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The Digestive System What happens to what we eat ??

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Presentation on theme: "The Digestive System What happens to what we eat ??"— Presentation transcript:

1 The Digestive System What happens to what we eat ??

2 Introduction Principal structure: GI tract also called alimentary tube/canal Principal structure: GI tract also called alimentary tube/canal Hollow tube 29 feet long in average adult Hollow tube 29 feet long in average adult General functions: General functions: Digestion mechanical & chemical food breakdown & Absorption of nutrients Digestion mechanical & chemical food breakdown & Absorption of nutrients Elimination of waste Elimination of waste

3 Name that organ …

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5 Primary Organs of Digestion  Mouth  pharynx  esophagus  stomach  small intestine (duodenum,jejunum,ileum)  large intestine (cecum ascending, transverse descending, sigmoid)  rectum  anal canal

6 Accessory Organs teeth teeth tongue tongue salivary glands salivary glands liver liver gall bladder gall bladder pancreas pancreas appendix appendix Salivary glands : parotid, submandibular, sublingual Salivary glands : parotid, submandibular, sublingual

7 Gastric Disorders Disorders affecting the organs of the digestive system Disorders affecting the organs of the digestive system Can you name a few??? Can you name a few???

8 Mechanism of Disease 1. Primary digestive organ affected 2. S/S 3. Dx/tests 4. Treatments 5. How is digestive SYSTEM affected? Homeostasis altered?

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12 Digestive Tract Wall Layers 4 layers found within the lumen of the entire digestive tract but specific tissue type comprising each layer can vary from organ to organ 4 layers found within the lumen of the entire digestive tract but specific tissue type comprising each layer can vary from organ to organ Serosa: outermost, covers outside of dig organs. Attaches dig tract to wall of abdominal pelvic cavity by forming folds called mesenteries Serosa: outermost, covers outside of dig organs. Attaches dig tract to wall of abdominal pelvic cavity by forming folds called mesenteries Muscularis: 2-3 layers of smooth muscular tissue Muscularis: 2-3 layers of smooth muscular tissue Submucosa: connective tissue Submucosa: connective tissue Mucosa: innermost, epithelial tissue Mucosa: innermost, epithelial tissue

13 Peritoneum Serous membrane lining the abdominal cavity & covers most digestive organs Serous membrane lining the abdominal cavity & covers most digestive organs Parietal layer: lines abd. Cavity Parietal layer: lines abd. Cavity Visceral layer: covers organs Visceral layer: covers organs Peritoneal space: between 2 layers which contains peritoneal fluid (lubes for breathing and digestive movements) Peritoneal space: between 2 layers which contains peritoneal fluid (lubes for breathing and digestive movements)

14 Extensions Extensions of peritoneum serve to suspend organs in abd cav : carry nerves/bld vessels to organs. Extensions of peritoneum serve to suspend organs in abd cav : carry nerves/bld vessels to organs. Mesentary: Fan shaped extension between the parietal and visceral layers of peritoneum; anchors sm intestine to posterior abd wall Mesentary: Fan shaped extension between the parietal and visceral layers of peritoneum; anchors sm intestine to posterior abd wall Greater omentum: Apron shaped pouchlike extension of visceral peritoneum from stomach, duodenum & transverse colon Greater omentum: Apron shaped pouchlike extension of visceral peritoneum from stomach, duodenum & transverse colon

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16 Peritonitis: inflammation (usually bacterial) of peritoneum Peritonitis: inflammation (usually bacterial) of peritoneum Ascites: accumulation of fluid in peritoneal space Ascites: accumulation of fluid in peritoneal space

17 Mouth and Teeth Oral cavity; lined w/ mucous membrane Oral cavity; lined w/ mucous membrane Parts: Parts: Hard Palate: anterior bony structure on roof of mouth Soft palate: posterior to hard palate; made of muscular tissue Hard Palate: anterior bony structure on roof of mouth Soft palate: posterior to hard palate; made of muscular tissue Teeth 20 deciduous 32 permanent Teeth 20 deciduous 32 permanent

18 Uvula: cone shaped process, extending from soft palate; prevents liquids from entering nasal cavity, directs food down Uvula: cone shaped process, extending from soft palate; prevents liquids from entering nasal cavity, directs food down Tongue: skeletal muscle covered with mucous membrane, anchored by hyoid bone Tongue: skeletal muscle covered with mucous membrane, anchored by hyoid bone Frenulum: attaches tongue to floor of mouth Frenulum: attaches tongue to floor of mouth

19 3 Salivary Glands 3 pairs secrete 1L of saliva daily 3 pairs secrete 1L of saliva daily How by way of ducts that carry it to digestive tract How by way of ducts that carry it to digestive tract Parotids: largest, located below ears Parotids: largest, located below ears Submandibulars: post corners of mandible Submandibulars: post corners of mandible Sublinguals: below floor of mouth Sublinguals: below floor of mouth

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21 Saliva: mostly H2O which helps dissolve food for tasting and moisten it for swallowing Saliva: mostly H2O which helps dissolve food for tasting and moisten it for swallowing Contain mucous and digestive enzyme salivary amylase which begins process of chemical breakdown of food Contain mucous and digestive enzyme salivary amylase which begins process of chemical breakdown of food

22 Pharynx Organ of respiratory &digestive system Organ of respiratory &digestive system Swallowing (deglutition) is reflexive and controlled by medulla. Swallowing (deglutition) is reflexive and controlled by medulla. Esophagus Esophagus Muscular tube lined w/ mucous membrane Muscular tube lined w/ mucous 10” long Posterior to 10” long Posterior to trachea Passageway for food Passageway for food Junction of stomach : lower espohageal sphincter (LES) contracts prevents backup of stomach contents into esophagus Junction of stomach : lower espohageal sphincter (LES) contracts prevents backup of stomach contents into esophagus

23 Esophageal inflamm d/t GERD

24 Stomach Stomach Inferior to diaphragm; “C” shaped in LUQ, Inferior to diaphragm; “C” shaped in LUQ, Stomach secretes both gastric acid (HCl and enzymes) and mucus (for self protection) pH: 1-2, necessary for enzyme (pepsin) function and kills pathogens pH: 1-2, necessary for enzyme (pepsin) function and kills pathogens Temporary store for food which is also churned by 3 muscular layers to form chyme; a creamy semi-solid substance Temporary store for food which is also churned by 3 muscular layers to form chyme; a creamy semi-solid substance

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26 Gastric Disorders Gastritis: inflammation of stomach lining; acute or chronic Gastritis: inflammation of stomach lining; acute or chronic Pyloric stenosis Pyloric stenosis Ulcer: cause: helicobacter pylori bacterium. Peptic or duodenal Ulcer: cause: helicobacter pylori bacterium. Peptic or duodenal Hiatal Hernia: stomach protrudes thru diaphragm Hiatal Hernia: stomach protrudes thru diaphragm Stomach CA Stomach CA Food Poisoning: eschericia coli common cause Food Poisoning: eschericia coli common cause

27 Small Intestine Small 20 feet long; smaller diameter than large 20 feet long; smaller diameter than large intestine. 3 parts: duodenum, jejunum, ileum 3 parts: duodenum, jejunum, ileum Digestion completed in small intestine. End products of digestion are absorbed into blood/lymph Digestion completed in small intestine. End products of digestion are absorbed into blood/lymph 1000s of internal glands w/in the mucous membrane lining secrete digestive juices aids the chemical breakdown of chyme 1000s of internal glands w/in the mucous membrane lining secrete digestive juices aids the chemical breakdown of chyme

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29 Small Intestine Disorders Enteritis inflammation of small intestine Enteritis inflammation of small intestine Malabsorption Syndrome: failure to absorb nutrients Malabsorption Syndrome: failure to absorb nutrients

30 Large Intestine Large Intestine 5 ft 2.5” diameter 5 ft 2.5” diameter Extends from ileum to anus. Extends from ileum to anus. Divisions: cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anal canal Divisions: cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anal canal Passage of material takes 3-5 days Passage of material takes 3-5 days Functions: absorps H2O, minerals, vits Functions: absorps H2O, minerals, vits eliminate indigestible material eliminate indigestible material Undigested, unabsorbed food ( chyme) changes to consistency of fecal matter here as H2O and salts are reabsorbed Undigested, unabsorbed food ( chyme) changes to consistency of fecal matter here as H2O and salts are reabsorbed

31 Large Intestine Disorders IBS: intermittent constipation/diarrhea. Often d/t food sensitivity, inflammation, genetics. Rarely serious IBS: intermittent constipation/diarrhea. Often d/t food sensitivity, inflammation, genetics. Rarely serious Colitis: general name for any inflammation of lg int. Generally, inflammation/ulceration of rectum or small sections of colon Colitis: general name for any inflammation of lg int. Generally, inflammation/ulceration of rectum or small sections of colon Crohn’s Disease: inflammation /ulceration may be accompanied by strictures of intestines **often affects small intestine Crohn’s Disease: inflammation /ulceration may be accompanied by strictures of intestines **often affects small intestine Colorectal CA Colorectal CA Diverticulitis: inflammation of abnormal outpouching of int. (grape like structures) Diverticulitis: inflammation of abnormal outpouching of int. (grape like structures)

32 Intestinal Disorders Paralytic ileus: cessation of smooth muscle contraction of intestine. Etiology. Surgical complication or due to inflammation/peritonitis Paralytic ileus: cessation of smooth muscle contraction of intestine. Etiology. Surgical complication or due to inflammation/peritonitis Bowel Obstruction: caused by many conditions. s/s: pain, nvd, abd distention Bowel Obstruction: caused by many conditions. s/s: pain, nvd, abd distention Intussusception: telescoping of intestine Intussusception: telescoping of intestine

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34 Liver/Gall Bladder Liver/Gall Bladder Located in RUQ Located in RUQ Liver: largest gland in the body Liver: largest gland in the body Exocrine gland: secretes bile Exocrine gland: secretes bile Has two major blood vessels: hepatic artery & portal vein Has two major blood vessels: hepatic artery & portal vein Liver cells many functions but digestive function is the production of bile Liver cells many functions but digestive function is the production of bile GB a small sac on undersurface of liver concentrates & stores bile produced in liver GB a small sac on undersurface of liver concentrates & stores bile produced in liver

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36 Bile Composition mostly H2O. Composition mostly H2O. Excretory function: carries billirubin and excess cholesterol to intestine for elimination in feces Excretory function: carries billirubin and excess cholesterol to intestine for elimination in feces Digestive function accomplished by bile salts which emulsify fats in small intestine Digestive function accomplished by bile salts which emulsify fats in small intestine Production of bile stimulated by hormone (secretin)which is produced by duodenum when food enters small int Production of bile stimulated by hormone (secretin)which is produced by duodenum when food enters small int

37 Bile collects in bile caps w/in liver, which merge to form bile ducts that drain into R & L hepatic ducts, which in turn merge to form the common hepatic duct The cystic duct (from GB) joins with the common hepatic duct to form the common bile duct Bile can drain directly into the duod via the common bile duct or be temporarily stored in the GB via the cystic duct The common bile duct and the pancreatic duct enter the duodenum together at the Ampulla of Vater. The branchings of the bile ducts are called the "biliary tree"

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39 Liver/GB Disorders Cholelithiasis: gallstones; silent or symptomatic occurs when bile has high conc of chol Cholelithiasis: gallstones; silent or symptomatic occurs when bile has high conc of chol Cholecystitis Cholecystitis In a cholecystectomy the hepatic duct is connected directly to the common bile duct and dilute bile flows into duod In a cholecystectomy the hepatic duct is connected directly to the common bile duct and dilute bile flows into duod Jaundice and biliary colic Jaundice and biliary colic Hepatitis: virus causes inflamm &liver damage Hepatitis: virus causes inflamm &liver damage

40 Liver GB Disorders Cirrhosis: liver scarring d/t etoh, hepatitis virus or other viral organisms Cirrhosis: liver scarring d/t etoh, hepatitis virus or other viral organisms Portal Htn: ^ b/p in blood vessels supplying liver distends veins in esophagus and stomach; complication of cirrhosis (esophageal varices) Portal Htn: ^ b/p in blood vessels supplying liver distends veins in esophagus and stomach; complication of cirrhosis (esophageal varices)

41 Gallstones

42 10. Pancreas Location LUQ Retroperitoneal organ located posterior to the stomach on the posterior abdominal wall Location LUQ Retroperitoneal organ located posterior to the stomach on the posterior abdominal wall Two functions: Two functions: Exocrine glands: produce pancreatic juice containing digestive enzymes Exocrine glands: produce pancreatic juice containing digestive enzymes Endocrine glands: produce insulin and glucagon Endocrine glands: produce insulin and glucagon Main source of enzymes for digesting lipids and proteins - the intestinal walls have enzymes that digest CHO Main source of enzymes for digesting lipids and proteins - the intestinal walls have enzymes that digest CHO

43 Pancreas (stomach removed)

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45 Pancreatic secretions accumulate in intralobular ducts that drain to the main pancreatic duct, which drains directly into the duodenum Pancreatic secretions accumulate in intralobular ducts that drain to the main pancreatic duct, which drains directly into the duodenum Digestive enzymes: Digestive enzymes: Amylase: digests starch to maltose; backup to salivary amylase Amylase: digests starch to maltose; backup to salivary amylase Lipase: converts fats to fatty acids and glycerol Lipase: converts fats to fatty acids and glycerol Trypsinogen: inactive enzyme that activates in duodenum to trypsin which digests polypeptides to amino acids Trypsinogen: inactive enzyme that activates in duodenum to trypsin which digests polypeptides to amino acids

46 Pancreatic Disorders Pancreatitis: usually due to duct blockage Pancreatitis: usually due to duct blockage Pancreatic CA Pancreatic CA Cystic Fibrosis: thickened secretions block flow Cystic Fibrosis: thickened secretions block flow

47 11. Appendix No digestive function No digestive function Contains lymph tissue and may have minor immune function Contains lymph tissue and may have minor immune function Loc in RLQ and opens into the cecum and the lumen of this opening is larger in pediatrics and may be completely closed in geriatrics Loc in RLQ and opens into the cecum and the lumen of this opening is larger in pediatrics and may be completely closed in geriatrics

48 So how does it all work ! The digestive system prepares food for use by hundreds of millions of body’s cells. The digestive system prepares food for use by hundreds of millions of body’s cells. Food when eaten cannot reach cells because it cannot pass through the intestinal walls to the bloodstream and, if it could it would not be in a useful chemical state. Food when eaten cannot reach cells because it cannot pass through the intestinal walls to the bloodstream and, if it could it would not be in a useful chemical state.

49 The gut modifies food physically and chemically and disposes of unusable waste The gut modifies food physically and chemically and disposes of unusable waste Physical and chemical modification (digestion) depends on exocrine and endocrine secretions and controlled movement of food through the digestive tract. Physical and chemical modification (digestion) depends on exocrine and endocrine secretions and controlled movement of food through the digestive tract.

50 Digestion, Absorption Metabolism Food undergoes 3 types of processing: digestion, absorption and metabolism Food undergoes 3 types of processing: digestion, absorption and metabolism Digestion: altering of the physical composition of food for absorption & use by the body’s cells Digestion: altering of the physical composition of food for absorption & use by the body’s cells Absorption: passage of food molecules through internal membrane to bloodstream for use by body’s cells Absorption: passage of food molecules through internal membrane to bloodstream for use by body’s cells Digestion & absorption performed by digestive system Digestion & absorption performed by digestive system Metabolism: use of various by-products from digestive processes for chemical cellular processes; performed by all body cells Metabolism: use of various by-products from digestive processes for chemical cellular processes; performed by all body cells

51 Digestion Mechanical: breaks food into smaller pieces, mixes it w/ digestive juices, moves it along alimentary canal and eliminates waste Mechanical: breaks food into smaller pieces, mixes it w/ digestive juices, moves it along alimentary canal and eliminates waste Chemical: breaks down food into absorbable molecules able to pass thru internal mucosa into circulatory system Chemical: breaks down food into absorbable molecules able to pass thru internal mucosa into circulatory system 3 primary types of substances that are digested: carbs, proteins, fats 3 primary types of substances that are digested: carbs, proteins, fats

52 What is an enzyme? Much of the work of the digestive tract is accomplished by enzyme activity Much of the work of the digestive tract is accomplished by enzyme activity Enzyme: biological catalyst. Necessary for chemical digestion Enzyme: biological catalyst. Necessary for chemical digestion Most enzymes are proteins Most enzymes are proteins Each enzyme has specific shape due to folding/looping of amino acid chains Each enzyme has specific shape due to folding/looping of amino acid chains Substrate (subs to be altered) fits into part of the enzyme called the active site Substrate (subs to be altered) fits into part of the enzyme called the active site Enzyme itself does not change but it changes the substrate Enzyme itself does not change but it changes the substrate

53 Carb Digestion Mainly occurs in small intestine Mainly occurs in small intestine Pancreatic enzyme: amylase breaks CHO(carbohydrates) into simpler maltose Pancreatic enzyme: amylase breaks CHO(carbohydrates) into simpler maltose Intestional enzymes: maltase, sucrase and lactase break down CHO into simpler sugars, primarily glucose Intestional enzymes: maltase, sucrase and lactase break down CHO into simpler sugars, primarily glucose

54 Protein Digestion Begins in stomach where Pepsin, enzyme in gastric juice, along w/ HCl simplifies protein molecule Begins in stomach where Pepsin, enzyme in gastric juice, along w/ HCl simplifies protein molecule In small intestine, trypsin from pancreatic juice and peptidase from intestinal juice break down the smaller protein molecules into amino acids In small intestine, trypsin from pancreatic juice and peptidase from intestinal juice break down the smaller protein molecules into amino acids

55 Fat Digestion Fat is emulsified in duodenum by bile Fat is emulsified in duodenum by bile Then, pancreatic lipase breaks down fat molecules into fatty acids and glycerol Then, pancreatic lipase breaks down fat molecules into fatty acids and glycerol


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