Digestion and Absorption Johnson Chap Jack L. Leonard 2004
Johnson Chap Epithelial Cell Structure
Johnson Chap Cell membrane Glycocalyx Transport carrier ExtrinsicenzymeIntrinsicenzymeMicrovillus
Johnson Chap ,4 link 1,6 link -limit dextrins amylase maltotriose maltose amylopectin Initial breakdown of starch
Johnson Chap Amylose
Amylopectin
Cellulose
Sucrose
Lactose
Maltose
glucose galactose fructose sucrose lactose -limit dextrins (G5-G9) Malto-oligosaccharides Starchglycogen amylase glucose Glucosetransporter Na + G GaGF G-G-G-G G-G-G 40% G 2 25% G 3 5% G 4 -G 9 Lactase Glucosecarrier Fructosecarrier Sucrase -dextrinase Glucosecarrier Glucoamylase Brush Border CHO enzymes
Johnson Chap Enzyme Primary Action Endopeptidases Hydrolyze(s) interior peptide bonds containing Pepsin Pepsin Aromatic amino acids Trypsin Trypsin Basic amino acids Chymotrypsin Chymotrypsin Aromatic amino acids—leu, met, gln—C-terminal residue Elastase Elastase Neutral aliphatic amino acids Exopeptidases Hydrolyze(s) external peptide bonds containing Carboxypeptidase A Carboxypeptidase A Aromatic and neutral amino acids—aliphatic AA at C-terminus Carboxypeptidase B Carboxypeptidase B Aromatic and neutral amino acids—basic AA at C-terminus Principal luminal proteases
Johnson Chap Principal luminal absorption
Johnson Chap Intact Protein Absorption
Johnson Chap Principal luminal absorption
Johnson Chap Digestion of Fat
Johnson Chap Absorption of Sugars
Johnson Chap Carrier AA transported Neutral ( -amino- monocarboxylic) Aromatic (Phe, Tyr, Trp) Aliphatic (Gly, Ala, Val, Leu, Ile, Ser His, Met, Asn, Gln, Cys, Pro, OH-Pro Basic (cationic) Lys, Arg, Orn, Cys Acidic (anionic) Glu, Asp, SeC Imino Pro, OH-Pro, GABA, Tau, Gly, other AA with amino groups in or positions Amino Acid Carrier Systems
Johnson Chap Absorption of Fluid and Ions Cl K+K+K+K+ ATP Na + Lumen Serosal surface glucose Na + K+K+K+K+ ATP H+H+H+H+ + HCO 3 - H+H+H+H+ H 2 CO 3 H2OH2OH2OH2O CO 2 + CO 2 metabolism + HCO 3 - H+H+H+H+ H 2 CO 3 H2OH2OH2OH2O CO 2 + HCO 3 - Cl -
Johnson Chap Na ~ ~ ~ H K Na K K [K~155 mM] 32 mV Na mV mV 47 mV -15 mV + - Serosa Mucosa