Where does digestion begin in the digestive system?
A.
Stomach
B.
Esophagus
C.
Small intestine
D.
Oral cavity
The correct answer and Explanation is :
The correct answer is D. Oral cavity.
Digestion begins in the oral cavity, where both mechanical and chemical processes initiate the breakdown of food. When food enters the mouth, it is physically broken down by the action of chewing, which is carried out by the teeth. This mechanical process increases the surface area of the food, making it more accessible to enzymatic action.
Simultaneously, the salivary glands, located in and around the oral cavity, secrete saliva. Saliva contains the enzyme amylase, which begins the chemical digestion of carbohydrates. Amylase breaks down complex carbohydrates, like starches, into simpler sugars such as maltose. This enzymatic process is crucial as it starts the digestion of carbohydrates before the food even reaches the stomach.
The process of digestion in the oral cavity is not just about breaking down food; it also involves the formation of a bolus, which is a moist, chewable mass of food. The bolus is formed by the mixing of food with saliva, which makes it easier to swallow. The act of swallowing then propels the bolus into the esophagus, where it continues its journey through the digestive tract.
In summary, the oral cavity is essential for initiating both mechanical and chemical digestion. The mechanical breakdown by chewing and the chemical breakdown by saliva’s enzymatic action set the stage for further digestion and absorption in subsequent parts of the digestive system, including the esophagus, stomach, and small intestine.