Proteins are digested in the stomach and small intestine. Protease enzymes break down proteins into amino acids. Digestion of proteins in the stomach is helped by stomach acid , which is strong hydrochloric acid. This also kills harmful microorganisms that may be in the food. Lipase enzymes break down fat into fatty acids and glycerol. Digestion of fat in the small intestine is helped by bile , made in the liver. Chemical digestion is the enzyme-mediated, hydrolysis process that breaks down large macronutrients into smaller molecules.
Digestion is a form of catabolism: a breakdown of large food molecules i. Catabolism : A simplified outline of the catabolism of proteins, carbohydrates, and fats. Carbohydrates are taken in mainly in the form of plant carbohydrate amylose and animal carbohydrate glycogen together with some sugars, mainly disaccharides.
Glycogen is a multi-branched starch with linkages at the and position. This creates very large granules of multi-branched starch.
Both the parotid and pancreatic amylases hydrolyse the link, but not the terminal links or the links. This breaks amylose down into mainly disaccharides, and glycogen with its linkages into polysaccharides. The net result of these actions are numerous disaccharides and polysaccharides. Enzymes attached to the enterocycytes of the small intestine break these down to monosaccharides.
Hydrolysis by amylase : Both the parotid and pancreatic amylases hydrolyse the link, but not the terminal links or the links. Proteins and polypeptides are digested by hydrolysis of the carbon—nitrogen C—N bond. The proteolytic enzymes are all secreted in an inactive form, to prevent auto-digestion, and are activated in the lumen of the gut. Activation is caused by HCl in the case of the stomach enzyme pepsinogen, and by enteropeptidase and trypsin in the case of the pancreatic enzymes.
Final digestion takes place by small intestine enzymes that are embedded in the brush border of the small intestine. The enzymes are divided into endo- and exo-peptidases. Stomach pepsin cleaves the interior bonds of the amino acids, and is particularly important for its ability to digest collagen. This is a major constituent of the connective tissue of meat. Pancreatitis affects digestion because enzymes are not available. This leads to diarrhea, weight loss, and malnutrition. Pancreatic cancer.
Not having enough pancreatic enzymes for normal digestion is very common in pancreatic cancer. Symptoms can include weight loss, loss of appetite, indigestion, and fatty stools.
Your pancreas is important for digesting food and managing your use of sugar for energy after digestion. If you have any symptoms of pancreatic digestion problems, like loss of appetite, abdominal pain, fatty stools, or weight loss, call your healthcare provider. Health Home Conditions and Diseases. Pancreatic enzymes Your pancreas creates natural juices called pancreatic enzymes to break down foods. These are the different enzymes: Lipase.
Pancreatic hormones Many groups of cells produce hormones inside your pancreas. Pancreatic hormones include: Insulin. Common pancreatic problems and digestion Diabetes, pancreatitis, and pancreatic cancer are three common problems that affect the pancreas.
Here is how they can affect digestion: Diabetes. Typically, bile is concentrated five-fold in the gall bladder by absorption of water and small electrolytes - virtually all of the organic molecules are retained. Secretion into bile is a major route for eliminating cholesterol. Free cholesterol is virtually insoluble in aqueous solutions, but in bile, it is made soluble by bile acids and lipids like lecithin. Gallstones , most of which are composed predominantly of cholesterol, result from processes that allow cholesterol to precipitate from solution in bile.
Bile acids are derivatives of cholesterol synthesized in the hepatocyte. Cholesterol, ingested as part of the diet or derived from hepatic synthesis is converted into the bile acids cholic and chenodeoxycholic acids, which are then conjugated to an amino acid glycine or taurine to yield the conjugated form that is actively secreted into cannaliculi.
Bile acids are facial amphipathic, that is, they contain both hydrophobic lipid soluble and polar hydrophilic faces.
The cholesterol-derived portion of a bile acid has one face that is hydrophobic that with methyl groups and one that is hydrophilic that with the hydroxyl groups ; the amino acid conjugate is polar and hydrophilic.
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