Question

question 52
the heat and redness that characterize inflammation are caused by ______.
a the release of signaling molecules that increase blood flow to infected area
b the initial invasion of host tissue by pathogens
c the ingestion of pathogens by white blood cells
d clotting reactions
e the influx of fluids from leaky blood vessels to infected tissues

Explanation:

To solve this, we analyze each option:

• Option A: Signaling molecules (like histamine) released during inflammation cause blood vessels to dilate, increasing blood flow. This increased blood flow leads to heat (from more blood) and redness (from dilated vessels), matching the symptoms.
• Option B: Initial pathogen invasion triggers inflammation but isn’t the direct cause of heat/redness.
• Option C: Phagocytosis (ingestion by WBCs) is part of the immune response, not the cause of heat/redness.
• Option D: Clotting reactions stop bleeding, not cause inflammation symptoms.
• Option E: Fluid influx causes swelling (edema), not heat/redness.

Answer:

A. the release of signaling molecules that increase blood flow to infected area