Inflammation and Repair Practice Questions

Q: Which of the following is not a vasodilator?

Leukotriene C4. ### Explanation The correct answer is **Leukotriene C4 (LTC4)**. The question tests your knowledge of the vascular effects of various eicosanoids (derivatives of arachidonic acid). **1. Why Leukotriene C4 is the correct answer:** Leukotrienes C4, D4, and E4 (collectively known as cysteinyl leukotrienes) are potent **vasoconstrictors**. They are primarily produced by mast cells and basophils. In addition to vasoconstriction, they cause intense bronchoconstriction and increase vascular permeability (leading to edema), making them key mediators in the pathogenesis of bronchial asthma and anaphylaxis. **2. Why the other options are incorrect:** * **Prostacyclin (PGI2):** Produced by vascular endothelium, it is a potent **vasodilator** and the most powerful endogenous inhibitor of platelet aggregation. * **Lipoxin (LXA4/LXB4):** These are anti-inflammatory mediators. Lipoxin A4 specifically induces **vasodilation** and inhibits neutrophil chemotaxis, acting as a "stop signal" for inflammation. * **Prostaglandin E2 (PGE2):** This is a major mediator of inflammation that causes **vasodilation** (hyperemia) and sensitizes nerve endings to pain (hyperalgesia). **3. NEET-PG High-Yield Clinical Pearls:** * **LTC4, LTD4, LTE4:** Known as the "Slow Reacting Substance of Anaphylaxis" (SRS-A). * **LTB4:** A potent chemotactic agent for neutrophils (Remember: **B**4 for "**B**e there" – attracts cells). * **PGI2 vs. Thromboxane A2 (TXA2):** They have opposing effects. PGI2 (Endothelium) = Vasodilation + Anti-aggregation; TXA2 (Platelets) = Vasoconstriction + Pro-aggregation. * **Aspirin-induced Asthma:** Caused by the shunting of arachidonic acid toward the lipoxygenase pathway (increasing leukotrienes) when the COX pathway is blocked.

Q: Which one of the listed receptors on leukocytes binds to pathogen-associated molecular patterns and mediates immune response to bacterial lipopolysaccharide?

Toll-like receptor. The correct answer is **Toll-like receptor (TLR)**. This question tests the fundamental concepts of innate immunity and Pattern Recognition Receptors (PRRs). **1. Why Toll-like receptor is correct:** Leukocytes (macrophages, dendritic cells, etc.) express PRRs that recognize highly conserved microbial structures known as **Pathogen-Associated Molecular Patterns (PAMPs)** [2]. Toll-like receptors are the most well-characterized PRRs [1]. Specifically, **TLR-4** is the primary receptor that recognizes and binds to **Lipopolysaccharide (LPS)**, a major component of the outer membrane of Gram-negative bacteria [1]. This binding triggers a signaling cascade (via NF-κB) leading to the production of pro-inflammatory cytokines [4]. **2. Why other options are incorrect:** * **Cytokine receptor:** These bind to signaling molecules (like Interleukins or Interferons) produced by the host's own immune cells to coordinate a response, rather than directly recognizing microbial PAMPs. * **G protein-coupled receptor (GPCR):** While some GPCRs on leukocytes (like CXCR1) are involved in chemotaxis (moving toward bacterial peptides like fMLP), they are not the primary mediators for LPS-induced immune activation [3]. * **Mannose receptor:** This is a C-type lectin receptor that recognizes terminal mannose and fucose residues on microbial sugar chains. While it is a PRR, it is primarily involved in phagocytosis rather than the specific inflammatory response to LPS. **High-Yield Clinical Pearls for NEET-PG:** * **TLR-4:** Recognizes LPS (Gram-negative bacteria) [1]. * **TLR-2:** Recognizes Peptidoglycan and Lipoteichoic acid (Gram-positive bacteria). * **TLR-3, 7, 8:** Recognize viral RNA (Double-stranded/Single-stranded). * **TLR-5:** Recognizes Flagellin [1]. * **TLR-9:** Recognizes unmethylated CpG DNA (Bacterial/Viral) [1]. * **Clinical Correlation:** Overactivation of TLR-4 by LPS is a key driver in the pathogenesis of **Septic Shock** [1].

Question 1

Cytokines are secreted in sepsis and Systemic Inflammatory Response Syndrome (SIRS) by which of the following?

Accepted Answer

Neutrophils

Answer

Adrenal gland

Answer

Platelets

Answer

Collecting duct

Question 2

A patient presents with a large wound to his right forearm that is the result of a chain saw accident. The wound is filled with granulation tissue, which is composed of proliferating fibroblasts and proliferating new blood vessels (angiogenesis). Which growth factor is capable of inducing all the steps necessary for angiogenesis?

Accepted Answer

Basic fibroblast growth factor (FGF)

Answer

Epidermal growth factor (EGF)

Answer

Transforming growth factor a (TGF-a)

Answer

Transforming growth factor b (TGF-b)

Question 3

Which of the following is not a vasodilator?

Accepted Answer

Leukotriene C4

Answer

Prostacyclin (PGI2)

Answer

Lipoxin

Answer

Prostaglandin E2 (PGE2)

Question 4

Which mediator of inflammation does NOT cause fever?

Accepted Answer

Nitric Oxide

Answer

IL-1

Answer

TNF-a

Answer

Prostaglandin

Question 5

Which one of the listed receptors on leukocytes binds to pathogen-associated molecular patterns and mediates immune response to bacterial lipopolysaccharide?

Accepted Answer

Toll-like receptor

Answer

Cytokine receptor

Answer

G protein coupled receptor

Answer

Mannose receptor

Question 6

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 7

Localized idiopathic fibrosis is seen in all of the following conditions except?

Accepted Answer

Hypertrophic scar

Answer

Riedel's struma

Answer

Sclerosing cholangitis

Answer

Panniculitis

Question 8

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

Accepted Answer

Eosinophils

Answer

Lymphocytes

Answer

Neutrophils

Answer

Basophils

Question 9

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

Accepted Answer

Selectin

Answer

ICAM

Answer

CD31

Answer

VCAM

Question 10

All of the following mediators of acute inflammation are derived from cells except?

Accepted Answer

Kinins

Answer

Cytokines

Answer

Histamine

Answer

Leukotrienes

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

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