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Chapter 14 Digestive System Organs divided into 2 groups: Alimentary Canal or Gastrointestinal (GI) Tract: Functions are ingest, digest, absorb, & defecate Ex. Mouth, Esophagus, Stomach, Liver, Gall Bladder, Pancreas, Small Intestine, Large Intestine, Anus Accessory Digestive Organs: Assist in process of digestive breakdown Ex. Teeth, Tongue, and Digestive glands How long is your GI tract?? About 30 feet long = 10 yards (FIRST DOWN!) Mouth Mastication – the act of chewing food Digestion starts before you even take your first bite. Smell of food makes salivary glands secrete saliva. Mechanical and chemical digestion occurs 3 salivary glands involved: Parotid, Sublingual, Submandibular Saliva contains enzyme, Amylase, which breaks down polysaccharides (starch) to disaccharides (maltose) Pharynx Tube that connects mouth to esophagus Epiglottis covers the opening to the trachea (windpipe) so food does not get there Walls of pharynx have two skeletal muscle layers: Inner layer runs longitudinally Outer layer (constrictor muscles) run around the wall in a circular fashion Peristalsis – alternating contractions of muscles propels food along GI tract Esophagus Tube that connects pharynx to stomach About 25 cm long Stomach C-shaped organ located inferiorly to diaphragm and liver Cardioesophageal sphincter is located between esophagus and stomach Chemical and mechanical digestion occurs Breakdown of proteins starts here Pyloric sphincter is located between stomach and small intestine Contains gastric juice that is made of pepsinogens (protein-digesting enzymes) and hydrochloric acid After food is processed, the food is called chyme which resembles a heavy cream. Pancreas Soft, pink, triangular gland extends from spleen to duodenum (start of small intestine) Produces enzymes in duodenum as an alkaline fluid to neutralize acidic chyme from stomach and enzymes break down digestible foods Liver Largest gland in the body; located inferior to diaphragm Has 4 lobes Has many metabolic and regulatory functions including producing bile and releasing it into duodenum Bile is yellow-to-green that contains bile salts that emsulify (break down) fats Gallbladder Small, green sac found inferior to liver Stores the bile made by liver Small Intestine Tube connects stomach and large intestine Digestion of proteins, lipids (fats), & carbohydrates Primary function is absorption of food and nutrients found in food Diffusion of nutrients from food into bloodstream 3 parts: Duodenum, Jejunum, Ileum Mesentery – membrane that contains blood vessels, lymph vessels, & nerve that allows small intestine to coil Large Intestine Tube that connects small intestine to anus Primary function is to absorb water from remaining food matter and pass indigestible waste out body Appendix – first part of large intestine that serves on function 4 parts: Ascending colon, Transverse colon, Descending colon, Sigmoid colon, Rectum