Copyright 2003 by Mosby, Inc. All rights reserved. CHAPTER 15 DIGESTIVE SYSTEM

Copyright 2003 by Mosby, Inc. All rights reserved. Structure and Function The structure of the digestive system consists of the organs that comprise the alimentary canal, or digestive tract The functions of the digestive system are: – To break down food to a form that can be used by body cells – The digestive process, which includes transporting food and wastes, physical and chemical breakdown, absorption of digested food, and final elimination of wastes

Copyright 2003 by Mosby, Inc. All rights reserved. Organs of the Digestive Process Mouth and teeth Pharynx (throat) Esophagus Stomach Small intestine Large intestine Peritoneum

Digestive Organs- Mouth Copyright 2003 by Mosby, Inc. All rights reserved.

Digestive Organs- Teeth Copyright 2003 by Mosby, Inc. All rights reserved.

Tooth Copyright 2003 by Mosby, Inc. All rights reserved.

Salivary Glands Copyright 2003 by Mosby, Inc. All rights reserved.

Digestive Organs Pharynx/throat- muscular tube lined with a mucous membrane and serves as a common passageway for air traveling to nasal cavity, trachea, and food going to the esophogus Epiglottis- flap in back of throat that covers trachea so food can’t enter trachea Copyright 2003 by Mosby, Inc. All rights reserved.

Small Intestines Small Intestine (3 parts)- millions of tiny villi line walls of small intestines; these tiny villi absorb the digested nutrients into the bloodstream and lymph vessels – Duodenum- receives food from the stomach as well as bile from the liver, gall bladder, and pancreas –Jejunum –Ileum (leads to the large intestines) Copyright 2003 by Mosby, Inc. All rights reserved.

Large Intestines Large Intestines (6 parts): goes from the end of ileum to anus; receives waste products of digestion (not able to be absorbed into bloodstream) and then stores them until they are released as feces/defecation. Cecum- pouch on right side and connects to ileum (appendix hangs from the cecum) Asending colon- going from cecum to liver; it then turns left and becomes: Transverse colon- then passes horizontally towards spleen and becomes: Descending colon Sigmoid colon- “s” shaped; lies at distal end and leads to the Rectum- (then goes to the anus) Copyright 2003 by Mosby, Inc. All rights reserved.

Gastrointestinal Tract Copyright 2003 by Mosby, Inc. All rights reserved.

Digestive Organs Esophagus- (eso=inward, phag/o=to swallow); it is a 9”- 10” tube that extends from pharynx to stomach. **Rhythmic contractions of muscles propels food towards the stomach –Peristalsis- peri=surrounding, -stalsis=contraction: is the involuntary contraction of the esophagus Ileus- failure of peristalsis Achalasia= failure of the lower esophagus spincter to relax so food cannot pass Dysphagia- (dys=bad; phagia=eat or swallow); difficulty in swallowing/eating Copyright 2003 by Mosby, Inc. All rights reserved.

Stomach and Sphincters Bolus- semisolid food going through esophagus into upper portion of stomach called the fundus. Food then goes to the body of the stomach or the middle section, and then the lower portion called the antrum. Sphincter- muscle rings controlling the openings into and out of the stomach: Pyloric sphincter- ring at distal end of stomach that allows food to leave stomach. Cardiac sphincter- ring at superior portion of stomach- relaxes and contracts food from esophagus into the stomach Copyright 2003 by Mosby, Inc. All rights reserved.

Copyright © 2001 by W. B. Saunders Company. All rights reserved. Stomach Fi g Forward Back MENU

Stomach and Digestion *Mucous lines the stomach in folds called rugae which contains digestive glands that produce pepsin enzymes and hydrochloric acid. This begins the process of digestion. Food digests in about 1-4 hours where it is chemically and mechanically prepared for the small intestine to digest and absorb into the blood stream. Copyright 2003 by Mosby, Inc. All rights reserved.

Accessory Organs of the Digestive System Accessory organs that aid in the process of food breakdown – Pancreas – Liver – Gallbladder

Accessory Organs Liver- manufactures bile which contains cholesterol, acids, and pigments such as bilirubin; regulates glucose in blood and stores it as glycogen. (Cirrohosis is liver disease resulting from alcoholism and malnutrition) Gallbladder- contracts to force out bile to the cystic duct into the common bile duct (which carries bile into the duodenum) Pancreas- secretes enzymes and insulin that travel through the pancreatic duct to duodenum. It is here that bile breaks apart large fat globules which is called emulsification. Without bile, most fat would be undigested. The pancreas produces enzymes to digest starch called amylase. Lipase digests fats; pepcin digests proteins. Copyright 2003 by Mosby, Inc. All rights reserved.

Accessory Organs Copyright 2003 by Mosby, Inc. All rights reserved.

Pathway for Digestion Copyright 2003 by Mosby, Inc. All rights reserved.

Assessment Techniques Radiography Endoscopy Gastric analysis Fecal analysis Palpation Auscultation

Copyright 2003 by Mosby, Inc. All rights reserved. Disorders of the Digestive System Alactasia –Also called “lactose intolerance.” Not enough of the enzyme lactase is produced. The unabsorbed lactose ferments in the intestines leading to gas, cramps, and diarrhea. Appendicitis –Inflammation of the appendix Cholecystitis –Inflammation of the gallbladder

Copyright 2003 by Mosby, Inc. All rights reserved. Disorders of the Digestive System (continued) Cirrhosis –A chronic degenerative condition of the liver accompanied by the formation of scar tissue Colon cancer –An abnormal growth in the large intestine Constipation –The inability to defecate Crohn’s disease –Inflammation and ulceration, usually affecting the ileum and colon, or both

A) Cirrohsis B) Cholesterol Gallstones Copyright 2003 by Mosby, Inc. All rights reserved.

Crohn’s Copyright 2003 by Mosby, Inc. All rights reserved.

Disorders of the Digestive System Diarrhea –The passage of frequent and watery stools Diverticulitis –The weakening of the colon wall, leading to formation of a pouch causing infection or abscesses if fecal material trapped Food poisoning –Illnesses transmitted by food

Copyright 2003 by Mosby, Inc. All rights reserved. Disorders of the Digestive System (continued) Gastritis –Inflammation of the stomach lining Gastroesophageal reflux disease –Frequent heartburn or chest pain, bitter taste in the mouth, difficulty swallowing, frequent hoarseness or coughing Halitosis –Or bad breath, is caused by anaerobic bacteria

Copyright 2003 by Mosby, Inc. All rights reserved. Disorders of the Digestive System (continued) Heartburn –A painful burning sensation in the esophagus caused by the backflow of acidic chyme from the stomach Hemorrhoid –A painful dilated vein in the lower rectum or anus Hepatitis –A viral infection of the liver

Copyright 2003 by Mosby, Inc. All rights reserved. Disorders of the Digestive System (continued) Mumps –A highly contagious viral infection of the parotid glands Pancreatitis –A mild acute or chronic condition resulting from gallbladder stone blockage, disease, injury, or alcoholism Peritonitis –An inflammation of the abdominal cavity caused by bacteria

Copyright 2003 by Mosby, Inc. All rights reserved.

Disorders of the Digestive System (continued) Phenylketonuria (PKU) –Inherited disease that can lead to mental retardation if untreated Pyloric stenosis –A birth defect in which a constricted pyloric sphincter does not allow food to pass easily into the small intestine

Copyright 2003 by Mosby, Inc. All rights reserved. Disorders of the Digestive System (continued) Tay-Sachs –A recessive genetic disorder in which fat cells accumulate in the body and cause damage to normal cells Ulcer –An open sore on the lining of the digestive tract

Copyright 2003 by Mosby, Inc. All rights reserved. Issues and Innovations Food-borne illness – Salmonella bacteria – Escherichia coli – Sulfite-sensitive people Eating disorders – Bulimia and anorexia nervosa Designer foods –Biotechnologically engineered food