anaphylaxis
anaphylaxis (an`ȧ*fī*lak"sis or an`ȧ*fi*lak"sis) , noun
[Greek 'ana` back, way from + fy`laxis security, protection.]
1.
(Medicine) Hypersensitivity (to a foreign antigen) resulting from prior contact with the same or a related substance.
2.
(Medicine) An immediate but transient systemic reaction to an antigenic substance to which a person has become hypersensitized; it is characterized by the contraction of smooth muscle and capillary dilation. — [Stedman]
The cascade of events is triggered by binding of the foreign antigen to immunoglobulin E and release of mediators such as histamine, bradykinin, serotonin, and slow-reacting substance from mast cells. It involves more than one organ system. The most commonly involved organs are skin, cardiovascular, respiratory and gastrointestinal systems. Anaphylaxis is manifested by a range of signs and symptoms including pruritus, urticaria, itching, dyspnea, abdominal pain and cardiovascular collapse (shock). A severe form of the reaction is called anaphylactic shock.
3.
(Med) Anaphylactic shock.