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Chapter 7

Chapter 7. Anatomy and Physiology 7:11 Digestive System DHO 7 th edition. 7:11 Digestive System. Also known as the gastrointestinal system Responsible for Physical and chemical breakdown of food for use by the body System consists of the alimentary canal and the accessory organs.

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Chapter 7

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  1. Chapter 7 Anatomy and Physiology 7:11 Digestive System DHO 7th edition

  2. 7:11 Digestive System • Also known as the gastrointestinal system • Responsible for • Physical and chemical breakdown of food for use by the body • System consists of the alimentary canal and the accessory organs

  3. Alimentary Canal • Long muscular tube that begins at the mouth and ends at the anus, includes: • Mouth (oral cavity) • Pharynx • Esophagus • Stomach • Small intestine • Large intestine • Anus • Accessory organs: salivary glands, tongue, teeth, liver, gallbladder, pancreas

  4. Mouth, Buccal, or Oral Cavity • Receives food as it enters the body • Actions in the mouth • Food is tasted, broken down by the teeth, lubricated and partially digested by saliva, and swallowed • Teeth • Break down food by chewing and grinding • Process called mastication • Tongue • Muscular organ • Contains specialized receptors called taste buds • Allow us to taste sweet, sour, salty and bitter sensations

  5. Mouth, Buccal, or Oral Cavity (cont.) • Hard palate • Bony structure that forms roof of mouth • Separates mouth from nasal cavities • Soft palate • Posterior to hard palate • Separates mouth from nasopharynx • Uvula is a cone-shaped muscular structure • Located in middle of soft palate • Prevent food from entering nasopharynx during swallowing

  6. Mouth, Buccal, or Oral Cavity (cont.) • Salivary glands • Three pairs • Parotid • Sublingual • Submandibular • Produce saliva

  7. Mouth, Buccal, or Oral Cavity (cont.) • Saliva • Lubricates mouth during speech and chewing • Moistens food – easier to swallow • Contains an enzyme called salivary amylase • Begins chemical breakdown of carbohydrates, or starches, into sugars that can be taken into the body • Bolus • Term used to describe chewed food mixed with saliva • When swallowed, enters pharynx

  8. Pharynx • Carrier for both air and food • Carries food bolus to the esophagus • When bolus swallowed, muscle action causes epiglottis to close to prevent food from entering respiratory tract

  9. Esophagus • Muscular tube dorsal to the trachea • Carries bolus to stomach • Peristalsis, a rhythmic wavelike involuntary movement of the muscles, moves food toward stomach • Peristalsis occurs in rest of digestive tract, moving food in a forward direction • http://www.youtube.com/watch?v=YJ34Qx6hzJk

  10. Stomach • An enlarged portion of the alimentary canal • Receives food from esophagus • Mucous membrane lining contains rugae (folds) to increase surface area • Rugae disappear as stomach expands • Cardiac sphincter • Circular muscle between esophagus and stomach • Closes after food enters stomach to prevent it from going back into esophagus • Pyloric sphincter • Circular muscle between stomach and small intestine • Prevents food from entering small intestine until it is ready • Food usually remains in stomach about 2–4 hours

  11. Stomach • Gastric juices • Produced by glands in stomach • Converts food into semifluid material, called chyme • Contain hydrochloric acid and enzymes • Hydrochloric acid • Kills bacteria • Facilitates iron absorption • Activates the enzyme pepsin • Enzymes in gastric juices • Lipase – starts chemical breakdown of fats • Pepsin – starts protein digestion • Rennin – only present in infants, not adults, to help digest milk

  12. Small Intestine • About 20 feet long; 1 inch in diameter • Receives food from the stomach in the form of chyme • Small intestine divided into 3 sections • Duodenum • First 9-10 inches • Bile, from the gallbladder and liver, and pancreatic juice, from the pancreas, enter this section • Jejunum • Middle section of small intestine • About 8 feet in length • Ileum • Final 12 feet of the small intestine • Connects with the large intestine at the cecum (continues)

  13. Small Intestine(continued) • Process of digestion is completed in the small intestine • Products of digestion are absorbed into the blood stream for use by the body cells • Intestinal juices (produced by the small intestine) • Contain enzymes maltase, sucrase and lactase which break down sugars into simpler forms • Contain enzymes known as peptidases with complete the digestion of proteins • Contains enzymes steapsin (lipase) which aid in the digestion of fats

  14. Small Intestine(continued) • Bile • Emulsifies (physically breaks down) fats • Pancreatic juice • Contain enzymes that complete process of digestion • Amylase or amylopsin (act on sugars) • Trypsin and chymotrypsin ( act on proteins) • Lipase or steapsin (acts on fats)

  15. Small Intestine(continued) • Villi • Fingerlike projections on walls of intestine • Contain blood capillaries and lacteals • Capillaries absorb digested nutrients and carry them to the liver - they are either stored or released into the general circulation for use by the body cells • Lacteals absorb most of the digested fats and carry them to the thoracic duct in the lymphatic system, which releases them into the circulatory system • When food has finished its journey through the small intestine, only wastes, indigestible materials, and excess water remain

  16. Large Intestine Final section of the alimentary canal • About 5 feet long; 2 inches in diameter • Functions • Absorption of water and any remaining nutrients • Storage of indigestible materials before they are eliminated from the body • Synthesis (formation) and absorption of some B-complex vitamins and vitamin K by bacteria present in the intestine • Transportation of waste products out of the alimentary canal

  17. Large Intestine (continued) Divided into a series of connected sections • Cecum • First section that is connected to the ileum of the small intestine • Contains a circular muscle, the ileocecal valve, which prevents food from returning to the ileum • Also contains a small projection called the vermiform appendix

  18. Large Intestine (continued) • Colon • Next section of large intestine • Has several divisions • Ascending colon continues up the right side of the body • Transverse colon extends across the abdomen, below the liver and stomach above the small intestine • Descending colon extends down the left side of the body • Contacts to the sigmoid colon, an s-shaped section that joins the rectum

  19. Large Intestine (continued) • Rectum • Final 6-8 inches • Storage area for indigestible and wastes • Has a narrow canal, the anal canal, which opens to the anus (hole) • Fecal material, or stool, is the final waste product of the digestive process • Expelled through this opening

  20. Accessory Organs • Liver • Gallbladder • Pancreas

  21. Liver • Largest gland in the body • Accessory organ for digestive system • Location • Under the diaphragm in upper right quadrant of the abdomen Functions • Secretes bile, used to emulsify fats • Bile also makes fat water soluble which is necessary for absorption • Stores sugar in the form of glycogen • Glycogen is converted to glucose and released into bloodstream when needed

  22. Liver (continued) • Stores iron and certain vitamins • Produces heparin which prevents clotting of blood • Produces blood proteins, such as fibrinogen and prothrombin which aid in clotting • Produces cholesterol • Detoxifies (makes less harmful) substances • Destroys bacteria taken into blood from the intestine

  23. Healthy liver

  24. Gallbladder • Small muscular sac • Location – under the liver, attached to it by connective tissue • Function • Stores and concentrates bile it receives from the liver • Bile needed to emulsify fats • When bile is needed, gallbladder contracts and pushes bile through cystic duct into the common bile duct • Common bile duct drains into the duodenum

  25. Pancreas • Fish-shaped glandular organ located behind the stomach • Produces pancreatic juices to digest food • Enters duodenum through pancreatic duct • Produces insulin which is secreted into the blood stream • Insulin regulates metabolism (burning) of carbohydrates to convert glucose (blood sugar) to energy

  26. Diseases and Abnormal Conditions • Appendicitis • Cholecystitis • Cirrhosis • Constipation • Diarrhea • Diverticulitis • Gastroenteritis • Hemorrhoids • Hepatitis • Hernia • Pancreatitis • Peritonitis • Ulcer • Ulcerative Colitis

  27. Appendicitis • Acute inflammation of the appendix • Usually result from obstruction or infection • Symptoms • Generalized abdominal pain, later localizes to lower right quadrant • Nausea and vomiting • Mild fever • Elevated wbc count • Treated by appendectomy (surgical removal of appendix • If appendix ruptures, infectious material spills into peritoneal cavity – peritonitis (very serious condition)

  28. Cholecystitis • Inflammation of the gallbladder • If gallstones (crystallized cholesterol, bile salts, and bile pigments) – known as cholelithiasis • Symptoms • Indigestion – usually occurs after eating fatty foods • Nausea and vomiting • Pain under the rib cage that radiates to right shoulder • If bile duct gets blocked, gallbladder can rupture and cause peritonitis • Treatment • Low-fat diet, lithotripsy (shock waves to shatter stones), cholecystectomy (surgical removal)

  29. Cirrhosis • Chronic destruction of liver cells accompanied by the formation of fibrous connective and scar tissue • Causes • Hepatitis • Bile duct disease • Chemical toxins • Malnutrition associated with alcoholism

  30. Cirrhosis (cont.) • Symptoms vary – become more severe as it progresses • Liver enlargement • Hematemesis (vomiting blood) • Anemia • Nosebleeds • Indigestion • Jaundice (yellow discoloration) • Nausea • Ascites (fluid accumulation in peritoneal cavity) • Edema in the lower extremities • When liver fails • Disorientation • Hallucinations • Hepatic coma • Death

  31. Cirrhosis (cont.) • Treatment • Directed toward preventing further damage • Alcohol avoidance • Proper nutrition • Vitamin supplements • Diuretics • Rest • Infection prevention • Appropriate exercise • Liver transplant

  32. Constipation • Fecal material remains in colon too long • Excessive reabsorption of water occurs • Causes • Poor bowel habits • Chronic laxative use – lead to “lazy” bowel • Low fiber diet • Certain digestive diseases • Treatment • High fiber diet • Adequate fluids • Exercise

  33. Diarrhea • Frequent watery stools • Causes • Infection • Stress • Diet • Irritated colon • Toxic substances • Extremely dangerous in infants and small children because of excessive fluid loss • Treatment • Eliminate cause • Provide adequate fluid intake • Modify the diet

  34. Diverticulitis • Inflammation of the diverticula, pouches (or sacs) that form in the intestine as the mucosal lining pushes through the surrounding muscle • Fecal material and bacteria become trapped, inflammation occurs • Can result in rupture of sac, leading to peritonitis

  35. Diverticulitis (cont.) • Symptoms • Vary according to amount of inflammation • Abdominal pain • Irregular bowel movements • Flatus (gas) • Constipation or diarrhea • Abdominal distention • Low-grade fever • Nausea and vomiting • Treatment • Antibiotics • Stool softening medications • Pain meds • High fiber diet • Possible surgery to remove affected section of colon

  36. Diverticulosis vs. Diverticulitis

  37. Gastroenteritis • Inflammation of the mucous membrane that lines the stomach and intestinal tract • Causes • Food poisoning • Infection • Toxins • Symptoms • Abdominal cramping • Nausea & vomiting • Fever • Diarrhea • Treatment • Rest • Increased fluid intake • If severe • Antibiotics • IV fluids • Medications to slow peristalsis

  38. Hemorrhoids • Painful dilated or varicose veins of the rectum or anus • Causes • Straining to defecate • Constipation • Pressure during pregnancy or labor • Insufficient fluid intake • Laxative abuse • Prolonged sitting or standing • Symptoms • Pain • Itching • Bleeding • Treatment • High-fiber diet • Increased fluid intake • Stool softeners • Sitz baths or warm moist compresses • Hemorrhoidectomy

  39. Hemorrhoids (Diagram)

  40. Hepatitis • Viral inflammation of the liver • Types of hepatitis viruses • Hepatitis A • Highly contagious • Transmitted via contaminated food or water • Vaccine available • Hepatitis B • Serum hepatitis • Transmitted via body fluids (blood, serum, saliva, urine, semen, vaginal secretions, breast milk) • More serious than Hepatitis A • Can lead to chronic hepatitis or cirrhosis of the liver • Vaccine available (recommended for all health care workers)

  41. Hepatitis (cont.) • Hepatitis C • Transmitted and spread through body fluids • Main methods of transmission • Sharing needles while injecting drugs • Accidental needle stick with contaminated sharps at work • Passed from infected mother to infant during birth • Much more likely to progress to chronic hepatitis and/or cirrhosis • Hepatitis D and Hepatitis E are other strains indentified

  42. Hepatitis (cont.) • Symptoms • Fever • Anorexia • Nausea and vomiting • Fatigue • Dark-colored urine • Clay-colored stool • Myalgia • Enlarged liver • Jaundice • Treatment • Rest • High protein and calorie diet, low in fat • Liver transplant if liver is severely damaged

  43. Hernia • Rupture whereby an internal organ pushes through a weakened area or natural opening in a body wall • Hiatal hernia • Stomach protrudes through the diaphragm and into the chest cavity through the opening for the esophagus • Inguinal hernia • Section of small intestine protrudes through the inguinal rings of the lower abdominal wall

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