Is all the food you eat used in the body during digestion?

Answer 1

Before answering this question you should be aware of the meaning of food and different types of food.

The body needs Proteins, Carbohydrates and fat in order to grow. But this can not function without the breaking of food i.e Digestion. Digestion helps the food to be broken down into simple particles so that can enter the body through the flow of blood.

In mammals, food enters the mouth, being chewed by teeth, with chemical processing beginning with chemicals in the saliva from the salivary glands. Then it travels down the esophagus into the stomach, where acid both kills most contaminating microorganisms and begins mechanical break down of some food (e.g., denaturation of protein), and chemical alteration of some. After some time (typically an hour or two in humans, 4-6 hours in dogs, somewhat shorter duration in house cats, ...), the results go through the small intestine, through the large intestine, and are excreted during defecation.

Human digestion process

Upper and Lower human gastrointestinal tract

The whole digestive system is around 9 meters long. In a healthy human adult this process can take between 24 and 72 hours.

Phases of gastric secretion

• Cephalic phase - This phase occurs before food enters the stomach and involves preparation of the body for eating and digestion. Sight and thought stimulate the cerebral cortex. Taste and smell stimulus is sent to the hypothalamus and medulla oblongata. After this it is routed through the vagus nerve and release of acetylcholine. Gastric secretion at this phase rises to 40% of maximum rate. Acidity in the stomach is not buffered by food at this point and thus acts to inhibit parietal (secretes acid) and G cell (secretes gastrin) activity via D cell secretion of somatostatin.
• Gastric phase - This phase takes 3 to 4 hours. It is stimulated by distention of the stomach, presence of food in stomach and decrease in pH. Distention activates long and myentric reflexes. This activates the release of acetylcholine which stimulates the release of more gastric juices. As protein enters the stomach, it binds to hydrogen ions, which lowers the pH of the stomach to around pH 1-3. Inhibition of gastrin and HCl secretion is lifted. This triggers G cells to release gastrin, which in turn stimulates parietal cells to secrete HCl. HCl release is also triggered by acetylcholine and histamine.
• Intestinal phase - This phase has 2 parts, the excitatory and the inhibitory. Partially-digested food fills the duodenum. This triggers intestinal gastrin to be released. Enterogastric reflex inhibits vagal nuclei, activating sympathetic fibers causing the pyloric sphincter to tighten to prevent more food from entering, and inhibits local reflexes.

There fore; All kinds of food must be digested.

Answer 2

no