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mechanical digestion physical breakdown of food into smaller particles by chewing of the teeth and churning contractions of the stomach chemical digestion series of hydrolysis reactions that break dietat macromolecules into their monomers...polysac into monosac prot into amino acids fats into monoglycerides and fatty acids and nucleic acids into nucleotides carried out by digestive enzymes produced by salv glands stomach pancreas and sm intestines digestive tract muscular tube includes mouth pharynx espohagus stomach sm and lg intestines mastication chewing breaks down food into pieces small enought ot be swallowed salivary amylase an enzyme that begins starch digestion in mouth lingual lipase an enzyme that is activated by the stomach acid and digests fat after the food is swallowed mucus binds and lubricates the food mass and aids in swallowing lysozyme an enzyme that kills bacteria immunoglobulin A IgA an antibody that inhibits bacterial growth electrolytes including sodium potassium chloride phosphate and bicarbonate salts intrinsic salivary glands small glands dispersed amid other oral tissues include lingual glands in tongue labial glands on inside of lips and buccal glands on inside of cheeks extrinsic salivary glands three pairs of longer more discrete organs located outiside oral mucosa parotid submandibular and sublingual parotid gland gland located beneath skin anterior to earlobe submandibular gland gland located halfway along the body of the mandible medial to its margin sublingual gland gland located in the floor of mouth bolus salivary amylase begins to digest startch as the food is chewed which the musus in the saliva binds food to particles into a soft slippery easily swallowed mass called ____ pharyngeal constrictors force food downward during swallowing lower esophageal sphinceter LES prevents stomach contents from regurgitating into the esophogus thus protecting the esophogeal mucosa from the erosive effect of stomach acid esophageal glands glands in the esophogus that secrete lubricating mucus into lumen deglutition swallowing buccal phase first phase of swallowing which is under voluntary control. pharyngoesophageal phase second phase of swallowing is involuntary. three actions block food and drink from reentering the mouth or nasal cav. or larynx...root of tongue blocks oral cavtiy, soft palate rises and blocks nasopharynx, infrahyoid muscles pull the larynx up to meet the epiglottis while vestibular folds adduct to close airway peristalsis as the bolus eneters the esophogus it stretches and triggers ______ a wave of muscular contraction that pushes the bolus ahead of it chyme stomach mechanically breaks up food particals liquifies the food and behins the chemical digestion of protein and fat this produces a soupy or pasty mixture of semi digested food called ____ cardiac, fundic, body, and pyloric region regions of stomach are? gastric rugae wrinkles in the stomach mucous cells stomach cells that sevrete mucus prodominent in the cardiac and pyloric glands Accessory Organs Salivary glands, Liver, Gallbladder, & Pancreas; These organs NEVER touch food directly, but they release various enzymes & fluids to help the digestion process Ingestion Process by which food/fluid enters the mouth Absorption Process by which nutrients are taken into the small intestine Defacation Process by which indigestible material is removed from the digestive tract Incisors Front teeth of the mouth; they are responsible for biting Canines Also known as Bicuspids, these teeth have sharp, pointy edges that tear food Premolars (Cuspids) & Molars Teeth found near the back of the mouth that help to grind food Enamel The protective white covering on the crown of the tooth Pharynx The throat Esophagus The food tube that connects the mouth to the stomach Epiglottis The piece of cartilage that closes over the trachea when swallowing to prevent food from "going down the wrong pipe" Gastroesophageal Sphincter Muscle that connects the esophagus and stomach, and helps keep the stomach contents in the stomach Cardia Portion of the stomach that surrounds the opening Fundus Portion of the stomach that is found to the left of the cardia Body of the Stomach Portion of the stomach that is found in the center of the stomach, below the Fundus Pylorus Narrow, inferior region of the stomach Chyme Pasty fluid that is a combination of partially digested food and gastric juice Pyloric Sphinchter The muscle that slowly releases chyme from the stomach into the small intestine Duodenum 1st part of the small intestines that attach to the stomach Jejunum Midsection of the small intestine Ileum Last part of the small intestine that attaches to the large intestines Villi Fingerlike projectsion inside the tube of the small intestine that further increase surface area Mesentery The thin tissue on the outside of the small intestine that connects the digestive system with the cardiovascular system; it is filled with blood vessels to carry the absorbed nutrients into the bloodstream Small Intestine Part of the digestive system responsible for absorbing the nutrients that are in food Stomach Digestive organ that is responsible for temporarily storing food and mixing it with gastric juices to break it down Large Intestine Digestive organ that is responsible for removing all of the indigestible material from the digestive system, as well as re-absorbing water and making Vitamin K Liver Digestive organ that MAKES bile, in addition to filtering the blood, storing various Vitamins & Minerals, and regulating blood components Pancreas Digestive organ that regulates the hormones Insulin and Glucagon secretes pancreatic juice Gallbladder pear shaped sac on the underside of the liver that serves to store and concentrate bile Hepatocytes Specialized cells in the liver that make bile Glycogen Storage form of glucose Acini Specialized cells in the pancreas that secrete pancreatic juice Pancreatic Islets (Islets of Langerhans) Specialized cells in the pancreas that secrete Insulin & Glucagon regenerative cells cells of the stomach glands that divide rapidly and produce continuous supply of new cells parietal cells cells of the stomach glands that secret hydrochloric acid, intrinsic factor, and ghrelin mainly in gastric glands few in pyloric chief cells cells of stomach glands; most numerous secrete enzymes gastric lipase and pepsingen, mainly in gastric glands enterodocrine cells cells of stomach glands; secrete hormones and paracrince messangers that reg digestion; located in all regions of stomach but abundant in gastric/pyloric glands 8 diff kinds each produce diff chemical messangers mucus cardiac and pyloric glands secrete mainly _____ acid and enzymes gastric glands secrete mainly ___ and ___ gastric juice gastric glands produce 2 to 3 l of this per day mainly composed of water hydrohloric acid and pepsin hydrochloric acid secreted by parietal cells in stomach; known as stomach acid; it activates the enzymes pepsin and lingual lipase, it breaks up connective tissues and plant cell walls helping to liquefy food to form chyme, it converts ingested ferric ions to ferrous inons a form of iron that can be absorbed and used for hemoglobhin synth, it contributes to nonspecific disease resistance by destroying most ingested pathogens pepsin a form of zymogen that is converted to active enzyme by removal of its amino acids. chief cells secrete pepsinogen then hydrocholoric acid removes some of its amino acids and converts it to _____ digests protein and since it itself is a protein it is known as AUTOCATALYTIC effect DIGEST DIETARY PROT TO SHORTER PEPTIDE CHAINS which then pass to the sm intestine where their digestion is complete gastric lipase secreted by chief cells; digests 10 to 15% of the dietary fat in stomach the remainder is digested by sm intestine intrinsic factor secreted by parietal cells of stomach glands; essential for absorption of vitamin b12 by sm intestine. binds vitamin b12 and the intestinal cells then absorb this complex by receptor mediaded endocytosis. with out vitamin b12 hemoglobin cannot be synth. and pernicious anemia develps chemical messangers gastric and pyloric glands have various kinds of enteroendocrine cells that collectively produce many ________ most of these are hormones they travel in the bld strm and stimulate distant target cells gut brain peptides chemical messanger that is produced in both the digestive tract and the central nervous system they include subs P vasoactive intestinal peptide (VIP) ....etc receptive relaxation response the arriving food stretches the stomach and activates the ________ of the sm muscle the stomach briefly resists stretching but then relaxes and is able to accommodate more food vomiting the forceful ejection of stomach and intestinal contents (chyme) from the mouth it invloves mult. muscular contractions integrated by the emetic center of the medulla retching thoracic expansion and abdominal contraction create a pressure difference that dilates the esophogus (during vomitting) projectile vomiting sudden vomiting with no prior nausea or retching mucous coat protection of stomach; thick highly alkaline musus resists the action of acid and enzymes tight junctions protection of stomach; epithelial cells are joined by these and prevent gastric juice from seeping between them epithelial cell replacement protection of stomach; only live 3 to 6 days and are then sloughed off into the chyme and digested with the food, they are replaced just as rapidly by cell div in the gastric pits cephalic phase stage in which the stomach responds to the mere sight smell taste or thought of food, vagus nerve fibers from the medulla stimulate the enteric nervous sys of the stomach which in turn stim gastric secretion gastric phase phase in which swallowed food and semidigested prot (pep. and amino acids) activate gastric activity. 2/3 of gastric secretion occurs during this phase. ingested food stimulates gastric sec in two ways: stretching stomach and raising the pH of its contents stretch activates short reflex and long reflex histamine and gastrin also stim. acid and enxyme sec. intestinal phase phase in which the duodenum responds to arriving chyme and moderates gastric act. through hormones and nervous reflexes. the duodenum initially enhances gas. sec. but then inhibits it. stretching of duodenum stim stomach and peptides/amino acids in chyme to stim g cells of duodeunum to secrete more gastrin. secretin cck and enterogastric reflex inhibit gastric sec and motitlity while duodenum processes the chyme already in it enterogastric reflex triggered bu the acid and semidigested food in the intestinal phase of the gastric secretion that lead the duodenum to send inhibitory signals to stomach by way of enteric nervous sys and sends signals to medulla bile yellowish green fluid containing minerals cholesterol nuetral fats phospholipids bile pigments and bile acids urobilinogen recponsible for the brown color of feces acholic feces in absense of bile secretion the feces are grayish white and marked with streaks of undigested fat...this is called ____ bile acids steriods synth from cholesterol ...this and lecithin a phospholipid aid in fat digestion and absorption cholecystokinin cck; regulation of pancreatic secretion; secreted primarily in response to fats in sm intestine stim pancreatic acini to secrete enzymes. it induces contractions of the gallbladder and relaxation of the hepatopancreatic schincter thus causing discharge of bile into the duodenum secretin regulation of pancreatic secretion; secreted mainly in response to the acidity of chyme arriving from the stomach. stim. ducts of both the liver and pancreas to secrete an abundant sodium bicarbonate solution. this flushed the enzymes into the duodenum intestinal juice secreted by intestinal crypts especially in response to acid hypertonic chyme and distension of the intestins. segmentation movement in which stationary ringlike contrictions appear at sev places along the intestine and then relax as new contrictins form elsewhere most common type of intestinal contraction migrating motor complex the successive overlapping waves of contraction in the intestine are called ____ they milk the chyme toward the colon over a prd of 2 hrs starch the most digestible dietary carbohydrate amino acids these are absorbed by the sm intest from three sources dietary prot digestive enzymes and sloughed epithilal cells by these enzymes proteases enzymes that digest proteins lipases fats are digested by enzymes called bacterial flora bacteria that resides in the lrg intestine helps us get more nutrution from our food then we would without them causes intestinal gas flatus fart; most of it is swallowed air that has worked its way through the digestive tract but bacterial flora add to it haustral contractions most common type of colonic motility is a type of segmentation called _____ mass movements cause larger contractions of the colon and occur 3 times a day last about 15 min and move residue sev cm at a time intrinsic defecation reflex this reflex operates entirely within the myeneteric nerve plexus. stretch signals travel throught the plexus to descending and sigmoid colon and rectum. this drives feces downward and it relaxes the internal anal sphincter parasympathetic defecation reflex this is a spinal reflex. stretch sig are transmitted to spinal cord and motor sign turn back by pelvic nerves relaxes internal anal spchicter