How the food changes consistency and form.
- When the food goes into the mouth, it undergoes mechanical digestion through chewing or mastication. The food is controlled bu the tongue, ground by the teeth, and mixed with saliva, which results into a bolus— a soft, flexible, and easily swallowed mass. Bolus is pushed down into the oropharynx and eventually swallowed into the esophagus. The esophageal glands secrete mucus which reduces the friction and lubricates the bolus. As the bolus reaches the end of the esophagus, the esophageal sphincter relaxes and propels bolus into the stomach. When the bolus has reached the stomach, mixing waves start where in the bolus mixes with the gastric juices, resulting in the soupy liquid called “chime”. From the stomach, the chyme moves into the small intestine where in chemical digestion happens as it depends on the pancreas, liver, and gallbladder. Pancreatic juice contains enzymes which digests starches, proteins, triglycerides, and nucleic acids. Liver secretes bile and is mixed with chyme. Bilirubin in the bile is broken down and one of its product is the stercobilin which gives feces its normal brown color.
How the body was able to absorb the nutrients from the food we eat.
- Most nutrients from the food that we eat are absorbed in the small intestine. About 90% of the absorption of nutrients pccurs in the small intestine and 10% of it occurs in the stomach and large intestines. In the small intestine, chyme mixes with bile, pancreatic juice, and othe digestive juices which participates in the absorption of nutrients. Monosaccharides, single amino acids, dipeptides, fatty acids, glycerol, and monoglycerides are the nutrients being digested and are passed from the gastrointestinal tract into the bloodstream.