Inflammation and Repair Practice Questions

Q: Which of the following leukotrienes aids in leukocyte adhesion?

LTB4. **Explanation:** Leukotrienes are potent inflammatory mediators derived from arachidonic acid via the **5-lipoxygenase pathway**. **Why LTB4 is correct:** **LTB4 (Leukotriene B4)** is primarily a potent **chemoattractant** and activator of neutrophils [1]. Its role in leukocyte adhesion is critical; it induces the expression of **integrins** (specifically CD11/CD18) on the surface of leukocytes, which allows them to bind firmly to ICAM-1 on the vascular endothelium [1]. Beyond adhesion, LTB4 also stimulates chemotaxis, the release of lysosomal enzymes, and the generation of reactive oxygen species (ROS) [1]. **Why the other options are incorrect:** * **LTC4, LTD4, and LTE4:** These are collectively known as **cysteinyl leukotrienes** (or the "slow-reacting substance of anaphylaxis"). Their primary functions are related to smooth muscle contraction and vascular permeability [1]. They cause intense **bronchospasm** (important in asthma pathogenesis) and increased **venular permeability** (leading to edema), but they do not play a direct role in leukocyte adhesion or chemotaxis [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Chemotactic Agents "Big Four":** Remember the mnemonic **"C-B-I-L"** for the most important chemoattractants: **C**5a, **B**4 (LTB4), **I**L-8, and **L**PS (Bacterial products). * **Aspirin-Exacerbated Respiratory Disease (AERD):** Inhibiting COX-1 shunts arachidonic acid toward the lipoxygenase pathway, increasing leukotriene production, which leads to bronchospasm. * **Pharmacology Link:** **Zileuton** inhibits 5-lipoxygenase (preventing LTB4/C4/D4/E4 synthesis), while **Montelukast** blocks the receptors for cysteinyl leukotrienes (LTC4/D4/E4). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 95-96.

Q: Complete wound strength, in terms of collagen recovery, is regained in what period of time?

Never regained. **Explanation:** The correct answer is **A. Never regained**. [1] The underlying medical concept is that tissue repair in humans occurs via two processes: **regeneration** (replacement by the same cell type) and **healing by fibrosis/scarring**. Skin wounds heal primarily through scarring. While a scar provides structural integrity, it is a fibrous patch rather than a perfect reconstruction of the original dermis. The timeline of wound strength recovery is as follows: * **At 1 week:** Approximately 10% of the strength of unwounded skin. [1] * **At 3 months:** Strength increases rapidly to about 70–80%. [1] * **Long-term:** Wound strength plateaus at roughly **70–80%** of the original tensile strength. It never reaches 100% because the collagen fibers in a scar are thinner and more disorganized compared to the basket-weave pattern of normal dermis. [1] **Why incorrect options are wrong:** * **B, C, and D:** These options suggest that given enough time (1 month to 1 year), the tissue will eventually return to its baseline strength. However, the remodeling phase of wound healing involves a balance of collagen synthesis by myofibroblasts and degradation by Matrix Metalloproteinases (MMPs). This process improves strength significantly but never achieves full recovery. [1] **High-Yield NEET-PG Pearls:** * **Type III Collagen** is synthesized first during the proliferative phase (granulation tissue). * **Type I Collagen** eventually replaces Type III during the remodeling phase to provide more strength. * **Vitamin C** is a critical cofactor for the hydroxylation of proline and lysine residues; deficiency leads to poor wound healing (Scurvy). * **Zinc deficiency** also impairs wound healing as it is a cofactor for MMPs involved in remodeling. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 119-121.

Question 1

Which of the following cells are normally in the G0 stage of the cell cycle, hence not proliferating, but are capable of dividing in response to injury?

Accepted Answer

Parenchyma of most solid organs

Answer

Transitional epithelium of the urinary tract

Answer

Neurons

Answer

Skeletal muscles

Question 2

Parasitic inflammation typically shows a predominance of which type of inflammatory cell?

Accepted Answer

Eosinophils

Answer

Lymphocytes

Answer

Neutrophils

Answer

Basophils

Question 3

What is the main cell responsible for scar contraction?

Accepted Answer

Myofibroblast

Answer

Fibroblast

Answer

Epithelial cell

Answer

Elastin

Question 4

Sialyl-Lewis X is linked to which of the following?

Accepted Answer

Selectin

Answer

ICAM

Answer

CD31

Answer

VCAM

Question 5

The complex process of leukocyte extravasation includes all EXCEPT?

Accepted Answer

Phagocytosis

Answer

Rolling

Answer

Adhesion

Answer

Migration

Question 6

When sutures are removed from an incisional surgical wound at the end of one week, what is the approximate wound strength compared to unwounded skin?

Accepted Answer

10%

Answer

50%

Answer

80%

Answer

1%

Question 7

Which of the following leukotrienes aids in leukocyte adhesion?

Accepted Answer

LTB4

Answer

LTD4

Answer

LTE4

Answer

LTC4

Question 8

Which of the following is NOT a known effect of transforming growth factor?

Accepted Answer

Activates macrophages

Answer

Promotes fibroblast proliferation

Answer

Promotes endothelial cell proliferation

Answer

Induces chemotaxis of fibroblasts

Question 9

Which cell type releases the vasoactive amine that causes vasodilation during inflammation?

Accepted Answer

Mast cells

Answer

Plasma cells

Answer

Lymphocytes

Answer

Monocytes

Question 10

Complete wound strength, in terms of collagen recovery, is regained in what period of time?

Accepted Answer

Never regained

Answer

1 month

Answer

6 months

Answer

1 year

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

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