Inflammation and Repair Practice Questions

Q: In the cyclooxygenase (COX) pathway of arachidonic acid metabolism, which of the following products promotes platelet aggregation and vasoconstriction?

Thromboxane A2. The correct answer is **Thromboxane A2 (TXA2)**. Arachidonic acid is released from membrane phospholipids by phospholipase A2 [1] and metabolized via two major pathways: the Cyclooxygenase (COX) pathway and the Lipoxygenase (LOX) pathway. 1. **Why Thromboxane A2 is correct:** TXA2 is synthesized primarily in platelets via the COX pathway. It is a potent **vasoconstrictor** and a powerful **inducer of platelet aggregation** [1]. It acts in physiological antagonism to Prostacyclin (PGI2), which is a vasodilator and inhibitor of aggregation. The balance between TXA2 and PGI2 is critical for maintaining vascular homeostasis. 2. **Why other options are incorrect:** * **C5a:** This is a component of the Complement System (Anaphylatoxin). Its primary roles are chemotaxis for neutrophils and increasing vascular permeability [1]; it is not a product of the COX pathway. * **Leukotriene B4 (LTB4):** While derived from arachidonic acid, it is a product of the **Lipoxygenase (LOX) pathway**. It is a potent chemotactic agent for neutrophils but does not cause platelet aggregation [1]. * **C1 activators:** These are proteins involved in the initiation of the Classical Complement pathway, unrelated to arachidonic acid metabolism. **NEET-PG High-Yield Pearls:** * **Aspirin's Mechanism:** Low-dose aspirin irreversibly inhibits COX-1, shifting the balance toward PGI2 (antithrombotic) by inhibiting TXA2 synthesis in platelets (which cannot regenerate the enzyme) [1]. * **Chemotaxis Mnemonic:** "Big B" (**LTB4**), **C5a**, and **IL-8** are the primary "attractants" for neutrophils. * **Vasodilation:** Prostaglandins **PGI2, PGE1, PGE2, and PGD2** are primarily vasodilators [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 95-96.

Q: Which of the following is the WRONG combination regarding adhesion molecules and their corresponding CD markers?

PECAM - CD64. This question tests your knowledge of **Adhesion Molecules**, which are critical for leukocyte trafficking and the inflammatory response. In the NEET-PG exam, matching Cluster of Differentiation (CD) markers to their common names is a high-yield topic. ### **Explanation of the Correct Answer** **Option D (PECAM - CD64) is the WRONG combination.** * **PECAM-1** (Platelet Endothelial Cell Adhesion Molecule-1) is actually **CD31**. It is expressed on leukocytes and endothelial cells and is primarily responsible for **diapedesis** (transmigration of leukocytes through the endothelial junction) [1]. * **CD64** is the marker for **FcγRI**, the high-affinity receptor for IgG found on macrophages, monocytes, and neutrophils. ### **Analysis of Other Options** * **A. VCAM - CD106:** Correct. Vascular Cell Adhesion Molecule-1 (VCAM-1) is CD106. It binds to VLA-4 integrins on leukocytes and is involved in firm adhesion. * **B. ICAM - CD102:** Correct. Intercellular Adhesion Molecule-2 (ICAM-2) is CD102. It is constitutively expressed on endothelial cells. * **C. ICAM-1 - CD54:** Correct. ICAM-1 is CD54. It is upregulated by cytokines (TNF, IL-1) and is the ligand for LFA-1 (CD11a/CD18) during firm adhesion. ### **High-Yield Clinical Pearls for NEET-PG** * **Selectins (Rolling):** L-Selectin (CD62L), E-Selectin (CD62E), P-Selectin (CD62P). * **Integrins (Adhesion):** LFA-1 (CD11a/CD18) and MAC-1 (CD11b/CD18). * **LAD Type 1:** Caused by a deficiency in **CD18** (integrin β2 chain), leading to impaired firm adhesion and recurrent infections without pus formation [1]. * **LAD Type 2:** Caused by a deficiency in **Sialyl-Lewis X** (ligand for selectins), leading to impaired rolling. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 87-89.

Question 1

In the cyclooxygenase (COX) pathway of arachidonic acid metabolism, which of the following products promotes platelet aggregation and vasoconstriction?

Accepted Answer

Thromboxane A2

Answer

C5a

Answer

Leukotriene B4

Answer

C1 activators

Question 2

The healing of an extraction socket where flaps are approximated occurs by which type of intention?

Accepted Answer

Primary intention

Answer

Secondary intention

Answer

Tertiary intention

Answer

Any of the above

Question 3

VEGF is involved in all of the processes of angiogenesis except:

Accepted Answer

Enhances the production of ECM proteins

Answer

Migration and proliferation of endothelial cells

Answer

Capillary sprouting

Answer

Increased vascular permeability

Question 4

Which of the following mediators are involved in the resolution of inflammation?

Accepted Answer

TNF alpha, IL-10 and IL-1 receptor antagonist

Answer

TNF alpha, IL-1 and CRP

Answer

TNF beta, IL-6 and CRP

Answer

TNF gamma

Question 5

Pain in inflammation is mediated by?

Accepted Answer

Prostaglandins and bradykinins

Answer

Histamine and nitric oxide

Answer

Prostaglandins and interleukins

Answer

Interferons and free radicals

Question 6

Which of the following statements regarding hypertrophic scars is true?

Accepted Answer

Usually occurs across flexural areas

Answer

Does not improve with time

Answer

Overgrows its boundaries

Answer

Develops months after surgery

Question 7

ESR is a critical investigation in the diagnosis of TB. Which of the following is true about ESR in TB?

Accepted Answer

ESR is raised due to increased RBC aggregation

Answer

No change in ESR

Answer

Confirms recovery from TB

Answer

ESR is raised due to decreased RBC size

Question 8

Which of the following is the WRONG combination regarding adhesion molecules and their corresponding CD markers?

Accepted Answer

PECAM - CD64

Answer

VCAM - CD106

Answer

ICAM - CD102

Answer

ICAM1 - CD54

Question 9

All of the following are opsonins, except?

Accepted Answer

LTB4

Answer

IgG

Answer

C3b

Answer

Mannose binding lectin

Question 10

Which is the most potent chemotactic complement?

Accepted Answer

C5a

Answer

C5b

Answer

C4a

Answer

C2b

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

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