Exam 3 Review:  Chapter 23:  Intestinal Digestion

carbohydrate digestion - The process by which carbohydrates are converted into simple sugars which can be absorbed and assimilated by the body; it is accomplished in the digestive system by the mechanical and enzymatic breakdown. [Note:  There is a limited amount of indiscriminant acid hydrolysis of carbohydrates in the stomach due to the action of gastric HCl; carbohydrates are split into di- and mono-saccharides by salivary amylase in the mouth and pancreatic amylase in the duodenum and disaccharides are split into monosaccharides by disaccharidases (brush border enzymes) in the duodenum.]

protein digestion - The process by which proteins are converted into individual amino acids which can be absorbed and assimilated by the body; it is accomplished in the digestive system by the mechanical and enzymatic breakdown. [Note:  There is a limited amount of indiscriminant acid hydrolysis of proteins in the stomach due to the action of gastric HCl; proteins are split into smaller peptides and ultimately into individual amino acids by pepsin in the stomach and pancreatic proteases (trypsin, chymotrypsin, carboxypeptidase, elastase) in the duodenum.]

lipid digestion - The process by which lipids are converted into small, absorbable lipids, (e.g., glycerol, fatty acids, cholesterol, etc.) which can be absorbed and assimilated by the body; it is accomplished in the digestive system by the mechanical and enzymatic breakdown. [Note:  There is a limited amount of indiscriminant acid hydrolysis of lipids in the stomach due to the action of gastric HCl; bile from the liver and gall bladder assist in chemical digestion by emulsifying the lipids in the chyme; lipids are split into glycerol and fatty acids by lingual lipase in the mouth and pancreatic lipase and phospholipase in the duodenum.]

micelles - The submicroscopic aggregation of molecules held together by noncovalent bonds, forming a suspended droplet in a colloidal system; in the gastrointestinal tract, the form lipids take, when emulsified by an external layer of bile salts and acids in the chyme, which can be absorbed by the intestinal lining epithelial cells.

nucleic acid digestion - The process by which nucleic acids are converted into small, absorbable components, (e.g., pentose sugars, nitrogenous bases, phosphate ions) which can be absorbed and assimilated by the body; it is accomplished in the digestive system by the mechanical and enzymatic breakdown. [Note:  There is a limited amount of indiscriminant acid hydrolysis of nucleic acids in the stomach due to the action of gastric HCl; nucleic acids are split into nucleotides by pancreatic nucleases and nucleotides are split into smaller constituents by nucleotidases (brush border enzymes) in the duodenum.]

electrolytes - Any of various charged ions, such as sodium, potassium, or chloride, etc., required by cells to regulate the electric charge and flow of water molecules across the cell membrane; they play many additional roles in the biochemistry of metabolism.

Describe:

4. the absorption of carbohydrates, amino acids, and lipids.