What is the correct sequence for the passage of food through the human digestive tract?

Answer 1

First, the food enters through the mouth and food is masticated and chewed, while oral juices secreted by oral glands are mixed by the tongue. This juice contains salivary amylase, which primarily breaks down carbohydrates, in forms of sugar and starch, and mucin, which lubricates the food in order for it to go smoothly down the esophagus. After being swallowed, it will roll down to the pharynx, which separates the passageway for food and air. We sometimes choke when food enters the wrong passageway, that is, in the event that food goes down the trachea, or the windpipe. The initial reaction to this is to choke. When food goes into the right path, we go to the esophagus, which us a muscular tube that leads to the stomach. The lubrication of the food by the mucin of the saliva and the peristalsis (wave-like motion of the esophagus to assist the food on going to the stomach smoothly) helps for it to reach the stomach quickly. The stomach is the first chamber of chemical and physical digestion for the food. Internal folds inside the stomach called rugae help in grinding and breaking down the food while the stomach churns. That is the physical digestion part. The chemical digestion kicks in when the gastric juices, secreted by gastric glands found inside the stomach, break down the food. Some of these gastric juices are gastric amylase, which break down carbohydrates, trypsin which breaks down proteins, and lipase which breaks down fat. The technical term used to refer to the food broken down in the stomach is chyme. The chyme, then, is regulated by the phyloric sphincter, a valve which regulates the amount of chyme entering the small intestine. The small intestine is where most of the chemical digestion and absorption occurs. The accessory digestive glands help by secreting juices, such as bile, some hydrochloric acid (HCl) and other enzymes. The nutrients are "absorbed" by finger-like projections called villi. What actually happens, is that the villi contain capillaries, very thin blood vessels, so thin, that red blood cells need to pass through a single file to fit; these capillaries are where the nutrients from the food digested diffuse into. These capillaries then lead to larger blood vessels, and the nutrients are sent to cells via the blood. Now that the essential materials are distributed, the "leftovers" are sent to the large intestine, where water diffuses into capillaries, and some essential materials not absorbed in the small intestine. What is left is waste, then sent to the rectum, which is a temporary storage of feces. When the rectum is a bit full, the waste will exit the body through the anus, and that is feces.

That is what I know of the digestive system. Hope it helped!

Good luck! ;]