Download Digestion

Digestion, Absorption
and Transport
Digestion
• Basic anatomy of the GI tract
–mouth  esophagus  stomach
 small intestine  large
intestine  rectum  anus
–lumen
GI Tract
Anatomy
Digestion
• Mouth
–Tongue
–Teeth
•Mastication (chewing)
The Teeth
Digestion
• Pharynx
• Epiglottis
• Esophagus
–Esophageal sphincters
–Bolus
Digestion
• Stomach
–Chyme
–Pyloric sphincter
Stomach
Muscles
Digestion
• Small intestine
–Duodenum
–Jejunum
–Ileum
Digestion
• Gallbladder
• Pancreas
Digestion
• Large intestine = colon
–Ileocecal valve
–Appendix
• Rectum
–Anus
Peristalsis & Segmentation
Muscular Action of Digestion
• Segmentation
Muscular Action of Digestion
• Sphincter contractions
–Reflux
Secretions of Digestion
• Catalysts
–Hydrolysis
–Digestive enzymes
Secretions of Digestion
• Saliva
–Salivary glands
•Water, salts,
mucus,
enzymes
Secretions
of Digestion
• Stomach
–Gastric juice
–Gastric glands
•Water, enzymes,
hydrochloric acid
(HCl)
Secretions of Digestion
• Stomach
–Goblet cells
•Mucus
Secretions of Digestion
• Pancreas
–Pancreatic juice
•Enzymes, bicarbonate
Secretions of Digestion
• Liver
–Bile
•Emulsifier
• Gallbladder
The Final Stage
• Stools
• Colon
–Fermentation of undigested
residues
Digestion of a Sandwich (1)
Digestion of a Sandwich (2)
Absorption
Absorption in the
Small Intestine
• Villi
–Microvilli
–Capillaries and lacteals
–Chylomicrons
• Crypts
Small Intestinal Villi
The Small Intestinal Villi, cont’d
Circulatory Systems
• Vascular system
–Heart
–Arteries
–Capillaries
–Veins
–Lymph system-not part of it!
Circulatory Systems
• Vascular system
–Portal vein-blood from GI tract
toward capillaries in the liver.
–Hepatic vein-liver to heart.
The Liver
Regulation of Digest.
• Hormones
–Gastrin-controls secretion of
gastric acid
–Secretin-facilitates secretion of
pancreatic juice (bicarbonate)
–Cholecystokinin = CCK (bile
release from gall bladder, slows
GI motility)