chapter 45: processing food and nutrition the digestive system
TRANSCRIPT
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Chapter 45: Processing Food and Nutrition
The Digestive System
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Fig. 41-7
Ingestion Digestion Absorption Elimination
Undigestedmaterial
Chemical digestion(enzymatic hydrolysis)
Nutrientmoleculesenter bodycells
Smallmolecules
Mechanicaldigestion
Food
Piecesof food
1 2 3 4
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Fig. 41-10a
Cecum
Anus
Ascendingportion oflarge intestine
Gall-bladder
Smallintestine
Largeintestine
Smallintestine
Rectum
Pancreas
Liver
Salivary glands
TongueOral cavity
Pharynx
Esophagus
Sphincter
Stomach
Sphincter
Duodenum ofsmall intestine
Appendix
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Fig. 41-10b
Anus
Liver
Pancreas
Smallintestine
Largeintestine
Rectum
StomachGall-bladder
A schematic diagram of thehuman digestive system
Esophagus
Salivaryglands
Mouth
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Fig. 41-11-3
LarynxTrachea
Epiglottisup
Pharynx
Tongue
Glottis
Esophagus
Esophagealsphinctercontracted
Food
Tostomach
Tolungs
Epiglottisdown
Esophagealsphincterrelaxed
Glottis upand closed
Epiglottisup
Esophagealsphinctercontracted
Sphincterrelaxed
Relaxedmuscles
Contractedmuscles
Relaxedmuscles
Stomach
Glottisdownand open
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Fig. 41-12
Interior surfaceof stomach
Esophagus
Chief cells
Small intestine
Epithelium
Stomach
Sphincter
Parietal cell
Pepsinogen and HClare secreted.
HCl convertspepsinogen to pepsin.
Pepsin activatesmore pepsinogen.
Chief cell
Folds ofepithelialtissue
Pepsin
Sphincter
Pepsinogen
HCl
H+
Cl–
Parietal cells
Mucus cells
Gastric gland
1
2
2
3
3
1
5 µm
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Fig. 41-13
Oral cavity,pharynx,esophagus
Stomach
Lumen ofsmall intes-tine
Epitheliumof smallintestine(brushborder)
Carbohydrate digestion
Polysaccharides
Smaller polysaccharides,maltose
Polysaccharides
Maltose and otherdisaccharides
Disaccharides
Protein digestion Nucleic acid digestion Fat digestion
Proteins
Small polypeptides
Pepsin
Pancreatic amylases
Salivary amylase
Disaccharidases
Monosaccharides
Small peptides
Amino acids
Amino acids
Polypeptides
Smallerpolypeptides
Pancreatic trypsin andchymotrypsin
Pancreatic carboxypeptidase
Dipeptidases, carboxypeptidase,and aminopeptidase
DNA, RNA
Pancreatic nucleases
Fat globules
NucleotidesFat droplets
Nucleosides
Nitrogenous bases,sugars, phosphates
Nucleotidases
Nucleosidasesandphosphatases
Glycerol, fattyacids, monoglycerides
Bile salts
Pancreatic lipase
(starch, glycogen) (sucrose, lactose)
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Fig. 41-15a
Muscle layers
Vein carrying bloodto hepatic portal vein
Villi
Intestinal wall
Key
Nutrientabsorption
Largecircularfolds
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Fig. 41-15bMicrovilli (brushborder) at apical(lumenal) surface
Key
Nutrientabsorption
Bloodcapillaries
Epithelialcells
Villi
Lymphvessel
Basal surface
LactealEpithelial cells
Lumen
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Fig. 41-21
Homeostasis:90 mg glucose/100 mL blood
Stimulus:Blood glucose
level risesafter eating.
Stimulus:Blood glucose
level dropsbelow set point.