THE PROCESS OF YAWNING

            Yawning is a stereotypical reflex characterized by a single deep inhalation (with the mouth open) and stretching of muscles. At the first time, one might see yawning as a silly phenomenon to spend time studying because it happens when we are tired. However, it is more complicated than that. Yawning is not only a sign of exhaustion but also a much more general sign of changing conditions within the body.  

            Yawning begins with, when we are tired. It makes the brain saturated. Saturation of the brain stimulates brain neurons to work harder. It makes the brain exhaustion. Therefore, the tiredness on brain giving the brain raises stress. Stress brain makes the blood vessels increased the amounts of carbon dioxide. It becomes in need of the influx of oxygen to reduce carbon dioxide toxicity. It happens in paraventricular nucleus (PVN) of hypothalamus of the brain. It appears that the PVN of hypothalamus is the yawning center of the brain.

            The specific neurons in the PVN require production of nitric oxide. Once stimulated, the cells of the PVN activate cells of the brain stem (hippocampus). Cell activation in the central part of the brain needs a huge energy. This makes the brain work harder. Hard work in the brain makes the temperature become overheated. To prevent damage in the brain, the brain sends signal to the body. The body responses by send signals back to the brain. Then the brain will respond by taking oxygen to the lungs. The last Lungs respond by taking oxygen outside the body by yawning with make the mouth open.

            Yawning process happens when the brain being overheated. So, it is not only a sign of tiredness. Yawning is an important process to cool the brain so, it prevents from brain damage.

BY LAILATUL KHIKMAH :D
this is process essay