Biology Circulation / Transport BUMHS 2022
PMDC Verified Question 33 of 54
Histamine causes blood vessels to:
A
Dilate
B
Constrict
C
Block
D
Rupture
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Dilate
Concept:

Histamine is a primary chemical mediator in the inflammatory response and allergic reactions.

Formula:

None

Solution:

  • When released by mast cells or basophils, histamine acts on the smooth muscle of local blood vessels.


  • It causes aggressive vasodilation (widening of the vessels) and increases capillary permeability.


  • This allows more blood, immune cells, and fluid to reach the site of infection or injury, causing classic redness and swelling.


Why other options are incorrect:

  • Constrict: Histamine does the exact opposite; vasoconstriction is typically caused by epinephrine or angiotensin.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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