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Digestive Hormones. Gastrin family Gastrin and CCK Secretin family Secretin, VIP, GIP, and GLP-1 Others Motilin. PLAY. Animation: Digestive System: Control of the Digestive System. THE DIGESTIVE HORMONES. Digestion and Absorption. A villus and a crypt in the small intestine. - PowerPoint PPT Presentation
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Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Digestive Hormones
Gastrin family Gastrin and CCK
Secretin family Secretin, VIP, GIP, and GLP-1
Others Motilin
Animation: Digestive System: Control of the Digestive SystemPLAY
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
THE DIGESTIVE HORMONESHormone Secreted By Target Effects on Motility Stimulus for
ReleaseRelease
Inhibited by
Gastrin G cells in stomach
parietal cells None Peptides and amino acids in lumen; gastrin releasing peptide and Ach in nervous reflexes
pH<1.5; somatostatin
CCK Endocrine cells of small intestine; neurons of brain and gut
Gallbladder, pancreas, gastric smooth muscle
Stimulates gallbladder contraction for bile release; inhibits gastric emptying; promotes intestinal motility
Fatty acids and some amino acids
Somatostatin
Secretin Endocrine cells in small intestine
Pancreas, stomach
Inhibits gastric emptying
Acid in small intestine
Somatostatin
Gastric Inhibitory Peptide (GIP)
Endocrine cells in small intestine
Beta cells of endocrine pancreas
None Glucose, fatty acids, and amino acids in small intestine
NA
Motilin Endocrine cells in small intestine
Smooth muscle of antrum and duodenum
Stimulates migrating motor complex
Fasting: periodic release every 1.5-2 hours by neural stimulus
NA
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 21-13
Digestion and Absorption
A villus and a crypt in the small intestine
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 21-14
Carbohydrate Digestion: Breakdown to monosaccharide, which can be absorbed
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 21-15
Carbohydrate Absorption in the Small Intestine
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 21-16
Enzymes for Protein Digestion
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 21-17
Peptide Absorption
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 21-18
Digestion and Absorption
Triglycerides digest into monoglycerides and free fatty acids
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 21-19
Digestion and Absorption of Fats
Capillary
Cells ofsmall
intestine
Interstitialfluid
Triglycerides + cholesterol + protein
Lymphto
venacava
Lacteal
Golgiapparatus
SmoothER
Chylomicron
Lumen ofsmall intestine
Large fat dropletsfrom stomach
Lipaseand colipase
Emulsion
Bile saltsrecycled
Micelles
Bile saltsfrom liver
Monoglycerides and fatty acids move out of micelles and enter cells by diffusion.
Pancreatic lipase and colipase break down fats into monoglycerides and fatty acids stored in micelles.
Chylomicrons are released into the lymphatic system.
Absorbed fats combine with cholesterol and proteins in the intestinal cells to form chylomicrons.
Bile salts from liver coat fat droplets.
Cholesterol is transported into cells by a membrane transporter.
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2
3a
3b
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5
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2
3a3b
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5
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 21-20
Digestion and Absorption
The role of bile salts in emulsions and micelles
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Digestion and Absorption
Nucleic acids are digested into nitrogenous bases and monosaccharides
Intestine absorbs vitamins and minerals Fat-soluble vitamins (A, D, E, K) absorbed with fats in
small intestines
Water-soluble vitamins (C, B vitamins) absorbed by mediated transport
Exception: Vitamin B12 when complexed to intrinsic factor, secreted in the stomach, and absorbed in ileum
Minerals absorbed by active transport
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 21-21
Digestion and Absorption
NaCl reabsorption in the small intestine and colon
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 21-22
Digestion and Absorption
Summary of motility, secretion, digestion, and absorption in different regions of the digestive system
Animation: Digestive System: Digestion and AbsorptionPLAY
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
3 PHASES OF FOOD PROCESSING
1. Cephalic Phase
2. Gastric Phase
3. Intestinal Phase
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
The Cephalic Phase
Chemical and mechanical digestion begins in the mouth
Salivary secretion under autonomic control Softens and lubricates food
Chemical digestion: Salivary amylase and some lipase
Saliva is protection as well
Chewing: mastication
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Swallowing Reflex
Figure 21-24, step 1
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Swallowing Reflex
Figure 21-24, step 2
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Swallowing Reflex
Figure 21-24, step 3
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 21-24
Swallowing Reflex
