Describe the major events of digestion that occur in the mouth, stomach, and small intestine

Question

What will be an ideal response?

Answer 1

Mouth: The process of digestion begins in the mouth. During chewing, teeth crush large pieces of food into smaller ones, and fluids from foods, beverages, and salivary glands blend with these pieces to ease swallowing. Fluids also help dissolve the food so that the tongue can taste it; only particles in solution can react with taste buds. When stimulated, the taste buds detect one, or a combination, of the five basic taste sensations: sweet, sour, bitter, salty and umami, a savory flavor commonly associated with monosodium glutamate. In addition to these chemical triggers, aroma, appearance, texture, and temperature also affect a food's flavor.

The tongue provides taste sensations and moves food around the mouth, facilitating chewing and swallowing. When a mouthful of food is swallowed, it passes through the pharynx, a short tube that is shared by both the digestive system and the respiratory system. To bypass the entrance to the lungs, the epiglottis closes off the airway so that choking doesn't occur when swallowing. After a mouthful of food has been chewed and swallowed, it is called a bolus.

Esophagus: The esophagus has a sphincter muscle at each end. During a swallow, the upper esophageal sphincter opens. The bolus then slides down the esophagus, which passes through a hole in the diaphragm to the stomach. The lower esophageal sphincter at the entrance to the stomach closes behind the bolus so that it proceeds forward and doesn't slip back into the esophagus.

Stomach: The stomach retains the bolus for a while in its upper portion. Little by little, the stomach transfers the food to its lower portion, adds juices to it, and grinds it to a semiliquid mass called chyme. Then, bit by bit, the stomach releases the chyme through the pyloric sphincter, which opens into the small intestine and then closes behind the chyme.

Small intestine: At the beginning of the small intestine, the chyme bypasses the opening from the common bile duct, which is dripping fluids into the small intestine from two organs outside the GI tract—the gallbladder and the pancreas. The chyme travels on down the small intestine through its three segments—the duodenum, the jejunum, and the ileum—almost 10 feet of tubing coiled within the abdomen.