1. How does food change its consistency and form?
- First, the food enters the mouth. There will be a physical breakdown of the food, also referred to as chewing. Food is manipulated by the tongue, ground by the teeth, and mixed with saliva during chewing. There will also be hydrolysis, which is an enzyme-assisted breakdown of food. As a result, a bolus (a soft, flexible sphere of food that can be easily swallowed) will form. The bolus will then proceed to the stomach after passing through the esophagus. There will be churning and hydrolysis in the stomach. The saliva, food, and gastric juice will all be mixed together. The bolus will gradually dissolve into chyme, a more fluid substance. This is then passed on to the intestines. In the small intestines, hydrolysis will occur once again. Additionally, there is nutrient absorption. The small intestine absorbs approximately 90% of the nutrients and water that enter the digestive system. The large intestine, on the other hand, will absorb water, ions, and vitamin K. After 3-10 hours in the large intestine, chyme has solidified or semisolidified due to water absorption and is now known as feces.
2. How does the body absorb nutrients from the foods we eat?
- Absorption refers to the movement of digested nutrients from the gastrointestinal tract into the blood or lymph. Nutrient absorption occurs primarily in the small intestine. Approximately 90% of all nutrient absorption occurs in the small intestine, with the remaining 10% occurring in the stomach and large intestine. Any undigested or unabsorbed material that remains in the small intestine is transported to the large intestine. All of the chemical and mechanical phases of digestion intend to convert food into forms such as monosaccharides (glucose, fructose, and galactose) from carbohydrates; single amino acids, dipeptides, and tripeptides from proteins; and fatty acids, glycerol, and monoglycerides from triglycerides, all of which can pass through the absorptive epithelial cells lining the mucosa and into the underlying blood and lymphatic vessels. Diffusion, facilitated diffusion, osmosis, and active transport are all methods of absorption.