Inflammation and Repair Practice Questions

Q: Which of the following statements is NOT true about cytokines?

Cytokines participate in intrinsic enzymatic reactions.. Cytokines are low-molecular-weight soluble proteins or **polypeptides** that act as mediators of inflammation and immune responses [1]. **Why Option D is the Correct Answer (The False Statement):** Cytokines do **not** possess intrinsic enzymatic activity. Unlike enzymes, they function by binding to specific high-affinity cell surface receptors. This binding triggers intracellular signaling cascades (most commonly the **JAK-STAT pathway**) to alter gene expression. They act as signaling molecules rather than catalysts for biochemical reactions. **Analysis of Other Options:** * **Option A:** Cytokines are indeed **polypeptides** produced by various cells, primarily activated lymphocytes, macrophages, and dendritic cells [1]. * **Option B:** They exhibit multiple modes of action: **Autocrine** (acting on the cell that secreted them), **Paracrine** (acting on adjacent cells), and occasionally **Endocrine** (systemic effects, e.g., IL-1 and TNF causing fever). * **Option C:** A specific subset of cytokines called **Chemokines** (e.g., IL-8) is responsible for stimulating leukocyte chemotaxis and controlling leukocyte movement from the blood into tissues [1]. **High-Yield NEET-PG Pearls:** * **TNF and IL-1:** The "master cytokines" of acute inflammation; they induce the expression of adhesion molecules (E-selectin) on endothelium. * **JAK-STAT Pathway:** The most common signaling pathway for cytokine receptors; mutations in this pathway are linked to myeloproliferative neoplasms. * **Pleiotropy:** The ability of one cytokine to act on multiple cell types (e.g., IL-4 acting on B-cells, T-cells, and mast cells). * **Redundancy:** Multiple cytokines exerting the same functional effect [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 93-99.

Q: Pain during inflammation is mediated by which of the following substances?

Bradykinin. ### Explanation **Correct Answer: C. Bradykinin** The cardinal signs of inflammation (Rubor, Calor, Tumor, Dolor, and Functio laesa) are mediated by specific chemical compounds. **Pain (Dolor)** is primarily mediated by **Bradykinin** and **Prostaglandins (specifically PGE2)** [1]. Bradykinin is a potent inflammatory mediator derived from the kinin system. It acts on B1 and B2 receptors to sensitize nociceptors (pain receptors) and cause direct stimulation of nerve endings [1]. While Prostaglandins do not cause pain directly, they lower the threshold for pain (hyperalgesia), making the effect of Bradykinin more intense [1]. --- ### Analysis of Incorrect Options: * **A. Nitric Oxide (NO):** Primarily responsible for **vasodilation** (Rubor and Calor) and has some bactericidal activity. It also helps in reducing the inflammatory response by inhibiting platelet aggregation [1]. * **B. Leukotriene B4 (LTB4):** This is a potent **chemotactic agent** [1]. Its primary role is the recruitment and activation of neutrophils to the site of injury. It does not directly mediate pain. * **C. Chemokines:** These are small proteins (like IL-8) that act as **chemoattractants** for specific types of white blood cells [1]. They guide the migration of cells but are not primary mediators of the pain response. --- ### NEET-PG High-Yield Pearls: * **Mediators of Pain:** Bradykinin and PGE2 [1]. * **Mediators of Fever:** IL-1, TNF, and PGE2 (acting on the hypothalamus) [1]. * **Mediators of Vasodilation:** Histamine, Prostaglandins, and Nitric Oxide [1]. * **Mediators of Increased Vascular Permeability:** Histamine, C3a, C5a, and Leukotrienes (LTC4, LTD4, LTE4) [1]. * **Chemotaxis "Big Four":** LTB4, C5a, IL-8, and Bacterial products (N-formyl methionine) [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 100-101.

Q: In acute inflammation, pain is primarily mediated by which of the following substances?

Bradykinin. **Explanation:** In the process of acute inflammation, the cardinal sign of **Pain (Dolor)** is primarily mediated by **Bradykinin** and **Prostaglandins (PGE2)** [1]. **1. Why Bradykinin is correct:** Bradykinin is a potent inflammatory mediator derived from the kinin system (activated by Hageman factor/Factor XII). It acts directly on nociceptors (pain receptors) in the peripheral nervous system, increasing their sensitivity [1]. While Prostaglandins also cause pain, they primarily act by "sensitizing" the nerve endings to other mediators like Bradykinin [1]. Therefore, Bradykinin is considered the direct chemical mediator of the pain response. **2. Analysis of Incorrect Options:** * **A. Serotonin:** Primarily released by platelets; its main roles are vasoconstriction and acting as a neurotransmitter [1]. It does not play a primary role in the pain of acute inflammation. * **B. Histamine:** Released by mast cells, it is the chief mediator of **vasodilation** and **increased vascular permeability** (leading to redness and swelling/edema), but it does not directly mediate pain [1]. * **C. Cytokines:** While TNF and IL-1 are crucial for the systemic acute phase response (fever, leucocytosis), they do not directly stimulate pain receptors [1]. **3. NEET-PG High-Yield Pearls:** * **Mediators of Vasodilation:** Histamine and Nitric Oxide (NO). * **Mediators of Increased Permeability:** Histamine, Bradykinin, and Leukotrienes (C4, D4, E4) [1]. * **Mediators of Fever:** IL-1, TNF, and Prostaglandins (PGE2) [1]. * **Mediators of Chemotaxis:** C5a, LTB4, and IL-8 [1]. * **Pain Duo:** Remember **Bradykinin** (direct) and **PGE2** (sensitizer) [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 100-101.

Question 1

Which of the following is an anti-inflammatory mediator?

Accepted Answer

Interleukin 4

Answer

Interleukin 1

Answer

Interleukin 6

Answer

TNF-Alpha

Question 2

Which of the following statements is NOT true about cytokines?

Accepted Answer

Cytokines participate in intrinsic enzymatic reactions.

Answer

Cytokines are polypeptides.

Answer

Cytokines can exert autocrine and paracrine effects.

Answer

Cytokines are involved in leukocytic movements.

Question 3

Pain during inflammation is mediated by which of the following substances?

Accepted Answer

Bradykinin

Answer

Nitric oxide

Answer

Leukotriene B4

Answer

Chemokines

Question 4

Which of the following is NOT a role of histamine in acute inflammation?

Accepted Answer

Causes vasoconstriction

Answer

Mediates increase in vascular permeability

Answer

Mediates chemotaxis

Answer

Facilitates release of pain-causing substances

Question 5

The epithelioid cell is a modified-

Accepted Answer

Macrophage

Answer

Lymphocyte

Answer

Mast cell

Answer

Eosinophil

Question 6

During internal injury, leukocytes are recruited by which of the following?

Accepted Answer

IL-1

Answer

Selectin

Answer

Integrin

Answer

IL-6

Question 7

What are the most characteristic features of acute inflammation?

Accepted Answer

Vasodilation and increased vascular permeability

Answer

Vasoconstriction

Answer

Vascular stasis

Answer

Margination of leukocytes

Question 8

What is the most important inflammatory mediator?

Accepted Answer

TNF

Answer

IL2

Answer

Interferon

Answer

PAF

Question 9

Eosinophilia is typically found in infections caused by which of the following organisms?

Accepted Answer

Strongyloides

Answer

Cryptococcus

Answer

Human Papillomavirus (HPV)

Answer

Typhoid

Question 10

In acute inflammation, pain is primarily mediated by which of the following substances?

Accepted Answer

Bradykinin

Answer

Serotonin

Answer

Histamine

Answer

Cytokines

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

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