Question

multiple choice question
when microorganisms invade tissues, leukocytes release chemicals that ______, producing swelling that delays the spread of pathogens to other areas of the body

• make small blood vessels more permeable
• act as water channels
• make large blood vessels less permeable

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Explanation:

When microorganisms invade tissues, leukocytes release chemicals called cytokines and histamines. These chemicals make small blood vessels (capillaries) more permeable. This increased permeability allows fluid, immune - cells, and nutrients to move from the blood into the tissues, causing swelling (edema) which helps contain the pathogens and prevent their spread. Water channels are not the main function of these chemicals in this context, and the action is on small, not large, blood vessels to increase permeability.

Answer:

A. make small blood vessels more permeable