The Digestive System

1. The Digestive System Eric Soza, Nick Soto, Andres Padilla Period 2 2/10/15

2. Alimentary Canal • Extends from the mouth to the anus, includes accessory organs • Mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anal canal • Accessory organs- salivary glands, liver, gallbladder, and pancreas • About 8 meters long • 4 layers • Mucosa • Submucosa • Muscular layer • Serosa • Segmentation and Peristalsis

3. Mouth • 1st portion of alimentary canal • Receives food, begins digestion • Mastication

4. Cheeks and Lips • Form lateral walls of mouth • Subcutaneous fat • Muscles associated with chewing • Stratified squamous epithelium • Mobile structure • Skeletal muscles and sensory receptors • Red color due to blood vessels

5. Tongue • Oral cavity, thick • Lingual frenulum • Papillae • Lingual tonsils

6. Palate • Roof of oral cavity • Hard and Soft • Uvula • Palatine tonsils • Pharyngeal tonsils

7. Teeth • Hardest structures in the body • Types (primary, etc.) • Crown, enamels, root canals • Help break down food into pieces

8. Salivary Glands • Function: • Overall saliva begins chemical digestion of carbohydrates, cleans teeth and mouth, and binds food • Two types of secretory cells: • Serous Cells- secrete salivary amylase • Mucous Cells- secrete thick liquid

9. Salivary Glands • Three major glands: • Parotid Glands- Largest, secretes salivary amylase rich liquid • Submandibular Glands- Secretes a fluid that is equally serous and mucus • Sublingual Glands- Secretes a thick mucus fluid

11. Salivary Glands • Two types of secretion Stimuli: • Sympathetic- impulses that secrete viscous saliva • Parasympathetic- secrete watery saliva, activated by sight, taste, smell, or thought of pleasant food

12. Swallowing • 3 stages • Voluntary; food chewed and mixed with saliva; bolus. • Swallowing reflex at pharyngeal opening • Peristalsis transports food from esophagus to stomach

13. Pharynx and Esophagus • Pharynx connects nasal and oral cavities with larynx and esophagus • Nasopharynx • Oropharynx • Laryngopharynx • Swallowing stages • Peristalsis

14. Stomach • Has three regions: • Cardiac region: small area near esophageal opening • Funic region: temporary storage area • Pyloric region: narrows and becomes pyloric canal • Pyloric sphincter is the valve that control gastric emptying

15. Stomach • Gastric Glands: • Mucous cell- alkaline secretion that protects stomach wall • Parietal cells- (oxyntic cells) release hydrochloric acid • Also secretes intrinsic factor needed for absorption of vitamin B12 • Chief cells- (peptic cells) release digestive enzymes

16. Stomach • Releases pepsinogen which becomes pepsin from HCl • Digests most dietary proteins • All three cell secretions together create gastric juice • Gastric lipase is a weak secretion that breaks down fats

17. Stomach • Regulation: • Cholecystokinn (from intestine), intestinal somatostatin, urogastrone • Acetylcholine from nerve endings • Parasympathetic impulses release gastrin • Both of these release histamine from mucous cells which stimulates gastric secretion

18. Stomach • Gastric secretion occurs in three phases: • Cephalic- sight, taste, smell, or thought of food releases gastric secretions • Gastric- Food in stomach releases gastrin • Intestinal- small intestine releases intestinal gastrin which increases gastric juice secretion

19. Stomach • Absorption: • Not very effective at absorbing • water, some salts, lipid-soluble drugs, and alcohol • Mixing and Emptying: • Chyme produced from mixing • Peristalsis pushes it to pyloric sphincter which causes it to relax • Length of time in stomach depends: • Liquids very rapid, fats long, proteins quick, carbohydrates very quick

20. Liver • Location/Background • Angiotensinogen • Thrombopoietin • Hepcidin • Betatrophin • Structure • Functions • Produces • Metabolic Activities • Stores

21. Bile • Background • Contains

22. Gallbladder • Location/Background • Structure • Functions • Storage • Bile salts • Chyme

23. Pancreas • Location • Structure • Secretions • Pancreatic Juices • Contains… • Enzymes • Nuclei • Amylase • Lipase • Trypsin • Chymotrypsin • Carboxytrypsin • They digest…

24. Small Intestine • The small intestine is about six meters long and contributes to digestion, absorption, and transportation • Contains three parts: • Duodenum- shortest part and is responsible for most chemical digestion • Contains a large amount of mucus secreting cells and receives digestion aid from pancreas and liver

25. Small Intestine • Jejunum- Contains most of the absorption. Villi and microvilli absorb what the body needs • Ileum- Primarily absorbs B12 and bile salts. Also absorbs anything the jejunum missed

26. Small Intestine • Secretions: • Secretin- in duodenum • Motilin- also in duodenum • Peptidase- breaks down peptides into amino acids • Sucrase, maltase, lactase- break down disaccharides into monosaccharides • Intestinal lipase- breaks down fatty acids and glycerol • Enterokinase- Shortens trypsinogen and trypsin • Regulation: • Direct contact with chyme stimulates secretions, parasympathetic reflexes trigger secretions as well

27. Small Intestine • Absorption: • Carbohydrates are absorbed by both facilitated diffusion and active transportation through villi • Proteins are broken down into amino acids and are absorbed into villi by active transportation

28. Small Intestine • Fat molecules are absorbed in several steps: • Fatty acid diffuses through villi • Resynthesized into previously digested forms • Encased in proteins • Large molecules of lipoprotein called chylomicrions go to lacteals of the villi • Molecules are emptied into the lymphatic system

29. Small Intestine • Water and electrolytes such as sodium and potassium are absorbed • Movement: • Peristalsis occurs along with segmentation • Segmentation- ring like contractions that cut chyme into segments and slow its movements • Parasympathetic impulses enhance movement and sympathetic impulses inhibit movement

30. Large Intestine • Contains several parts: • Cecum, colon, rectum, and anal canal • Colon divided as well: • Ascending, transverse, descending, and sigmoid colons

31. Large Intestine • Function: • Very little digestion • Secrete large amounts of mucus regulated by chyme and parasympathetic impulses • Absorption limited to water and certain ions such as sodium • Bacteria is prevalent and can aid in digestion of certain substances

32. Large Intestine • Movement: • Mainly relies on peristalsis but is much slower. Generally only two to three mass movements per day • Rectum: • Feces enters the rectum which causes the defecation reflex to occur • Peristalsis movements increase, the glottis closes and the diaphragm lowers • The external anal sphincter is signaled to relax and feces is forced out

33. Works Cited • www.meritnation.com • www.studyblue.com • www.pray40.com • www.academic.amc.edu • www.entertainment.howstuffworks.com • http://www.dietdoctor.com/restoring-liver-function-lchf • http://hepatitisctreatsment.blogspot.com/2014/11/liver-disease.html • http://galleryhip.com/bile.html • http://www.webmd.com/digestive-disorders/picture-of-the-gallbladder • http://www.merriam-webster.com/dictionary/chyme • http://www.uchospitals.edu/online-library/content=CDR62957 • http://upload.wikimedia.org/wikipedia/commons/7/77/Blausen_0817_SmallIntestine_Anatomy.png • http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/GutHormones.html • https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-physiology-textbook/the-digestive-system-23/phases-of-digestion-226/hormones-of-the-digestive-system-1110-6772/