Digestive System

1. Digestive System CHAPTER 12

2. Digestive System Overview • Digestive System • Known as gastrointestinal tract • Also known as digestive tract or alimentary canal • Approximately 30 feet long • Begins with mouth (oral cavity), ends with anus • Functions • Prepare foods for absorption into the bloodstream • Prepare foods for use by the body cells • Responsible for elimination of solid wastes from the body

3. Digestive System Structures • Oral cavity (Buccal cavity) • Lips • Cheeks • Hard palate • Rugae • Soft palate • Uvula • Tongue • Principle organ of the sense of taste • Also assists in process of chewing (mastication) and swallowing (deglutition)

4. Digestive System Structures • Salivary glands • Three pairs • Parotids • Submandibulars • Sublinguals • Secrete saliva • Mostly water, but contains mucus and digestive enzymes that aid in digestive process • Digestive enzymes contained in saliva • Amylase – aids in digestion of carbohydrates • Lipase – aids in digestion of fats

5. Digestive System Structures • Pharynx • Known as the throat • Serves as passageway for both respiratory and digestive systems • Oropharynx • Section leading away from oral cavity • Nasopharynx • Behind nasal cavity • Laryngopharynx • Lower portion – opens into esophagus and larynx

6. Digestive System Structures • Esophagus • Receives food from pharynx and propels it to stomach • Cardiac sphincter (lower esophageal sphincter) controls passage of food from esophagus into the stomach • Relaxes = food enters stomach • Contracts = stomach contents prevented from reentering the esophagus

7. Digestive System Structures • Stomach • Fundus • Upper rounded portion • Body • Central part

8. Digestive System Structures • Stomach • Pylorus • Lower tubular part (also called the gastric antrum) • Pyloric sphincter regulates passage of food from stomach into the duodenum • Folds in mucous membranes of stomach = Rugae

9. Digestive System Structures • Stomach • Gastric juices breakdown food in stomach • Muscular action of stomach causes churning of food • Mixes food with the secretions • Chyme = liquidlike mixture of partially digested food and digestive secretions

10. Digestive System Structures • Small intestine • Approximately 20 feet long • Also known as the small bowel • Divided into three parts • Duodenum • Jejunum • Ileum

11. Digestive System Structures • Large intestine • Cecum • Appendix hangs from lower portion of cecum • Ascending colon • Hepatic flexure • Transverse colon • Splenic flexure • Descending colon • Sigmoid colon • Rectum • Anus

12. Accessory Organs of Digestion • Liver • Located immediately under diaphragm, slightly to the right • Only digestive function • Production of bile for emulsification of fats in small intestine

13. Accessory Organs of Digestion • Liver • Additional functions of liver • Excretion of bile pigments into bile • Synthesis of vitamin K-dependent plasma proteins • Amino acid metabolism • Carbohydrate metabolism • Fat metabolism • Phagocytosis • Detoxification • Storage of vital nutrients

14. Accessory Organs of Digestion • Gallbladder • Pear-shaped sac, located under surface of liver • Main function: • To store and concentrate bile produced by the liver • Releases bile in response to presence of fatty content of food present in duodenum • Emulsifies fats

15. Accessory Organs of Digestion • Pancreas • Located in upper left quadrant of abdomen, behind stomach • Functions as exocrine gland to manufacture digestive juices • Trypsin – breaks down proteins • Pancreatic lipase – breaks down fats • Pancreatic amylase – breaks down carbohydrates • Sodium bicarbonate – neutralizes acidic stomach contents

16. Accessory Organs of Digestion • Pancreas • Functions as endocrine gland to manufacture insulin and glucagon • Insulin – hormone that makes it possible for glucose to pass from blood through cell membranes to be used for energy • Insulin also promotes conversion of excess glucose into glycogen • Glucagon – hormone that stimulates the liver to convert glycogen into glucose in time of need

17. Accessory Organs of Digestion • Teeth • Primary responsibility • Chewing (mastication) • Food is ground by teeth and softened by saliva • Primary teeth = deciduous teeth • Set of 20 teeth – appears around age 6 months • Secondary teeth = permanent teeth • Begin to appear around age 6

18. Accessory Organs of Digestion • Teeth • Incisors • Chisel shape with sharp edges for biting food • Canine or cuspid teeth • Useful for grasping and tearing food • Bicuspids (premolars) and molars • Flat surfaces, multiple projections for crushing and grinding food

19. Accessory Organs of Digestion • Teeth • Crown • Visible part of the tooth • Covered with enamel – hardest substance in body • Neck • Lies just beneath the gum line • Root • Embedded in bony socket of the jaw bone • Root canal = pulp cavity • Central core of the tooth

20. Accessory Organs of Digestion Layers of Teeth

21. Common Signs and Symptoms • Achlorhydria • Abnormal condition characterized by the absence of hydrochloric acid in the gastric juice • Anorexia • Lack or loss of appetite, resulting in the inability to eat

22. Common Signs and Symptoms • Aphagia • Condition characterized by the loss of the ability to swallow as a result of organic or psychologic causes • Ascites • Abnormal accumulation of fluid within the peritoneal cavity • Fluid contains large amounts of protein and electrolytes

23. Common Signs and Symptoms • Borborygmus • An audible abdominal sound produced by hyperactive intestinal peristalsis • Borborygmi are rumbling, gurgling, and tinkling noises heard when listening with a stethoscope

24. Common Signs and Symptoms • Constipation • Difficulty in passing stools, or an incomplete or infrequent passage of hard stools • Diarrhea • Frequent passage of loose, watery stools

25. Common Signs and Symptoms • Dyspepsia • Vague feeling of epigastric discomfort after eating • Involves an uncomfortable feeling of fullness, heartburn, bloating, and nausea • Dysphagia • Difficulty in swallowing, commonly associated with obstructive or motor disorders of the esophagus

26. Common Signs and Symptoms • Emaciation • Excessive leanness caused by disease or lack of nutrition • Emesis • Material expelled from the stomach during vomiting • Vomitus

27. Common Signs and Symptoms • Eructation • Act of bringing up air from the stomach with a characteristic sound through the mouth • Belching • Flatus; Flatulence • Air or gas in the intestine that is passed through the rectum

28. Common Signs and Symptoms • Gastroesophageal Reflux • Backflow of contents of stomach into esophagus • Often result of incompetence of the lower esophageal sphincter • Icterus • A yellowish discoloration of the skin, mucous membranes, and sclera of the eyes, caused by greater than normal amounts of bilirubin in the blood • Also called jaundice

29. Common Signs and Symptoms • Melena • An abnormal, black, tarry stool containing digested blood • Nausea • Unpleasant sensation often leading to the urge to vomit • Pruritus ani • A common chronic condition of itching of the skin around the anus

30. Common Signs and Symptoms • Steatorrhea • Greater than normal amounts of fat in the feces • Characterized by frothy, foul-smelling fecal matter that floats • Vomit • To expel the contents of the stomach through the esophagus and out of the mouth

31. PATHOLOGICAL CONDITIONS Digestive System

32. Achalasia • Pronounced • (ak-al-LAY-zee-ah) • Defined • Decreased mobility of the lower two-thirds of the esophagus along with constriction of the lower esophageal sphincter

33. Anal Fistula • Pronounced • (AY-nal FISS-too-lah) • Defined • Abnormal passageway in the skin surface near the anus usually connecting with the rectum • May occur as the result of a draining abscess

34. Aphthous Stomatitis • Pronounced • (AFF-thus stoh-mah-TYE-tis) • Defined • Small inflammatory noninfectious ulcerated lesions occurring in the lips, tongue, and inside the cheeks of the mouth • Also called canker sores

35. Appendicitis • Pronounced • (ap-pen-dih-SIGH-tis) • Defined • Inflammation of the vermiform appendix • Usually an acute condition that can lead to rupture (perforation) with resultant inflammation of the peritoneum (peritonitis)

36. Celiac Disease • Pronounced • (SEE-lee-ak disease) • Defined • Nutrient malabsorption due to damaged small bowel mucosa

37. Cirrhosis • Pronounced • (sih-ROH-sis) • Defined • Disease of the liver that is chronic and degenerative causing injury to the hepatocytes (functional cells of the liver) • Fat infiltrates lobules of the liver, causing tissue covering the lobes to become fibrous • Functions of liver eventually deteriorate

38. Colorectal Cancer • Pronounced • (koh-loh-REK-tal CAN-sir) • Defined • Presence of a malignant neoplasm in the large intestine

39. Constipation • Pronounced • (kon-stih-PAY-shun) • Defined • A state in which the individual’s pattern of bowel elimination is characterized by a decrease in the frequency of bowel movements and the passage of hard, dry stools • Individual experiences difficult defecation

40. Crohn’s Disease • Pronounced • (KROHNZ dih-ZEEZ) • Defined • Digestive tract inflammation of a chronic nature causing fever, cramping, diarrhea, weight loss, and anorexia

41. Dental Caries • Pronounced • (DEN-tal KAIR-eez) • Defined • Tooth decay caused by acid-forming microorganisms

42. Dysentery • Pronounced • (DISS-en-ter-ee) • Defined • A term used to describe painful intestinal inflammation typically caused by ingesting water or food containing bacteria, protozoa, parasites, or chemical irritants • Person has frequent stools that often contain blood

43. Diverticular Disease • Pronounced • (dye-ver-TIK-yoo-lar dih-ZEEZ) • Defined • Expression used to characterize both diverticulosis and diverticulitis • Diverticulosis = non-inflamed outpouchings or herniations of the muscular layer of the intestines, typically the sigmoid colon • Diverticulitis = inflammation of these outpouchings

44. Esophageal Varices • Pronounced • (eh-soff-ah-JEE-al VAIR-ih-seez) • Defined • Swollen, twisted (tortuous) veins located in the distal end of the esophagus

45. Gallstones (Cholelithiasis) • Pronounced • (koh-lee-lih-THIGH-ah-sis) • Defined • Pigmented or hardened cholesterol stones formed as a result of bile crystallization

46. Hemorrhoids • Pronounced • (HEM-oh-roydz) • Defined • Hemorrhoid is an unnaturally distended or swollen vein (varicosity) in distal rectum or anus

47. Hepatitis • Pronounced • (hep-ah-TYE-tis) • Defined • Acute or chronic inflammation of the liver due to a viral or bacterial infection, drugs, alcohol, toxins, or parasites

48. Hernia • Pronounced • (HER-nee-ah) • Defined • Irregular protrusion of tissue, organ, or a portion of an organ through an abnormal break in the surrounding cavity’s muscular wall

49. Herpetic Stomatitis • Pronounced • (her-PEH-tic stoh-mah-TYE-tis) • Defined • Inflammatory infectious lesions in or on the oral cavity occurring as a primary or a secondary viral infection caused by herpes simplex

50. Hirschsprung’s Disease (Congenital Megacolon) • Pronounced • (HIRSH-sprungz dih-ZEEZ) • (kon-JEN-ih-tal meg-ah-KOH-lon) • Defined • Absence at birth of the autonomic ganglia in a segment of the intestinal smooth muscle wall that normally stimulates peristalsis