What is the function of feeling the sensation of hunger?

Hunger is a normal sensation that makes you want to eat.

Explanation:

Your body tells your brain that your stomach is empty. This makes your stomach growl and gives you hunger pangs. Hunger makes some people feel lightheaded or grouchy.

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what do the different brain waves do?

explanation:

brainwaves are produced by synchronised electrical pulses from masses of neurons communicating with each other. brainwaves are detected using sensors placed on the scalp. brainwave speed is measured in hertz (cycles per second) and they are divided into bands delineating slow, moderate, and fast waves.