Blood disease is a kind of hysteria, that is, the overreaction of consciousness and body caused by touching or seeing or smelling blood. Consciously have panic, palpitation, dizziness and other reactions. Physiologically and physically, it is characterized by increased blood pressure, increased heart rate, nausea and weakness of limbs.
In fact, syncope stems from the conscious activity of the cerebral cortex. The brain issues instructions to promote the secretion of related hormones and produce physiological and physical reactions.