Chapter 23
Digestive System
I. INTRODUCTION
A. Digestive organs
1. Alimentary canal (GI tract)
2. Accessory digestive organs
B. Digestive processes
1. Ingestion
2. Propulsion
3. Mechanical digestion
4. Chemical digestion
5. Absorption
6. Defecation
C. Structural plan of digestive organs
1. Visceral and parietal peritoneum
2. Peritoneal cavity
3. Mesenteries
4. Retroperitoneal organs
5. Blood supply
D. Histology of the alimentary canal
1. Mucosa
2. Submucosa
3. Muscularis externa
4. Serosa
II. FUNCTIONAL ANATOMY OF THE DIGESTIVE SYSTEM
A. Upper digestive tract
1. Mouth
a. Lips and cheeks
b. Palate
i. Hard palate
ii. Soft palate
iii. Uvula
c. Tongue
i. Types of papillae
ii. Taste buds
d. Salivary glands
i. Types of salivary glands (parotid, sublingual, and submandibular)
ii. Composition and functions of saliva
iii. Control of salivation
e. Teeth
i. Dentition and the dental formula
ii. Tooth structure
iii. Tooth and gum diseases
2. Pharynx
a. Regions
b. Histology
3. Esophagus
a. Structures
i. Esophageal hiatus
ii. Upper esophageal sphincter
iii. Cardiac or gastroesophageal sphincter
b. Histology
B. Digestive processes occurring in the mouth, pharynx, and esophagus
1. Mastication
2. Chemical digestion of starches
3. Deglutition
4. Peristalsis
C. Lower digestive tract
1. Stomach
a. Gross anatomy
i. Regions
ii. Sphincters
iii. Rugae
iv. Omentums
b. Microscopic anatomy
i. Three muscle layers
ii. Histology of the epithelial lining
iii. Gastric glands
a. Mucous neck cells and their secretions
b. Parietal cells and their secretions
c. Chief cells and their secretions
d. Enteroendocrine cells and their hormones
c. Digestive processes within the stomach
i. Regulation of gastric secretions
a. Cephalic phase
b. Gastric phase
c. Intestinal phase
ii. Gastric motility and emptying
2. Small intestines
a. Gross anatomy
i. Regions
ii. Ileocecal valve
iii. Sphincter of Oddi
b. Microscopic anatomy
i. Plicae circulares
ii. Villi
iii. Microvilli
iv. Histology of the wall
v. Intestinal juice composition and control
3. Liver and gallbladder
a. Gross anatomy of the liver
b. Microscopic anatomy of the liver
c. Gross anatomy of the gallbladder
d. Microscopic anatomy of the gallbladder
e. Composition of Bile
f. Regulation of bile release from into the small intestines
4. Pancreas
a. Microscopic anatomy
b. Composition of pancreatic juice
c. Regulation of pancreatic secretion into the small intestines
5. Large intestine
a. Gross anatomy
b. Microscopic anatomy
c. Bacterial flora
D. Digestive processes occurring in the lower digestive tract
1. Stomach
a. Chemical digestion
b. Churning and emptying
2. Small intestines (and accessory organs: liver, gallbladder and pancreas)
a. Chemical digestion
b. Segmentation and peristalsis
c. Absorption of nutrients
3. Large intestines
a. Peristalsis
b. Absorption of water, vitamins, and electrolytes
c. Defecation
III. PHYSIOLOGY OF CHEMICAL DIGESTION AND ABSORPTION
A. Chemical Digestion
1. Carbohydrate digestion
a. Salivary amylase
b. Pancreatic amylase
c. Brush border enzymes
i. Dextrinase
ii. Lactase
iii. Maltase
iv. Sucrase
2. Protein digestion
a. Pepsin (pepsinogen + HCl)
b. Pancreatic proteases
i. Trypsin
ii. Chymotrypsin
c. Brush border enzymes
i. Carboxypeptidase
ii. Aminopeptidase
iii. Dipeptidase
3. Lipid digestion
a. Lipase
b. Emulsification by bile
4. Nucleic acid digestion
a. Pancreatic nucleases
b. Brush border enzymes
B. Absorption of Nutrients
1. Carbohydrates
2. Proteins
3. Lipids
a. Micelles
b. Chylomicrons
4. Nucleic acids
5. Vitamins
6. Electrolytes
7. Water
IV. HOMEOSTATIC IMBALANCES
A. Peritonitis
B. Mumps
C. Halitosis
D. Impacted wisdom teeth
E. Heartburn
F. Hiatus hernia
G. Gastric ulcers
H. Vomiting or emesis
I. Enteritis
J. Hepatitis
K. Cirrhosis
L. Gallstones
M. Jaundice
N. Appendicitis
O. Diverticulitis
P. Diarrhea
Q. Constipation
R. Crohn’s disease
S. Inflammatory or Irritable bowel syndrome
T. Pancreatitis
U. Dysphagia
V. Bruxism
W. Ascites