1. Digestive System

2. Functions Ingestion Secretion Mixing and propulsion Digestion
Absorption
Defecation

3. Digestive Organs GI tract: Accessory organs:
Mouth, Pharynx, Esophagus, Stomach, Small Intestine, Large Intestine, Anus
Accessory organs:
Teeth, Tongue, Salivary glands, Liver, Gallbladder, Pancreas

5. GI Tract Layers Mucosa Submucosa - areolar
Epithelium - Strat. Squamous to Simple Columnar
Lamina propria
Some smooth muscle
Submucosa - areolar
Muscularis - skeletal higher, smooth lower
Serosa - visceral peritoneum

7. Peritoneum Largest serous membrane Parietal and visceral
Five major folds:
Contain adipose tissue
Anchor major organs
Contain blood vessels and lymph nodes
Greater Omentum and Mesentary as examples

10. Macromolecule Review Carbohydrates - Mono- and Polysaccharides
Proteins - Amino acids form polypeptides
Lipids - Simple, complex, steroids
Nucleic Acids
What kinds of enzymes break down each group?

11. Mouth Ingestion Mastication and moistening
Beginning of chemical digestion
Movement of bolus to oropharynx

13. Accessory Organs in Mouth
Salivary glands - parotid, submandibular, sublingual
Tongue - papillae and lingual frenulum
Teeth
20 deciduous teeth, 32 permanent
Incisors (4), canines (2), bicuspid (4), molars (4-6?) per jaw

17. Mouth Mechanical Digestion Chemical Digestion Saliva also used to:
Mastication - Tongue, teeth, saliva  Bolus
Chemical Digestion
Salivary Amylase - starch  maltose, -dextrins
Lingual Lipase - Activated in stomach - Triglycerides  F.A.s and Diglycerides
Saliva also used to:
Destroy bacteria (Lysozyme, IgA)
Lubricate food (mucus)
Remove waste
Aid gustation (water)

18. Esophagus Laryngopharynx to stomach
Upper esophageal sphincter (skeletal muscle)
Lower esophageal sphincter (cardiac)
Passes through diaphragm at esophageal hiatus

19. Esophagus Deglutition (Swallowing) Peristalsis Wavelike contractions
Alternating bands of muscle

20. Stomach

21. Stomach Mechanical digestion Chemical digestion
Mixing waves - produce chyme and promote gastric emptying
Chemical digestion
Pepsin - proteins into smaller peptides
HCl - partial denaturation
Absorbs some water, ions, Fas, some drugs and alcohol

22. Gastric Glands Gastric Juice HCl Pepsin - protein digestion
kills microbes
converts pepsinogen to pepsin
Pepsin - protein digestion
Gastric lipase - Triglycerides  Fas and monoglycerides
Mucous - protects lining

23. Gastric glands

24. Pancreas Endocrine and exocrine gland
Pancreatic islets: insulin and glucagon (and others)
Acini: Pancreatic juice
Sodium bicabonate
Enzymes to digest all four macromolecule groups

25. Liver Secretion of Bile Bile stored in gall bladder Used for:
Excretion of Bilirubin
Emulsification of lipids by bile salts
Easier absorption of lipids
Excretion of drugs and hormones

26. Other Liver Functions Glycogen storage and glucose release/production
Lipid Metabolism
Protein metabolism - ease conversion of a.a., synthesize plasma proteins
Detoxification
Storage of vitamins/minerals
Phagocytosis of old blood cells and some bacteria
Activation of vitamin D

27. Small Intestine 90% of all absorption Aided by:
Length (10 ft avg)
Villi (1 mm)
Microvilli (1 um) - “Brush Border”
Monomers absorbed into capillaries or Lacteals

28. Small Intestine Duodenum, jejunum, ileum Intestinal glands
Duodenal glands - alkaline mucus - why?
Digestive enzymes along w/ pancreas
Circular folds - better absorption
Villi
Absorptive cells
Capillaries and lacteals
Microvilli

31. Small Intestine Chemical Digestion
Brush Border enzymes – all major groups
Intestinal Juices - water and mucus
Pancreatic Juice, Bile and Intestinal juice work in combination

32. Large Intestine Mechanical digestion Chemical digestion by bacteria
Haustral churning - contraction following distension
Peristalsis
Mass peristalsis - pushes contents into rectum
Chemical digestion by bacteria
Absorption of water, ions, and some vitamins

34. Defecation Feces formed in large intestine Defecation Reflex
Water, Inorganic salts, Bacteria and their products, Unabsorbed/Indigestible material, Epithelial cells
Defecation Reflex
Rectum distended
Stretch receptors  spinal cord
Parasymp  contraction of colon and rectum
Internal anal sphincter opens
External is voluntarily relaxed

35. pH Enzymes operate at optimal pH Saliva = 6.5 Gastric juice = 2
Pancreatic Juice =
Intestinal Juice = 7.6
pH adjusted by negative feedback (Buffers, Hormone release)

36. Hormones
Gastrin - gastric glands - gastric juice , gastric emptying , Sphincter control
Cholecystokinen (CCK) - s. Int - Pancreatic juice , Bile release , gastric emptying , satiation
Secretin - S. Int - Pancreatic Juice , Gastric Juice 