Question

Which of the following protein causes the dilation of blood vessels?

• A. Histamine
• B. Pyrogens
• C. Interferon
• D. None of these

Answer 1

Answer:

A. Histamine

• Mast cells are large cells with densely granular cytoplasm that are found in connective tissues.

• Mast cell granules contain mediators of inflammation, such as histamine, serotonin, and various chemotactic factors (substances that attract white blood cells to the area of infection).

• Histamine released from ruptured mast cells causes marked dilation of all the arteries so that a large amount of fluid is passed from the blood to the tissues and there is a drastic fall in blood pressure.