1. Chapter 16 – digestive system
Major components: mouth, esophagus, stomach, intestines, liver, gallbladder, and pancreas
Major functions: mechanical and chemical breakdown of food, absorption of nutrients and elimination of wastes

2. Histology of the digestive system
Four tissue layers (tunics):
1. Mucosa – innermost tunic – mucus epithelium, lamina propria, muscularis mucosa
2. Submucosa – thick layer of loose connective tissue
3. Muscularis – inner layer of circular smooth muscle and outer layer of longitudial smooth muscle
4. Serosa or adventitia – connective tissue layer

3. Structures:
Oral cavity: mouth – bounded by lips and cheeks and contains teeth and tongue
Muscles – (lips) – orbicularis oris, buccinator, tongue, frenulum - (function – mastication)

4. teeth 32 teeth in normal adult mouth Located in mandible and maxilla
Incisors, canines, premolars, molars
See diagram page 452
Permanent vs. deciduous teeth
Structure: crown, neck, root, pulp cavity, pulp, dentin, enamel, cementum, alveoli, gingiva, periodontal ligaments, periodontal membrane

5. Palate and tonsils Palate – 2 parts: 1. Hard palate 2. Soft palate
Uvula
Tonsils – lateral, posterior walls of the oral cavity

6. Salivary glands See diagram on pg. 453 Three pairs – 1. parotid
2.Submandibular
3.sublingual

7. pharynx
Nasopharynx
Oropharynx
laryngopharynx

8. esophagus Muscular tube – extends from pharynx to stomach
About 10 inches (25 cm)
Passes through diaphragm
Upper and lower esophageal sphincters
Lined with mucous glands

9. Stomach Cardiac opening Cardiac region Fundus Body Greater curvature
Lesser curvature
Pyloric opening (sphincter)
Pyloric region

10. Stomach, continued Gastric pits Gastric glands Mucous cells
Endocrine cells
Pepsinogen/pepsin
rugae

11. Small intestine About 6 meters long (almost 20 ft)
3 sections: duodenum, jejunum, ileum
Duodenum – about 12 inches, bile duct and pancreatic duct empty into it
Duodenum has : circular folds, villi and microvilli to increase surface area

12. Small intestine, cont’d
Jejunum and ileum are similar in structure to duodenum, but diameter and numbers of villi, microvilli and circular folds decreases as you progress the length of the small intestine
Ileocecal junction, sphincter and valve are found at the junction between the ileum and the large intestine

13. liver Weighs about 3 pounds Right upper quadrant of abdomen
2 blood sources
Ducts transport bile to gall bladder

14. pancreas
Pancreatic islets
Insulin production

15. Large intestine
Cecum
Colon
Rectum
Anal canal

16. Colon
1.5 m long
Ascending
Transverse
Descending
Sigmoid
Crypts

17. peritoneum Serous membranes Visceral peritoneum Parietal peritoneum
Mesenteries
Lesser/greater omentum
Retroperitoneal organs

18. Physiology of digestive system
Oral cavity, pharynx and esophagus
Saliva – salivary amylase
Mucin
Mastication
Deglutition
Voluntary phase
Bolus

19. Swallowing, contd Pharyngeal phase Epitglottis Esophageal phase
Peristaltic waves

20. Stomach Secretions – chyme Mucus Hydrochloric acid Pepsiogen Pepsin
Intrinsic factor
gastrin

21. Regulation of stomach secretions
Cephalic phase
Gastric phase
Intestinal phase
Secretin

22. Movement in the stomach
Mixing waves
Peristaltic waves

23. Small intestine Peptidases Disaccharidases
Movement – segmental contractions, peristaltic contractions
absorption

24. liver
Digestive, excretory,stores and processes nutrients, synthesizes molecules, detoxifies
Bile/bile salts

25. pancreas
Trypsin
Pancreatic amylase
Lipases
Nucleases
insulin

26. Large intestine
Feces
Defecation
Mass movements

27. Digestion, absorption, transport
Carbohydrates – mono, di and poly saccharides
Lipids – triacylglycerol, saturated and unsaturated fats
Proteins – pepsin, trypsin, peptidases and amino acids

28. Water and minerals 9 L of water enters digestive tract per day
1.5 of those in food and drink
7.5 L from digestive secretions