Digestive System Physiology
|salivary amylase||enzyme produced by salivary glands and secreted into the mouth. Used in carbohydrate digestion. Breaks down starch into dissacharides.|
|pancreatic amylase||works in the small intestine and used in carbohydrate digestion. Breaks down starch into dissacharides.|
|hydrolysis||chemical reaction in which water reacts with a compound to produce other compounds; involves the splitting of a bond to break down into monomers.|
|pepsin||works in the stomach in the presence of HCl. Used in protein digestion. Breaks down protein into large polypeptides.|
|hydrochloric acid||(HCl) works in the stomach in the presence of pepsinogen . Used in protein digestion. Breaks down protein into large polypeptides.|
|chyme||semi-solid acidic food mass that enters the duodenum from the stomach.|
|deglutition||aka swallowing. Is the result of skeletal muscle activity and occurs in two phases: buccal (mouth) and pharyngeal-esophageal.|
|peristaltic movement||the major means of propelling food through most of the digestive viscera. Waves of contraction followed by waves of relaxation that squeeze foodstuffs through alimentary canal.|
|segmental movements||local constrictions of the organ wall that occur rhythmically. Mixes foodstuffs with digestive juices and increase the rate of absorption.|
|chymotrypsin||pancreatic enzyme that works in the small intestine. Works in protein digestion. Breaks down large polypeptides into small polypeptides.|
|trypsin||pancreatic enzyne that works in the small intestine. Works in protein digestion. Breaks down large polypeptides into small polypeptides.|
|bile||a digestive juice secreted by the liver and stored in the gallbladder; aids in the digestion of fats.|
|lipase||an enzyme secreted in the small intestine that catalyzes the breakdown of fats into individual fatty acids that can be absorbed into the bloodstream.|
|brush border enzymes: carbohydrate digestion||lactase, maltase. Works in the small intestine.|
|brush border enzymes: protein digestion||aminopeptidase, dipeptidase. Works in the small intestine.|
|temperature in enzyme activity||enzymes work best at 37-40* C. Any higher temperature would denature them and they would not function properly.|
|pH in enzyme activity||pepsinogen and HCl (combine to make pepsin), work best at pH of 2, an acidic environment to enable gastric digestion and the breakdown of food to occur. Intestinal digestion occurs at pH 6, and enables the further breakdown so that absorption can take place.|
|gastric digestion lab|| starting material: powdered albumin|
enzymes: pepsin, hydrochloric acid, gastric juice (pepsinogen and HCl combined)
results: gastric digestion occurs only with gastric juice and proper temperature of 37* (test tube turned pink-purple). Acidic environment is necessary.
|digestion of starch lab|| starting material: starch solution|
enzymes: pancreatic juice
reagent: iodine-potassium iodide solution
results: digestion occurs only with proper temperature (body temp of 37*) (test tube turned light brown). Too hot denatures the enzyme. The product of starch digestion is glucose.
|digestion of protein and lipids lab||starting material: litmus milk|
enzymes: pancreatin powder
reagent: litmus in the milk
results: digestion occurs in the presence of an acidic environment (test tube turned purple-red). The product of protein digestion is amino acids, and the product of lipids are fatty acids. Because these products are acids, they increase acidity overall.
|small intestine absorption lab|| starting material: starch, glucose|
reagent: Benedict's solution, iodine-potassim iodide
results: glucose has small molecules that can be absorbed by the small intestine. starch molecules are too large (macromolecules) and can't fit through the pores of the small intestine.
|swallowing processes||buccal: tongue pushes food against soft palate, soft palate pushes up to close off nasal passages; involuntary phase begins|
esophageal: epiglottis covers lower respiratory passages, esophageal sphincter relaxes and food enters esophagus.
pharynx: peristalsis of pharyngeal constrictor muscles forces food down to stomach.