1. CHAPTER 15 DIGESTIVE SYSTEM
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2. 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
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3. Digestive Organs- Mouth
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Salivary Glands
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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
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Digestive Organs
Esophagus- (eso=inward, phag/o=to swallow); it is a 9”-10” tube that extends from pharynx to stomach.
**Rythmic 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
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7. Stomach Fig. 5-7. Back MENU Forward
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8. 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
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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 sm intestine to digest and absorb into the blood stream.
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10. Gastrointestinal Tract
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Small Intestines
Small Intestine (3 parts)- millions of tiny villi line walls of sm 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 lg intestines)
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12. Accessory Organs of the Digestive System
• Accessory organs that aid in the process of food breakdown
– Pancreas
– Liver
– Gallbladder
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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.
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Accessory Organs
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Large Intestines
Large Intestines (6 parts): goes from the end of ileum to anus; receives waste products of digestion (not able to be absorped into bloodstream) and then stores them until they are released as feces/defecation.
Cecum- pouch on rt 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)
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Pathway for Digestion
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17. Assessment Techniques
Radiography
Endoscopy
Gastric analysis
Fecal analysis
Palpation
Auscultation
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18. 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
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19. 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
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20. 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
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21. 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
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22. 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
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23. 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
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24. 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
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