs before chemotaxis, allowing leukocytes to position themselves for chemotactic migration.
**Option B:** This option is incorrect because diapedesis occurs after chemotaxis, as leukocytes cross the endothelial layer to reach the site of inflammation.
**Option C:** This option is incorrect because respiratory burst occurs after diapedesis, as leukocytes generate ROS to kill ingested microorganisms.
**Option D:** This option is incorrect because phagocytosis occurs after respiratory burst, as leukocytes engulf and ingest foreign particles.
**Clinical Pearl / High-Yield Fact**
A key aspect of inflammation is the recruitment of leukocytes to the site of injury or infection. Understanding the sequence of cellular changes in inflammation is crucial for developing effective treatments for inflammatory disorders.
**Correct Answer:** C. Margination, Chemotaxis, Diapedesis, Respiratory burst, Phagocytosis