2 Objectives Label the major organs on a diagram of the digestive system Identify at least three organs that are located in the mouth and aid in the initial breakdown of foodCite two functions of the salivary glandsDescribe how the gastric juices act on food in the stomachExplain how food is absorbed into the body by the villi in the small intestineList at least three functions of the large intestineList a t least four functions of the liverExplain how the pancreas helps digest foodsDescribe at least five diseases of the digestive system
3 Digestive or GI systemPhysical and chemical breakdown of food so that it can be taken into the bloodstream and used by body cells and tissues.Alimentary canal plus accessory organs
4 Alimentary canalLong, muscular tube that begins at the mouth and includes the mouth (oral cavity), pharynx, esophagus, stomach, small intestine, large intestine, and anus.
6 MouthBuccal cavityReceives food- then food is tasted, broken down physically by the teeth, lubricated and partially digested by saliva, and swallowed
7 TeethSpecial structures in the mouth that physically break down food by chewing and grinding.mastication
8 TongueMuscular organ that contains special receptors called taste budsSweet, salty, sour, and bitter sensationsAids in chewing and swallowing
9 Hard palateBony structure that forms the roof of the mouth and separates the mouth from the nasal cavity
10 Soft palateBehind the hard palate, separates the mouth from the nasopharynxUvula- cone-shaped muscular structure, hangs from the middle of the soft palatePrevents food from entering the nasopharynx during swallowing
11 Salivary glandsThree pairs- parotid, sublingual, and submandibular, produce saliva which lubricates the mouth during speech and chewing and moistens food so it can be swallowed easily. Contains an enzyme called salivary amylase which begins the chemical breakdown of carbohydrates or starches into sugars.
12 Pharynx Food chewed and mixed with saliva is called a bolus. When swallowed the bolus enters the pharynx (throat). Carries both food and air.Food-esophagusAir-tracheaDuring swallowing epiglottis closes over larynx to prevent bolus from entering respiratory tract.
13 Esophagus Muscular tube dorsal to trachea. Carries bolus to stomach. Peristalsis- rhythmic , wavelike, involuntary movement of muscles
14 Stomach Enlarged part of alimentary canal. Receives food Mucous membrane lining contains folds called rugaeRugae disappear as stomach fills and expandsCardiac sphincter- circular muscle between esophagus and stomach, closes after food enters to prevent food from going back up.
15 Stomach cont.Pyloric sphincter- circular muscle between stomach and small intestine, keeps food in stomach until food ready to enter small intestine.2-4 hoursFood converted into a semi fluid material , called chyme, by gastric juices produced by glands in stomach
16 Stomach cont. Gastric juices- HCL and enzymes HCL kills bacteria, facilitates iron absorption, and activates the enzyme pepsin.Enzymes- lipases- starts the chemical breakdown of fats, and pepsin- starts protein digestionInfants- enzyme rennin aids in digestion of milk
17 Small Intestine Chyme enters from stomach Coiled section of alimentary canal20 ft length and 1 inch diameterDuodenum (first 9-10 inches)- bile from the gallbladder and liver and pancreatic juice from the pancreas enter this section through ducts or tubes.
18 Small Intestine Jejunum- 8 ft length- middle section Ileum-final 12 ft connects with large intestine at the cecum.Circular muscle called ileocecal valve separates the ileum and cecum- prevents food from returning to ileum.Process of digestion completed in small intestineProducts of digestion absorbed into bloodstream for use by cells
19 Small intestine- intestinal juices Enzymes maltase, sucrase and lactase- breakdown sugarsEnzymes- peptidases- complete digestion of proteinsEnzyme Steapsin (lipase) aids in digestion of fatBile from liver and gall bladder emulsifies (physically breaks down) fats.
20 Small intestine- intestinal juices Pancreatic enzymes- amylase (acts on sugars), trypsin and cymotrypsin (acts on proteins), lipase or steapsin (acts on fats).
21 Small intestine After food digested, absorbed into bloodstream Walls of intestine lined with fingerlike projections called villi.Villi contain blood capillaries and lacteals.Blood capillaries absorb digested nutrients and carry them to liver where they are stored or released into general circulation for use by body cells.
22 Small intestineLacteals absorb most of digested fats and carry them to the thoracic duct in lymphatic system which releases them into circulatory system.When food completed passage through SI, only wastes, indigestible materials, and excess water remain
23 Large Intestine Final section of alimentary canal 5 ft long and 2 inch diameter
24 Functions Absorption of water and remaining nutrients Storage of indigestible materials until eliminatedSynthesis and absorption of some b-complex vitamins and vitamin K by bacteria present in intestineTransportation of the waste products out of the alimentary canal
25 Sections Cecum 1st Connects with ileum of small intestine Contains a small projection called the vermiform appendix
26 ColonAscending colon continues up on right side of body from cecum to lower part of liverTransverse colon extends across the abdomen, below liver and stomach but above small intestineDescending colon extends down the left side of the bodySigmoid colonConnects with descending colonS-shaped section that joins with the rectum
27 Rectum Final 6-8 inches Storage area for indigestibles or wastes Narrow canal called the anal canal which opens at a hole called anusFecal material or stool, the final waste product of digestive process, expelled through this opening
28 liver Largest gland in the body Accessory organ Under diaphragm in upper right quadrant of abdomen
29 Functions Secretes bile Used to emulsify or physically break up fats Makes fats water soluble, which is necessary for absorptionStores sugar in the form of glycogenglycogen is converted to glucoseReleased into the bloodstream when additional blood sugar is needed
30 Functions cont. Stores iron and certain vitamins Produces heparin (prevents blood clotting)Produces blood proteins such as fibrinogen and prothrombin, which aid in clotting of the bloodProduces cholesterolDetoxifies substances such as alcohol and pesticides, destroys bacteria that have been taken into the blood from the intestine
31 Gallbaldder Small muscular sac Under liver attached to it by connective tissueStores and concentrates bile (which it receives from liver)When bile needed in digestive tract to emulsify fats, it contracts and pushes the bile through the common bile duct into duodenum
32 Pancreas Fish-shaped organ located behind stomach Produces pancreatic juicesJuices enter duodenum through pancreatic ductContain enzymes to digest foodPancreatic amylase to break down sugarsTrypsin and chymotrypsin to break down prteinsLipase to act on fats
33 Pancreas cont. Produces insulin Secreted into the bloodstream Regulates the metabolism or burning of carbohydrates to convert glucose to energy