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Digestive System
Biology 12
| Term | Definition |
|---|---|
| absorption | food nutrients enter the villi of the ileum. requires transport proteins. in the ileum the transport mechanism is ATP requiring |
| anaerobic bacteria | bacteria that survive in the absence of oxygen |
| anus | posterior opening of the digestive tract, protected by the anal sphincter |
| appendix | vestigial projection from the caecum (first part of the large intestine) no functions are attributed to it |
| bile | liver secretion that passes through the bile duct into the duodenum. it is stored in the gall bladder until its entry into the duodenum is stimulated. it's an emulsifier of lipids |
| capillary | smallest type of blood vessel. facilitate capillary-tissue fluid exchange. collection of capillaries between an arteriole and a venule is a capillary bed. sphincter muscles in the arterioles regulate the amount of blood flowing through a capillary bed |
| cardiac sphincter | muscular constriction along the gastro-inestinal tract, found where the esophagus meets the stomach. |
| chemical digestion | hydrolytic reactions that reduce food molecules to monomers by enzymatic activity. occurs in the mouth(salivary amylase), stomach(pepsin), duodenum(different enzymes) |
| digestive enzyme | hydrolytic enzyme that chemically breaks food molecules into monomers. found in saliva, gastric juice, pancreatic juice and intestinal juice |
| digestive tract | tube that conducts food through the body from the mouth to the anus. specialized into organs and has accessory organs attached that function to digest food and prepare undigested material for defecation |
| duodenum | first part of small intestine. food materials are released from stomach through the pyloric sphincter. majority of digestion activity takes place. bile from gall bladder enters here and pancreatic juice. |
| emulsification | making of an emulsion by physical suspension of immiscible substances in a solute. bile is an emulsifier of fats because it breaks them down into droplets causing them to suspend in the aqueous chyme. |
| epiglottis | ventral flap of tissue on top of the trachea. normally it is opened however it closes during swallowing preventing food from entering the air passages |
| esophagus | found behind the trachea. expands from the pharynx to the cardiac sphincter. walls of esophagus are lined with circular and longitudinal muscles that conduct peristalsis to move food material |
| gall bladder | stores bile and when its release is signaled bile enters the duodenum and emulsifies fats to increase the efficiency of lipase |
| gastric juice | digestive secretion produced by the stomach. released as a result of the action of the hormone gastrin, it contains HCL, pepsinogen and mucus |
| hyrdrochloric acid | acid component of gastric juice |
| insulin | protein hormone in the pancreas. promotes the uptake and utilization of blood sugar by cells. it lowers blood sugar levels. it is a fairly short protein and its effects are counteracted by glucagon |
| intestinal juice | digestive secretion of the small intestine. contains a variety of enzymes that complete the chemical digestion of food. (dissaccharidases,peptides,nucleases and water) |
| lacteals | beginning of the lymphatic system in the villi of the small intestine. transport products of fat digestion away from intestines |
| large intestine (colon) | 4 major sections: ascending, transverse, descending colons and rectum. appendix is a vestigial pouch extending from the caecum. functions to absorb water left over from the digestion process and contains bacteria |
| lipase | produced by the pancreas and enters the duodenum as a component of pancreatic juice. products of its activity are fatty acids and glycerol. efficiency is increased by the activity of bile |
| liver | largest inner organ of the body. located posterior to the diaphragm and has many functions; production of bile, conversion of ammonia into urea, storage of glucose as glycogen, production of globulins etc |
| maltase | disaccharide that is made by combining two glucose molecules together. digestion of starch and glycogen by amylase enzymes produces maltose. further digested into glucose by maltase |
| mircovillus | membrane extension of the cytoplasm of columnar epithelial cells that line villi. increase the contact surface area of the villi against the intestinal lumen, increasing the absorption of products of digestion |
| nuclease | nucleic acid-digesting enzyme. component of both pancreatic and intestinal juice |
| pancreas | endocrine and exocrine functions. as an endocrine gland its islets of langerhans produce hormones insulin and glucagon. as an exocrine gland it produces pancreatic juice |
| pancreatic amylase | component of pancreatic juice that digests starch and glycogen into maltose |
| pancreatic juice | exocrine secretion from the pancreas - contains pancreatic amylase, trypsin, lipase, nucleases, sodium bicarbonate and water |
| pepsin | protease enzyme - pepsin breaks some of the peptide bonds holding amino acids together producing polypeptides which are sections of proteins of various lengths |
| pepsinogen | component of gastric juive - HCL, another component of gastric juice activates it |
| peptidase | breaks peptide bonds (peptides of various sorts are components of intestinal juice) |
| peristalsis | result of coordinated contractions of longitudinal and citcular muslces -provides movement of materials along tubes that would normally be closed. accounts for swallowing and movement of material all along the intestinal tract-moves urine along ureter |
| pH | measure of hydrogen ions in a solution |
| pharynx | back of the mouth where food and air travel. base is specialized by having opening to the esophagus and trachea. |
| physical digestion | mechanical breaking apart of food materials. occurs in the mouth (chewing or mastication) in the stomach(churning) and in the duodenum(emulsification of lipids by bile) |
| protease | protein-digesting enzyme. to avoid their production in a cell protease are produced in an inactive form. pepsinogen and trypsinogen are proteases. |
| pyloric sphincter | valve at the bottom of the stomach-relaxes to permit small amounts of acid chyme into the duodenum at a time so it can be digested further once neutralized |
| rectum | last portion of the large intestine. stores and compacts feeces until defecation |
| salivary amylase | starch digesting enzyme that is a component of saliva. it is neutral to contrast pancreatic amylase. it is denatured in the stomach and digested with any other protein that is swallowed |
| salivary gland | one of the three sets of exocrine glands that deliver mucus and salivary amylase to the mouth |
| salivary juice | combination of salivary amylase and mucus thats produced and delivered to the mouth through ducts from salivary glands |
| small intestine | three parts; duodenum, jejunum and ileum-main role is digestion and reabsorption of nutrients. |
| sodium bicarbonate | buffering component of pancreatic juice. bicarbonate ions maintain pH of chyme at about 8.2 which is optimal for the function of the pancreatic enzymes |
| stomach | lies on the left side of the body and has two main roles; mix and store food and regulate the rate of food movement |
| swallowing | initiates movement of a ball of food down the esophagus. controlled by the medulla oblongata. |
| trypsin | protease enzyme component of pancreatic juice. produced as trypsinogen a precursor. activated by the enzyme enterokinase before it enters the duodenum where it functions to digest protein |
| villus | inner wall of the ileum. contain blood capillaries and lacteal and function for the absorption of products of digestion |
Created by:
alubbe
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