Yawn and shed tears is a situation that many people have experienced. What's going on? Is it a normal physiological reaction or a disease? Let's get to know each other.
1. When people yawn, their mouth is wide open. They may let their breath out of the body more in order to exhale carbon dioxide and inhale oxygen. With the action of yawning, a strong breath was exhaled from the mouth. The muscles of the cheek, tongue and throat tense and contract. At this time, the pressure of the mouth and nose increases.
2. As a result of increased nasal pressure, the nasolacrimal duct will temporarily block the excretion of tears. The 'sewer' is blocked, the tears can't flow, and more and more tears accumulate in the eyes. Will be two tears, and finally burst into tears and flow to his face.
3. When the brain temperature rises (such as just waking up or sleepy), yawning can make the maxillary sinus expand and contract like a bellows, pressing air into the brain, thus reducing the brain temperature. Therefore, yawning may be a measure taken by the brain to 'cool down'.