最近,英国两位神经学家提出打呵欠可能是一种脑干反射。从生理角度上来讲,打呵欠本身是人体的一种保护性反应。在打呵欠时通过张口深吸气,使脑内压下降,静脉血大量回流入心脏,以此增加心脏的输出量;同时脑腔相对增大,气道舒张,吸进的氧气增加,二氧化碳加快 Recently, two British neurologists proposed yawning may be a brainstem reflex. Physiologically speaking, yawning itself is a protective reaction in the body. In the yawning deep breath through the mouth, the brain pressure drop, a large number of venous return to the heart, in order to increase the output of the heart; the same time, relatively increased brain cavity, airway dilatation, inhaled oxygen increased, carbon dioxide accelerated