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