Download Digestion, Absorption and Transport

Digestion, Absorption
and Transport
The Gastrointestinal Tract
Basic anatomy of the GI tract:
– mouth
– esophagus
– stomach
– small intestine
– large intestine
– rectum
– anus
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson Learning
The Gastrointestinal Tract
Accessory organs
™ Salivary glands
™ Liver and gallbladder
™ Pancreas
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The Gastrointestinal Tract
™ Functions:
9 Ingestion
9 Transport
9 Secretion
9 Digestion
9 Absorption
9 Elimination
Digestive Tract
Physical Movement:
9 Peristalsis
9 Segmentation
Chemical Breakdown:
9 Enzymes
9 Hydrolysis
9 Other secretions
Digestive Tract
Mouth
¾ Tongue
¾ Teeth (Mastication)
Enzymes
¾ Salivary amylase
¾ Lingual lipase
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Digestive Tract
Pharynx
Epiglottis
Esophagus – transport food to stomach
– Esophageal sphincters
– Bolus
Digestive Tract
Stomach
™ Chyme
™ Pyloric sphincter
Secretions of Digestion
Saliva
– Salivary glands
Water, salts,
mucus,
enzymes
Muscular Action of Digestive Tract
Stomach mechanical action
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Stomach
Muscles
Esophegeal
Sphincter
Muscular Action of Digestive Tract
Sphincter contractions
– Reflux (heart burn)
Pyrolic
Sphincter
Digestive Tract
Esophageal sphincter
Stomach
™ Digestion factors:
9 Hydrochloric acid (protein; enzymes
activity; bacteria)
9 Pepsin (protein digestion)
9 Gastric lipase (Lipids)
9 Gastrin (stimulate gastric secretion
and movement)
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Secretions
of
Digestive
Tract
Digestive Tract
Small intestine:
¾ Duodenum (25 – 30 cm)
¾ Jejunum (120 cm)
¾ Ileum (150 cm)
Assisting Organs:
™ Liver & gallbladder
™ Pancreas
Secretions of Digestive Tract
Assisting Organs
Pancreas
– Pancreatic juice
Enzymes (trypsin, amylase, lipase,
chymotrypsin)
bicarbonate
Secretions of Digestive Tract
Assisting Organs
™Liver
– Bile
Emulsifier
™Gallbladder
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Muscular Action of Digestive Tract
Peristalsis
Peristalsis
Segmentation
Muscular Action of Digestive Tract - Segmentation
Digestive Tract
Large intestine = colon
– Ileocecal valve
– Appendix
Rectum
– Anus
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The Final Stage
Colon
Fermentation of undigested residues
(bacteria; vitamins K, B12, thiamin,
riboflavin, biotin, other B’
B’s; gases;
Short chain fatty acids; antibiotics protectants)
protectants)
Stool
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Digestion of a Sandwich
Digestion of a Sandwich
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Digestive Tract
Absorption – Modes of Transportation
Small intestine:
¾ Duodenum (25 – 30 cm)
¾ Jejunum (120 cm)
¾ Ileum (150 cm)
Assisting Organs:
™ Liver & gallbladder
™ Pancreas
Absorption in the Small Intestine
The Small Intestinal Villi
Villi
– Microvilli
– Capillaries and lacteals
– Chylomicrons
Crypts
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The Small Intestinal Villi, cont’
cont’d
Circulatory Systems
Vascular system
– Heart
– Arteries
– Capillaries
– Veins
Circulatory Systems
Vascular system
– Portal vein
– Hepatic vein
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The
Liver
Circulatory Systems
Lymphatic system
– Lymph
– Thoracic duct
Subclavian vein
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