Digestive System

1. Digestive System

2. Digestion • the organic process by which food is converted into substances that can be absorbed into the body • Google on-line dictionary

5. Alimentary Tract • Also known as the Digestive Tract or GI (gastrointestinal) tract • This is the tube in which food is digested & broken down into energy • Consists of the: • Mouth • Pharynx • Esophagus • Stomach • Small intestines • Large intestines • Anus

6. Accessory Organs • These are organs that are not within the alimentary tract but contribute to digestions • Tongue • Teeth • Salivary glands • Pancreas • Liver • Gallbladder

7. Alimentary Tract • The “tube” is made up of four layers of tissue • Mucosa • Epithelial tissue; secretes mucous & some digestive juices • Submucosa • Connnective tissue; blood vessels & nerves • Muscularis • Circular muscles • Scrosa • Longitudinal muscles

8. Abdominal Cavity • Peritoneum • Serous membrane that lines the cavity • Outer – Parietal • Inner – Visceral (What other cavity has the same linings?) • Mesentery – attach to posterior wall of cavity • Small intestines attach • Greater Omentum – attach to anterior wall • Double layer; contains fat; apron

11. Types of Digestion • Mechanical – physical breakdown of food • Chewing – mastication • Peristalsis • Chemical – complex compounds broken down into simpler compounds • Digestive enzymes • Starch Glucose • Protein Amino Acids • Fat Emulsified Fat

12. Parts of the Alimentary Tract • Mouth – Buccal Cavity (Oral Cavity) • Accessory organs in Mouth • Teeth • 20 baby teeth (Deciduous) • 32 Adult teeth (Permanent) • Tongue • Skeletal muscle • Papillae – taste buds (Where are they located?) • 1st step in swallowing • Salivary Glands

14. Salivary Glands • 3 locations • Parotid • Submandibular • Sublingual • Secrete Saliva • Continuous • Food increases the production • Smell increases production

15. Saliva • Consists mostly of H2O • Dissolves food • Moistens food for swallowing • Contain amylase to aid in breaking down food • Ptyalin – breaks complex sugar to glucose or maltose • Made from blood plasma • Contain albumin, WBC, etc.

16. Esophagus • Tube that connects mouth to stomach • 10 inches long • No digestion takes place • Food is in form of bolus • Peristalsis – the contraction to move food down the tube • Lower esophageal sphincter (cardiac sphincter) allows food into the stomach

18. Stomach • Which quadrant is it located? • Which region of the abdomen? • Reservoir for food • Mechanical digestion • Peristalsis to mix the food with gastric juice to make chyme • Chemical digestion • Gastric juice contains enzymes to begin food breakdown

19. Parts of the Stomach • Cardiac Sphincter – controls entrance to stomach • Greater curvature – outside curve • Lesser curvature – inside curve • Pyloric sphincter – controls exit to the duodenum • Rugae – folds of the mucosa

20. Gastric secreting cells (Gastric juice) • Found in the gastric pit • Enteroendocrine cells (G cells) – hormone gastrin • Mucous cells – secrete mucus • Protects the stomach lining from acid • Chief cells – secretes pepsinogen • Inactive pepsin • Parietal cells – secrete HCl (hydrochloric acid) • Proton pump – H+ & joined with Cl- in stomach • HCl converts pepsinogen to active pepsin • HCl make the stomach pH 1 or 2 (what is neutral?) (acid/base) • Acidity kills microorganisms • Secrete intrinsic factor (to absorb what vitamin?)

22. Small Intestines

23. Small Intestines • 20 feet long • 3 parts • Duodenum – 12 inches • Jejunum – 8 feet long • Ileum – 10 – 12 feet long

24. Absorption • Food is absorbed in the small intestines • Chyme enters into the small intestines, many enzymes are secreted • Enzymes come from the liver, pancreas, gallbladder • Sucrase, Maltase, & lactase – breaks down sugar (sucrose, maltose, & lactose) • Capillary network • Water soluable nutrients absorb into the capillary by active transport

25. Active Transport • Active transport involves the use of proteins that don't just passively facilitate the transport of substances across the cell membrane, but require the use of cellular energy(usually ATP) to actively pump substances into or out of the cell. • Monosacharides • Amino acids • Positive ions • Water – soluble vitamins

26. Absorption cont • Negative ions – absorbed passive & active • Water – absorbed by osmosis • Certain nutrients need special substances to be absorbed • B12 (intrinsic factor) • Ca+ (Vitamin D)

27. Lacteals – lymph vessels in the villi • Fat soluble vitamins & fats need bile salts • What are the fat soluble vitamins?

28. Pancreas • Feather shaped organ • Exocrine & endocrine organ • Secretes Pancreatic juice into the duodenum • Peptidase, trypsin, & protease – breakdown protein • Amylase – breakdown starch to glucose • Lipase & steapsin – breakdown fat to fatty acids & glycerol • Sodium bicarbonate – neutralize the chyme

30. Liver • Largest organ in body • makes bile • Bile emulsifies fat in smaller globule to enable lipase & steapsin to break it down • Stores excess sugar as glycogen • Detoxifies alcohol, drugs, & toxin • Prepares urea (main waste of protein metabolism) • Stores what fat soluble vitamins?

31. Liver – Which quadrant is it located?

32. Large Intestines (Colon) • 5 feet long • Chyme enters for water absorption (80%) • Also minerals & vitamins absorbed • Makes fesces (undigestible material) • Colonic mucus lubricates fesces for excretion • Makes fesces from waste; decreased water makes formed • Cecum • Appendix • Ascending colon • Transverse colon • Descending colon • Rectum • anus

33. Defecation • Elimination of Fesces • Contains • Normal: 3/day – 3/week • Rectum becomes distended and reflex is triggered • External anal sphincter relaxes • Can control the muscle • Continue to ignore the reflex urge then it will lessen or goes away

34. Gas formation • Flatulence • Normal: 1 – 3 pints of gas /day by rectum • Caused by swallowed air & breakdown of food • Smell: due to bacteria in colon • Gas causing foods: • Beans • Vegetables – broccoli & cabbage • Fruit • Whole grains • Milk & milk products • Artificial sweeteners (sorbitol)

35. Vomiting • Expulsion of stomach & intestinal contents • Causes • Irritation • Motion sickness • Food poisoning • Diseases • Controlled by the medulla of the brain

36. Pyloric stenosis • Opening of the pyloric sphincter is narrowed • Sphincter is enlarged • Found in infants – more common in males • Symptoms - vomiting

37. Appendicitis • Inflammation of the appendix • Ruptured appendix can lead to peritonitis (inflammation of the abdominal peritoneal cavity) • Symptoms • Abdominal pain • Nausea • Vomiting • Fever • Increased WBC • Know about McBurney’s Point

38. Diseases of the Gallbladder • All symptoms usually result after eating fatty foods • Cholecystitis • Inflammation of the gallbladder • Pain • Nausea & Vomiting • indigestion • Choleliathiasis • Crystalized bile forming stones in the gallbladder • Symptoms • Pain • N & V • indigestion

39. Constipation • Occurs when fecal matter remains in the colon too long • There is too much water absorbed & the fesces becomes hardened • Causes • Poor bowel habits • Chronic laxative use • Low fiber diet • Digestive system diseases

40. Diarrhea • Frequent watery stools • May lead to dehydration due to excess fluid loss • Causes • Infection • Stress • Diet • Irritated colon • Toxic substances

41. Cirrhosis • Chronic destruction of liver cells • Causes • Hepatitis • Chemical toxins • Malnutrition • alcoholism • Symptoms • N & V • Liver enlargement • Indigestion • Jaundice • hematemesis • Treatment – preventing further damage • NO cure