Which one of the following substance is released during inflammatory process when platelets are activated?

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Explanation

Serotonin (5-hydroxytryptamine) is a key vasoactive amine stored in the dense granules of platelets.
Upon activation at a site of injury or inflammation, platelets undergo degranulation, releasing their contents, including serotonin.
Released serotonin acts as a potent vasoconstrictor, which helps in hemostasis (stopping bleeding), and also increases vascular permeability.

Option A: Histamine is not the primary substance released by activated platelets. Its main sources are mast cells and basophils.
Option B: Heparin is an anticoagulant, not a primary inflammatory mediator released by platelets. It is released from mast cells and basophils.
Option D: Bradykinin is not stored in and released from cells. It is generated from plasma proteins (kininogens) during the inflammatory response.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Chemical Mediators of Inflammation as background academic context rather than a clinical decision trigger.
Understanding the source of inflammatory mediators is crucial for pharmacology. For example, knowing that platelets release serotonin helps explain why Selective Serotonin Reuptake Inhibitors (SSRIs), which affect serotonin levels, can increase bleeding risk by impairing platelet function.
In conditions like thrombosis, the release of serotonin from activated platelets contributes to the vasoconstriction and platelet aggregation that form a clot.
What if the question asked about a mediator causing pain and vasodilation? Then Bradykinin would be a strong candidate, as it is a potent pain-producing substance (algesic) and vasodilator formed during inflammation.

How to Approach the Question

First, identify the key terms in the question: 'substance released', 'inflammatory process', and 'platelets activated'. The most critical clue is 'platelets'.
Next, recall the different cells involved in inflammation (platelets, mast cells, basophils, neutrophils) and the primary chemical mediators they store and release.
Consider each option: Histamine (mostly mast cells), Heparin (mast cells), Serotonin (platelets), and Bradykinin (plasma-derived).
Differentiate between mediators that are pre-formed and stored in cells (like histamine and serotonin) and those that are synthesized or generated from precursors during the response (like bradykinin and prostaglandins).
Based on the direct link between platelets and serotonin storage, select serotonin as the correct answer.

Concept Tested & Keywords

Q0lbnprTfHtkHmt--mTEWT

E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed pp. 95-97, 101-103

Practise the full RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Attempt every question from this paper in a timed mock, then review the full solution for each one.