Why does severe hypotension follow rapid intravenous administration of a large dose of allergen to a highly sensitized individual?

💡 Explanation

Severe hypotension occurs because widespread mast cell degranulation releases histamine and other mediators, causing vasodilation and increased vascular permeability, therefore blood pressure drops. Rather than lymphatic reabsorption or compensatory heart rate increases reversing this process, the vasodilation overwhelms compensatory mechanisms.

• If the liver's urea cycle malfunctions due to genetic enzyme deficiency, which consequence follows for the patient?
• If an influenza vaccine induces a weak initial antibody response, which process must improve to enhance long-term immunity following a booster?
• Why does a nerve impulse diminish beyond a synapse when neurotransmitter reuptake is highly effective?
• Why does prolonged use of certain antidepressants targeting serotonin reuptake eventually lead to a diminished effect on mood elevation?
• Which adaptation occurs when bone growth obstructs ossicles-oval window interface?
• What distinguishes proteasomal degradation from chaperone-mediated autophagy in intracellular protein clearance?