The Digestive System Objectives 31 1 Spell define

The Digestive System Objectives 31 -1 Spell, define, and correctly use the Key Terms in this chapter. 31 -2 List the functions of the digestive system. 31 -3 Trace the pathway of food through the alimentary canal. 31 -4 Describe the structure and functions of the mouth, teeth, tongue, and salivary glands. 31 -5 Describe the structure and function of the pharynx. 1

The Digestive System Objectives (cont. ) 31 -6 Describe the swallowing process. 31 -7 Describe the structure of the esophagus and tell how it propels food into the stomach. 31 -8 Describe the structure and functions of the stomach. 31 -9 List the substances secreted by the stomach and give their functions. 31 -10 Describe the structure and functions of the small intestine. 2

The Digestive System Objectives (cont. ) 31 -11 31 -12 31 -13 List the substances secreted by the small intestine and describe the importance of each. Explain the structures and functions of the liver, gallbladder, and pancreas. List the substances released by the liver, gallbladder, and pancreas into the small intestine and give the function of each secretion. 3

The Digestive System Objectives (cont. ) 31 -14 Describe the structure and functions of the large intestine. 31 -15 Tell what types of nutrients are absorbed by the digestive system and where they are absorbed. 31 -16 Describe the signs, symptoms, causes, and treatments of various disorders and diseases of the digestive system. 4

Introduction ❑ Digestion ❑ ❑ ❑ The mechanical and chemical breakdown of foods into forms that your body cells can absorb The organs of the digestive system carry out digestion. Two categories ❑ ❑ Those of the alimentary canal The accessory organs 5

Alimentary Canal ❑ Length of the entire canal is about 9 meters (29 feet) ❑ ❑ ❑ Mucosa - absorbs ❑ Serosa - secretes nutrients serous fluid to keep the outside of the Submucosa - carry away canal moist and absorbed nutrients prevent it from Muscular layer - move sticking to other materials through the organs. canal 6

Mouth, Teeth, Tongue, and Salivary Glands ❑ ❑ ❑ Mouth takes in food and reduces its size through chewing Salivary glands - saliva (spit) contains an enzyme that will break down carbohydrates Teeth act to decrease the size of food particles and different types of teeth are adapted to handle food in different ways 7

Apply Your Knowledge What is the purpose of the serosa? 8

Apply Your Knowledge -Answer What is the purpose of the serosa? Serosa - secretes serous fluid to keep the outside of the alimentary canal moist and prevent it from sticking to other organs. 9

Pharynx The throat - long, muscular structure that extends from the area behind the nose to the esophagus ❑ Nasopharynx ❑ Oropharynx ❑ Laryngopharynx ❑ Acts to connect the nasal cavity with the oral cavity for breathing through the nose ❑Acts to push food into the esophagus 10

Swallowing Process An involuntary automatic response (reflex) 1. Soft palate raises causing the uvula to cover the opening between the nasal cavity and oral cavity 2. Epiglottis covers the opening of the larynx 11

Swallowing Process (cont. ) 3. 4. 5. Muscles in the pharynx contract, forcing food toward the esophagus Esophagus opens Food is pushed into the esophagus by the muscles of the pharynx 12

Esophagus ❑ ❑ Esophagus is a muscular tube about 25 cm long that connects the pharynx to the stomach Esophageal sphincter controls the movement of food into the stomach ❑ Opens and closes to allow or prevent movement of substances out of a tube 13

Stomach ❑ Below the diaphragm in the upper left region of the abdominal cavity ❑ It functions to receive food from the esophagus ❑ Mix food with gastric juice (secretions of the stomach lining) ❑ Start protein digestion ❑ Move food into the small intestine Click for Larger View 14

Stomach (cont. ) 15

Stomach Secretions When a person smells, tastes, or sees appetizing food, the parasympathetic nervous system stimulates the gastric glands to secrete their products. Gastrin, made by the stomach, also stimulates gastric glands to become active. Chief cells - secrete pepsinogen, which becomes pepsin in the presence of acid. Pepsin digests proteins. 16

Stomach Secretions (cont. ) Parietal cells – ❑ secrete hydrochloric acid, that convert pepsinogen to pepsin. ❑ secrete intrinsic factor, which is necessary for vitamin B 12 absorption. 17

Small Intestine ❑ Small intestine is a tubular organ that extends from the stomach to the large intestine ❑ Carries out most digestion in the body and is responsible for absorbing most of the nutrients into the bloodstream 18

Small Intestine - Secretions ❑ ❑ ❑ Peptidases - enzymes that digest proteins. Intestinal lipase - an enzyme that digests fats Sucrase, maltase, and lactase - Digest sugars. ❑ If a person cannot produce lactase, he will not be able to digest lactose, which is the sugar in dairy products - lactose intolerance 19

Apply Your Knowledge Your patients states that she is lactose intolerant. What does that mean? 20

Apply Your Knowledge -Answer Your patient states that she is lactose intolerant. What does that mean? She cannot produce lactase and cannot digest lactose, which is the sugar in dairy products; thus, she is lactose intolerant. 21

Pancreas ❑Pancreas is located behind the stomach. ❑Pancreatic acinar cells produce pancreatic juice. ❑Pancreatic juice contains the following enzymes: ❑ ❑ ❑ Pancreatic amylase - digests carbohydrates Pancreatic lipase - digests lipids Nucleases - digests nucleic acids ❑ Trypsin, chymotrypsin, and carboxypeptidase - digest proteins 22

Liver ❑ ❑ Reddish-brown in color Large organ that fills most of the upper right abdominal quadrant Has a large right lobe and a small left lobe - separated into smaller divisions called hepatic lobules. Hepatic lobules contain macrophages that destroy bacteria and viruses in the blood Stores vitamins and iron 23

Liver (cont. ) ❑ Each hepatic lobule contains many cells called hepatocytes ❑ ❑ Process the nutrients in blood and make bile, which is used in the digestion of fats Bile leaves the liver through the hepatic duct 24

Gallbladder Small sac-like structure located beneath the liver ❑ Only function is to store bile ❑ Cholecystokinin causes the gallbladder to release bile ❑ Gallbladder 25

Large Intestine ❑ Large intestine extends from the ileum of the small intestine to where it opens to the outside world as the anus 26

Large Intestine (cont. ) ❑ ❑ Lining of the large intestine - secretes mucus to aid in the movement of substances Large intestine absorbs water and a few electrolytes from chyme; the left over forms feces 27

The Absorption of Nutrients ❑ Nutrients are defined as necessary food substances and are absorbed in the small intestine ❑ ❑ ❑ Carbohydrate Proteins Lipids Vitamins Minerals Water 28

Apply Your Knowledge Why can a person live without their gallbladder? 29

Apply Your Knowledge -Answer Why can a person live without their gallbladder? It’s only purpose is to store bile. As long as a person is still making bile in the liver, they can still digest fats. 30

Diseases and Disorders of the Digestive System ❑ ❑ Appendicitis - an inflammation of the appendix Causes ❑ ❑ ❑ Blockage of appendix with feces Blockage of appendix with tumor Treatments ❑ ❑ Surgery to remove appendix Antibiotics to prevent infection Signs and symptoms – lack of appetite, pain in and around the navel area or in the abdomen, nausea, slight fever, pain in the right leg, and increased white blood cell content 31

Diseases and Disorders of the Digestive System ❑ ❑ ❑ Cirrhosis - a long lasting liver disease in which normal liver tissue is replaced with nonfunctional scar tissue Causes - Excessive alcohol consumption ❑ Hepatitis C infection ❑ Hepatitis B infection Treatment - Liver transplant ❑ Lifestyle changes to stop medications or use of alcohol 32

Cirrhosis

Diseases and Disorders of the Digestive System (cont. ) ❑ ❑ ❑ Colitis - defined as inflammation of the large intestine Causes - caused by viral or bacterial infection or the use of antibiotics. Ulcers in the large intestine, Crohn’s disease, various other diseases, and stress may contribute. Treatments ❑ ❑ Treating underlying causes Changing antibiotics Fluids Repair of ulcers 34

Colitis

Diseases and Disorders of the Digestive System (cont. ) ❑ ❑ ❑ Colorectal cancer usually comes from the lining of the rectum or colon. Causes - mostly unknown. Polyps in colon or rectum can become cancerous. Signs ❑ Changes in bowel movement ❑ Blood in feces ❑ Anemia ❑ Abdominal pain ❑ Weight loss ❑ Narrow feces 36

Colorectal Cancer

Diseases and Disorders of the Digestive System (cont. ) ❑ ❑ ❑ Crohn’s disease - a common type of inflammatory bowel disease and is an autoimmune disorder that typically affects the end of the small intestine Causes - this is an autoimmune disorder. Treatment ❑ ❑ Medications to reduce inflammation Antibiotics Surgery to remove affected part of intestine Changes in diet 38

Chrohn’s Disease

Diseases and Disorders of the Digestive System (cont. ) ❑ ❑ ❑ Diverticulitis - inflammation of diverticuli in the intestine. Diverticuli are abnormal dilations in the intestinal wall Causes – mostly unknown. Lack of fiber in diet and bacterial infection of the diverticuli. Signs ❑ Abdominal pain ❑ Constipation ❑ Diarrhea & nausea ❑ Fever ❑ Blood in feces ❑ High white blood cell count 40

Diverticulitis

Diseases and Disorders of the Digestive System (cont. ) ❑ ❑ ❑ Gastritis - an inflammation of the stomach lining Causes - bacteria or viruses, some medications, alcohol, spicy foods, excessive eating poisons, and stress. Treatment ❑ Cook food properly to kill bacteria/viruses ❑ Avoid foods/medications that irritate stomach linings ❑ Begin acid reducing medications 42

Gastritis

Diseases and Disorders of the Digestive System (cont. ) ❑ ❑ ❑ Heartburn - called gastroesophageal reflux disease (GERD) - occurs when stomach acids are pushed into the esophagus Causes – alcohol, some foods, defective esophageal sphincter, pregnancy, obesity, hiatal hernia, and repeated vomiting. Treatment ❑ Reducing weight ❑ Diet changes ❑ Reduce alcohol consumption ❑ Medications ❑ Not lying down after meal 44

Heartburn

Diseases and Disorders of the Digestive System (cont. ) ❑ ❑ ❑ Hemorrhoids - varicose veins of the rectum or anus Causes – constipation, excessive straining during bowel movements, liver disease, pregnancy, and obesity. Treatment ❑ ❑ Eating high fiber Stool softeners Medications Surgery 46

Hemorrhoids

Diseases and Disorders of the Digestive System (cont. ) ❑ ❑ ❑ Hepatitis - inflammation of the liver. Causes - bacteria, viruses, parasites, immune disorders, the use of alcohol and drugs, and overdose of acetaminophen. Treatment ❑ ❑ Avoid drugs and alcohol Prescribed medications 48

Hepatitis

Diseases and Disorders of the Digestive System (cont. ) ❑ ❑ ❑ Hiatal hernia - occurs when a portion of the stomach protrudes into the chest through an opening in the diaphragm. Inguinal hernias - occurs when a portion of the large intestine protrudes into the inguinal canal. Oral cancer - usually involves the lips or tongue, but can occur anywhere in the mouth. Pancreatic cancer – 4 th leading cause of death in the U. S. Stomach cancer - most common in the upper part of the stomach. Stomach ulcers - occur in the lining of the stomach 50

Apply Your Knowledge Your patient has been diagnosed with Crohn’s disease. What is the usual treatment for this disease? 51

Apply Your Knowledge -Answer Your patient has been diagnosed with Crohn’s disease. What is the usual treatment for this disease? Treatment for Crohn’s disease includes medications to reduce inflammation, antibiotics, surgery to remove affected part of intestine and/or changes in diet 52

Summary Medical Assistant Knowledge of the digestive system will assist you in providing care for the patient with diseases and disorders of the digestive system. 53

End of Chapter 54