Question

What is the reason behind hunger or what stimulates it?

Answer 1

A major cause for feeling hungry lies in the physiology of blood circulation. Levels of different substances are generally maintained in the blood mainly by our digestive system. When the level of glucose in the blood fall, we get hunger pangs in the stomach. It also involves production of a series of proteins, that are hormones like Ghrelin. Ghrelin is secreted from certain cells in the wall of the stomach, when it is empty. Hunger contractions (hunger pangs) start to occur in the stomach due to hunger generating signals that reach the brain from the stomach due to the secretion of this hormone. It is believed that the Diencephalon in forebrain and vagus nerve (10th cranial nerve) plays an important role in carrying these signals to the brain. Hunger pangs continue up to 30- 45 minutes. Increase in ghrelin levels results in sensation of hunger and motivation to consume food.