Appetite is the physiological craving to eat food and is manifested in the form of hunger and the need to feed oneself. The need to eat is dependent on ones own internal metabolic factors, which are influenced by things like the level of physical activity and exertion. Appetite is controlled by a combination of physiological factors and mechanisms that involve the stomach, brain and other organs. The primary area of the body that controls appetite is the hypothalamus section of the brain; it is responsible for regulating and making one aware of hunger. The digestive tract (including the stomach) plays the role of a sensor in the appetite and hunger mechanism, it signals to the brain whether or not hunger has been satiated.