What does increased capillary permeability result from during an anaphylactic reaction?

Increased capillary permeability during an anaphylactic reaction is primarily the result of the release of histamine. Histamine is a chemical mediator that plays a crucial role in inflammatory responses and allergic reactions. When an allergen triggers an anaphylactic response, mast cells and basophils release large amounts of histamine into the bloodstream.

The release of histamine results in several physiological changes, including vasodilation and increased permeability of capillaries. This increased permeability allows fluids and immune components to leak out of the capillaries and into the surrounding tissues, leading to swelling, hives, and potentially a significant drop in blood pressure due to fluid loss from the vascular system.

This mechanism is essential for the body’s response to allergens, as it facilitates increased blood flow and immune cell access to the site of allergen exposure, but in anaphylaxis, it occurs excessively and leads to severe symptoms. Understanding this process is vital for emergency responders since managing anaphylactic reactions effectively requires addressing the effects of histamine and the resulting capillary permeability.

Other options are related to different physiological responses but do not directly cause increased capillary permeability in the context of anaphylaxis.