the stomach and beyond
DESCRIPTION
The stomach and beyond. Digestion part 2. The stomach. Smooth muscles mix food (3-5 hours) Acid secretion denatures food Digestive enzymes begin to digest protein (fat, carbohydrate to lesser extent) Chyme is formed (food is liquefied); highly acidic. Very little absorption takes place. - PowerPoint PPT PresentationTRANSCRIPT
The stomach and beyond
Digestion part 2
The stomach• Smooth muscles mix food
(3-5 hours)• Acid secretion denatures
food• Digestive enzymes begin
to digest protein• (fat, carbohydrate to
lesser extent)• Chyme is formed (food is
liquefied); highly acidic
Very little absorption takes place
• Water, electrolytes, aspirin, alcohol
• Produces “intrinsic factor’ necessary for vitaminB12 absorption
Secretory structures of the stomach
• Cells in mucosa secrete:– Acid (parietal cells)– Mucus (goblet cells)– Pepsinogen (chief
cells)– hormones (G and D
cells)
Accessory organs: pancreas• Secretes digestive
enzymes into the small intestine– Pancreatic juice: amylase,
trypsin, lipase, etc.
• Secreted by acini (99% of pancreatic cells)
• Remaining 1% form islets of Langerhans and secrete insulin and glucagon
Liver and gall bladder
Diverse functions of liver
• Formation and secretion of bile• Metabolism of carbohydrates, lipids,
proteins• Formation of plasma proteins• Detoxification of blood• Storage of vitamins and minerals• Clearance of aged cells
Small intestine organization
Small intestine receives and produces secretions
• From pancreas and liver/gall bladder• Digestive enzymes
– Brush-border enzymes– Crypts of Lieberkühn
• Mucus– Goblet cells
• Hormones• Immune function
– Paneth cells
Large intestine
• Compaction of solid waste
• Bacterial breakdown of proteins; vitamin formation
• Absorption of water, ions, vitamins
• Defecation
Applications to health• Peptic ulcer- craterlike lesion caused by exposure to
gastric juices. • Vomiting- forcible expulsion of the contents of the upper
GI tract (stomach and duodenum).• Peritonitis- acute inflammation of the peritoneum.• Hepatitis- inflammation of the liver caused by viruses,
drugs, or chemicals.• Gallstones- crystallization of cholesterol due to
insufficient bile salts.• Appendicitis- inflammation of the appendix caused by an
obstruction of the lumen.