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Why is the mouth the starting point of digestion? Uncover the secrets hidden in the mouth!
In the huge process of digestion, the mouth undoubtedly plays a vital role. This small opening is not only the first step for food to enter our body, but also starts the engine of the digestive system. The digestive process begins the moment food passes through the mouth and comes into contact with saliva.
After eating food, the teeth in the mouth begin to mechanically digest the food, which is called chewing. Chewing not only cuts food into smaller pieces, it also allows food to mix thoroughly with saliva. Enzymes in saliva, such as salivary amylase, begin the initial chemical breakdown of starch, an example of chemical digestion.
According to research, increasing the number of chews per bite increases related gut hormones and may reduce self-reported hunger and food intake.
At the same time, other components in saliva such as mucus and electrolytes, such as bicarbonate (HCO−3), provide the ideal pH environment for the enzyme to work effectively. About 30% of starch is hydrolyzed into disaccharides in the mouth. In this process, the food is transformed into a smooth spherical mass called a "bolus".
After chewing is complete, the ball passes through the esophagus and into the stomach. In the stomach, gastric juice begins to digest proteins. Gastric juice is mainly composed of hydrochloric acid and pepsin. Although these components can damage the stomach wall, mucus and bicarbonate provide protection and help the stomach resist these strong acids.
The mechanical mixing motion of the stomach stirs the food through peristaltic waves, allowing it to further mix with digestive enzymes.
The human digestive system is a complex process consisting of four basic steps: ingestion, mechanical and chemical digestion, absorption, and excretion. In the mouth, eating of food is accompanied by the secretion of saliva and digestive enzymes for predigestion. During the entire digestion process, food first passes through the mouth, then the stomach, and then enters the small intestine for further digestion and absorption.
The small intestine is the primary site where most nutrients are absorbed, and the digestive process becomes more efficient here. The remaining parts of the food are further fermented in the large intestine, water is absorbed, and eventually waste is excreted from the body.
When food enters the small intestine, it involves the secretion of a large amount of digestive enzymes and bile, where various nutrients are finally absorbed and returned to the blood system.
Different animals also have different evolutions of their digestive systems, with some species relying on external digestion while most animals have more efficient internal digestive systems. This not only improves nutrient absorption, but also allows more effective control of the chemical environment. As evolution progresses, animals have evolved various specialized organs and behaviors to optimize the digestion process of food.
For example, the beaks of birds evolved appropriately for different ecological niches to be able to efficiently open hard seeds. In addition, the function of the tongue is also very important. It helps position and transform food inside the mouth, and kneads it into balls through love, which can be more easily delivered into the esophagus.
Whether it is the diversity of the animal kingdom or the unique chewing and digestion methods of humans, the digestion process of food is an operation full of wisdom. The first reaction in the mouth is not only to meet basic survival needs, but also the result of the cooperation of a complex biological system.
We can’t help but wonder, does your digestive system hold any secrets that deserve further exploration?
