"Appetite, craving for food, is a constant and powerful stimulator of the gastric glands"

This quote by Ivan Pavlov is referring to the physiological procedure of digestion. Hunger is the desire for food, and it is an effective stimulus for the gastric glands. The stomach glands are responsible for secreting gastrointestinal juices, such as hydrochloric acid and enzymes, which are required for breaking down food into smaller molecules that can be absorbed by the body. Hunger is a natural action to cravings, and it is the body's way of informing us that it requires food. When we feel hungry, the stomach glands are stimulated to produce digestive juices, which help to break down the food we eat. This procedure is necessary for appropriate digestion and nutrient absorption. Pavlov's quote emphasizes the value of cravings in the gastrointestinal procedure, and how it is an effective stimulator of the stomach glands.