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Chapter 19: The Digestive System
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Overview
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Key Terms absorption esophagus peristalsis bile gallbladder peritoneum
chyle hydrolysis saliva chyme ingestion sphincter defecation intestine stomach deglutition lacteal ulcer digestion liver villi duodenum mastication emulsify pancreas
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General Structure and Function of the Digestive System
Learning Outcomes 1. Name the three main functions of the digestive system. 2. Describe the four layers of the digestive tract wall. 3. Name and locate the two main layers and the subdivisions of the peritoneum.
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General Structure and Function of the Digestive System
General Functions Digestion Absorption Elimination Divisions Digestive tract Accessory organs
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General Structure and Function of the Digestive System
The Wall of the Digestive Tract Mucosa Submucosa Muscularis Serosa
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Figure 19-1 Wall of the digestive tract.
What type of tissue is between the submucosa and the serous membrane in the digestive tract wall?
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General Structure and Function of the Digestive System
Peritoneum Lines abdominopelvic cavity; covers abdominal organs Layers of the peritoneum Parietal Visceral Subdivisions Mesentery Mesocolon Greater omentum Lesser omentum
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General Structure and Function of the Digestive System
Peritoneum Peritoneal cavity: Space between two layers of the membrane Greater peritoneal cavity: Main portion, located in abdominal cavity, extends into pelvic cavity Lesser peritoneal cavity: Extends to liver and back attachment of diaphragm
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Figure 19-2 The abdominopelvic cavity and peritoneum.
Which part of the peritoneum is around the small intestine? 10
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General Structure and Function of the Digestive System
✓ General Structure and Function of the Digestive System Checkpoints 19-1 Why does food have to be digested before cells can use it? 19-2 What are the typical four layers of the digestive tract wall? 19-3 What is the name of the large serous membrane that lines the abdominopelvic cavity and covers the organs it contains? 11
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General Structure and Function of the Digestive System
? General Structure and Function of the Digestive System Pop Quiz 19.1 Which of the following is the correct order from the outermost to innermost layer? A) Submucosa, serous membrane, smooth muscle, mucous membrane B) Smooth muscle, serous membrane, mucous membrane, submucosa C) Serous membrane, smooth muscle, submucosa, mucosa D) Mucous membrane, submucosa, smooth muscle, serous membrane
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General Structure and Function of the Digestive System
? General Structure and Function of the Digestive System Pop Quiz Answer 19.1 Which of the following is the correct order from the outermost to innermost layer? A) Submucosa, serous membrane, smooth muscle, mucous membrane B) Smooth muscle, serous membrane, mucous membrane, submucosa C) Serous membrane, smooth muscle, submucosa, mucosa D) Mucous membrane, submucosa, smooth muscle, serous membrane
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Organs of the Digestive Tract
Learning Outcomes 4. Name and locate the different types of teeth. 5. Name and describe the functions of the digestive tract organs.
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Organs of the Digestive Tract
Mouth Pharynx Esophagus Stomach Small intestine Large intestine
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Figure 19-3 The digestive system.
Which accessory organs of digestion secrete into the mouth? 16
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Organs of the Digestive Tract
The Mouth Also called oral cavity, processes food by Ingestion Mastication Mixing with saliva Deglutition
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Figure 19-4 The mouth. 18
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Organs of the Digestive Tract
The Teeth Types of teeth Incisors Cuspids Premolars Molars Sets of teeth Deciduous Permanent
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Figure 19-5 A molar tooth. What is the common name for the gingiva? 20
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Organs of the Digestive Tract
The Pharynx Also called the throat Divisions Oropharynx Nasopharynx Laryngopharynx
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Organs of the Digestive Tract
The Esophagus Muscular tube No digestion occurs here Passes through esophageal hiatus of diaphragm to join stomach
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Organs of the Digestive Tract
The Stomach Structure Fundus Body Pylorus Sphincters Esophageal Pyloric Rugae
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Figure 19-6 Longitudinal section of the stomach.
Which additional muscle layer is in the wall of the stomach that is not found in the rest of the digestive tract? 25
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Organs of the Digestive Tract
The Stomach Functions Storage of food Secretion of gastric juice Hydrochloric acid prepares proteins for digestion Pepsin digests proteins Delivery of chyme to small intestine via peristalsis
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Organs of the Digestive Tract
The Small Intestine Divisions Duodenum Jejunum Ileum Functions Enzymatic digestion of proteins and carbohydrates Absorption of nutrients Delivery of chyme to large intestine (segmentation)
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Figure 19-7 The intestines.
Which portions of the small and large intestines join at the ileocecal valve? 28
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Organs of the Digestive Tract
The Small Intestine Role of villi in small intestine Structure Microvilli Function Increase surface area for digestion and absorption
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Organs of the Digestive Tract
Divisions of the Large Intestine Cecum Ileocecal valve Appendix Ascending colon Transverse colon Descending colon Sigmoid colon Rectum Anus
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Organs of the Digestive Tract
Functions of the Large Intestine Secrete mucus Reabsorb some water Form feces (stool) Defecation
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Organs of the Digestive Tract
✓ Organs of the Digestive Tract Checkpoints 19-4 How many baby teeth are there and what is the scientific name for the baby teeth? 19-5 What type of food is digested in the stomach? 19-6 What are the three divisions of the small intestine? 19-7 How does the small intestine function in the digestive process? 19-8 What are the divisions of the large intestine? 19-9 What are the functions of the large intestine? 32
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Organs of the Digestive Tract
? Organs of the Digestive Tract Pop Quiz 19.2 Which organ receives food flowing through the pyloric sphincter? A) Stomach B) Jejunum C) Duodenum D) Esophagus
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Organs of the Digestive Tract
? Organs of the Digestive Tract Pop Quiz Answer 19.2 Which organ receives food flowing through the pyloric sphincter? A) Stomach B) Jejunum C) Duodenum D) Esophagus
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Accessory Organs of Digestion
Learning Outcomes 6. Name and describe the functions of the accessory organs of digestion. 7. Describe how bile travels into the digestive tract and functions in digestion.
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Accessory Organs of Digestion
Release secretions through ducts into digestive tract Salivary glands open to mouth All other organs open to duodenum Liver Gallbladder Pancreas
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Accessory Organs of Digestion
Salivary Glands Types Parotid glands Submandibular glands Sublingual glands Functions Secrete saliva Moistens food Facilitates mastication and deglutition Helps keep teeth and mouth clean
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Figure 19-8 Salivary glands.
Which salivary glands are directly below the tongue? 38
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Accessory Organs of Digestion
Structure of the Liver Right, left lobes Portal vein Hepatic artery
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Accessory Organs of Digestion
Functions of the Liver Manufactures bile Stores glycogen, convert to glucose Modifies fats Stores vitamins, iron Forms blood plasma proteins Destroys old red blood cells Synthesizes urea Detoxifies harmful substances
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Accessory Organs of Digestion
The Gallbladder Stores bile Bile manufactured in liver Flows from liver to gallbladder via cystic duct Flows from gallbladder to duodenum via cystic duct and common bile duct when needed
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Accessory Organs of Digestion
✓ Accessory Organs of Digestion Checkpoints What are the names and locations of the salivary glands? Which accessory organ secretes bile and what is the function of bile in digestion? What is the role of the gallbladder? What accessory organ secretes sodium bicarbonate and what is the function of this substance in digestion? 42
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Figure Hydrolysis. 43
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Digestion, Step-by-Step
Mouth Chews food, mixes with saliva Some starches changed to sugars via salivary amylase Stomach Secretes HCl, enzymes Secretes mucus Forms chyme Begins digestion of proteins (via HCl and pepsin)
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Digestion, Step-by-Step
Small Intestine Mixes chyme with bile Receives pancreatic juice enzymes Produces enzymes Digests all nutrients via pancreatic and intestinal enzymes Emulsifies fats via bile
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Absorption of Water-Soluble Nutrients
Villi in mucosa of small intestine Arteriole and venule bridged with capillaries Capillaries absorb Simple sugars Small proteins Amino acids Simple fatty acids Water Portal system transports nutrients to liver
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Absorption of Fats Lacteals absorb fat
Fat/lymph mixture (chyle) drains from small intestine Chyle merges with lymphatic circulation, enters blood in veins near heart Liver further processes absorbed fats
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Absorption of Vitamins and Minerals
When vitamins and minerals are Dissolved in water Absorbed directly into blood Incorporated in fats Absorbed with fats Produced by bacterial action Absorbed in large intestine
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Enzymes and the Digestive Process
✓ Enzymes and the Digestive Process Checkpoints Which organ produces the most complete digestive secretions? What is absorption? 50
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Enzymes and the Digestive Process
? Enzymes and the Digestive Process Pop Quiz 19.4 Which enzymes digests carbohydrates? A) Amylase B) Pepsin C) Lipase D) Trypsin
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Enzymes and the Digestive Process
? Enzymes and the Digestive Process Pop Quiz Answer 19.4 Which enzymes digests carbohydrates? A) Amylase B) Pepsin C) Lipase D) Trypsin
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Control of Digestion and Eating
Learning Outcomes 11. Explain the use of feedback in regulating digestion and give several examples. 12. List several hormones involved in regulating digestion.
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Control of Digestion and Eating
Nervous Control of Digestion Parasympathetic stimulation increases activity Sympathetic stimulation decreases activity Hormonal Control of Digestion Digestive organs produce hormones Gastrin Gastric-inhibitory peptide (GIP) Secretin Cholecystokinin
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Control of Digestion and Eating
Hunger Hypothalamic centers regulate Blood nutrient levels stimulate Satisfied by adequate meal Appetite No relationship to need for food May not be satisfied by adequate meal Leptin; hormone produced in adipose tissue; involved in weight regulation
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Control of Digestion and Eating
✓ Control of Digestion and Eating Checkpoints What are the two types of control over the digestive process? What is the difference between hunger and appetite? 56
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Control of Digestion and Eating
? Control of Digestion and Eating Pop Quiz 19.5 Which portion of the autonomic nervous system inhibits digestion? A) Somatic B) Parasympathetic C) Sympathetic D) Visceral
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Control of Digestion and Eating
? Control of Digestion and Eating Pop Quiz Answer 19.5 Which portion of the autonomic nervous system inhibits digestion? A) Somatic B) Parasympathetic C) Sympathetic D) Visceral
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Disorders of the Digestive System
Learning Outcome 13. Describe common disorders of the digestive tract and the accessory organs.
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Disorders of the Digestive System
Eating Disorders Anorexia Chronic loss of appetite Possible emotional, social factors Anorexia nervosa Psychological disorder Bulimia (binge-purge syndrome)
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Disorders of the Digestive System
Peritonitis Infection of the peritoneum following infection of an organ covered by peritoneum Localized Generalized
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Disorders of the Digestive System
Diseases of the Mouth and Teeth Dental caries Gingivitis Periodontitis Vincent disease Leukoplakia
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Disorders of the Digestive System
Disorders of the Esophagus Acid reflux Varicose veins of the esophagus Hiatal hernia Heartburn Chronic reflux or gastroesophageal reflux disease (GERD)
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Disorders of the Digestive System
Disorders of the Stomach Nausea Vomiting (emesis) Gastritis Flatulence Stomach cancer Peptic ulcer Pyloric stenosis
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Figure 19-11 Disorders involving the esophagus and stomach.
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Disorders of the Digestive System
Intestinal Disorders Inflammatory disorders Appendicitis Crohn disease Ulcerative colitis Celiac disease Inflammatory bowel syndrome Diverticulitis
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Disorders of the Digestive System
Intestinal Disorders (continued) Diarrhea Constipation Obstruction Intussusceptions Volvulus Ileus Hemorrhoids Colon and rectal cancer
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Figure 19-12 Intestinal obstructions.
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Disorders of the Digestive System
Liver Disorders Cirrhosis Active liver cells replaced by scar tissue Alcoholic (portal) type is most common Jaundice Hepatitis Cancer
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Disorders of the Digestive System
Gallbladder Disorders Cholelithiasis Cholecystitis Pancreatic Disorders Pancreatitis Cancer
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Figure Gallstones. 74
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Disorders of the Digestive System
✓ Disorders of the Digestive System Checkpoints What are some common diseases of the mouth and teeth? Which two diseases fall into the category of inflammatory bowel disease? What is hepatitis? 76
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Aging and the Digestive System
Decreased digestive organ activity Decrease in saliva Tooth loss Poor nutrient absorption Slowing of peristalsis Decreased tissue replacement Increased risk of cancer
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Case Study Learning Outcome
14. Using the case study, describe the colonoscopy procedure and its role in diagnosing certain colon disorders. 78
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Figure Colonoscopy. 79
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Word Anatomy Learning Outcome
15. Show how word parts are used to build words related to digestion. 80
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Word Anatomy Word Part Meaning Example ab- away from
In absorption, digested materials are taken from the digestive tract into the circulation. enter/o intestine The mesentery is the portion of the peritoneum around the intestine. mes/o- middle The mesocolon, like the mesentery, comes from the middle layer of cells in the embryo, the mesoderm. amyl/o starch The starch-digesting enzyme in saliva is salivary amylase. cyst/o bladder, sac The cystic duct carries bile into and out of the gallbladder. chole bile, gall Cholecystokinin is a hormone that activates the gallbladder (cholecyst/o). lith- stone A fecalith is a hardened piece of fecal material.
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