digestion and absorption johnson chap. 34-35 jack l. leonard 2004
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Digestion and AbsorptionDigestion and Absorption
Johnson Chap. 34-35Johnson Chap. 34-35
Jack L. Leonard 2004Jack L. Leonard 2004
Johnson Chap. 34-35Johnson Chap. 34-35
Epithelial Cell StructureEpithelial Cell Structure
Johnson Chap. 34-35Johnson Chap. 34-35
Cell membraneCell membrane
GlycocalyxGlycocalyx
Transport carrierTransport carrier
ExtrinsicExtrinsicenzymeenzyme
IntrinsicIntrinsicenzymeenzyme
Microvillus Microvillus
Johnson Chap. 34-35Johnson Chap. 34-35
1,4 link1,4 link
1,6 link1,6 link
-limit dextrins-limit dextrins
amylaseamylase
maltotriosemaltotriose
maltosemaltose
amylopectinamylopectin
Initial breakdown of starch Initial breakdown of starch
Johnson Chap. 34-35Johnson Chap. 34-35
AmyloseAmylose
Johnson Chap. 34-35Johnson Chap. 34-35
Amylopectin Amylopectin
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CelluloseCellulose
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Sucrose Sucrose
Johnson Chap. 34-35Johnson Chap. 34-35
LactoseLactose
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Maltose Maltose
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glucoseglucose
galactosegalactose fructosefructose
sucrosesucroselactoselactose
-limit dextrins-limit dextrins(G5-G9)(G5-G9)
Malto-oligosaccharidesMalto-oligosaccharides
StarchStarchglycogenglycogen
amylaseamylase
glucoseglucose
GlucoseGlucosetransportertransporter
NaNa++NaNa++
GG GaGa GGFF G-G-G-GG-G-G-G
G-G
-GG
-G-G
40% G40% G22
25% G25% G33
5% G5% G44-G-G99
LactaseLactase GlucoseGlucosecarriercarrier
FructoseFructosecarriercarrier SucraseSucrase
-dextrinase-dextrinase
GlucoseGlucosecarriercarrier
GlucoamylaseGlucoamylase
Brush Border CHO enzymes Brush Border CHO enzymes
Johnson Chap. 34-35Johnson Chap. 34-35
EnzymeEnzyme Primary ActionPrimary ActionEndopeptidasesEndopeptidases Hydrolyze(s) interior peptide Hydrolyze(s) interior peptide
bonds containingbonds containing
PepsinPepsin Aromatic amino acidsAromatic amino acids
TrypsinTrypsin Basic amino acidsBasic amino acids
ChymotrypsinChymotrypsin Aromatic amino acids—leu, met, Aromatic amino acids—leu, met, gln—C-terminal residuegln—C-terminal residue
ElastaseElastase Neutral aliphatic amino acidsNeutral aliphatic amino acids
ExopeptidasesExopeptidases Hydrolyze(s) external peptide Hydrolyze(s) external peptide bonds containingbonds containing
Carboxypeptidase ACarboxypeptidase A Aromatic and neutral amino acidsAromatic and neutral amino acids—aliphatic AA at C-terminus—aliphatic AA at C-terminus
Carboxypeptidase BCarboxypeptidase B Aromatic and neutral amino acidsAromatic and neutral amino acids—basic AA at C-terminus—basic AA at C-terminus
Principal luminal proteases Principal luminal proteases
Johnson Chap. 34-35Johnson Chap. 34-35
Principal luminal absorption Principal luminal absorption
Johnson Chap. 34-35Johnson Chap. 34-35
Intact Protein Absorption Intact Protein Absorption
Johnson Chap. 34-35Johnson Chap. 34-35
Principal luminal absorption Principal luminal absorption
Johnson Chap. 34-35Johnson Chap. 34-35http://www.colorado.edu/epob/epob1220lynch/imagehttp://www.colorado.edu/epob/epob1220lynch/image
Digestion of Fat Digestion of Fat
Johnson Chap. 34-35Johnson Chap. 34-35http://www.rpi.edu/dept/chem-eng/Biotech-Environ/Membranes/bauerphttp://www.rpi.edu/dept/chem-eng/Biotech-Environ/Membranes/bauerp
Absorption of Sugars Absorption of Sugars
Johnson Chap. 34-35Johnson Chap. 34-35
CarrierCarrier AA transportedAA transported
Neutral Neutral ((-amino--amino-monocarboxylicmonocarboxylic))
Aromatic (Phe, Tyr, Trp)Aromatic (Phe, Tyr, Trp)
Aliphatic (Gly, Ala, Val, Leu, Aliphatic (Gly, Ala, Val, Leu, Ile, SerIle, Ser
His, Met, Asn, Gln, Cys, Pro, His, Met, Asn, Gln, Cys, Pro, OH-ProOH-Pro
Basic Basic (cationic)(cationic) Lys, Arg, Orn, CysLys, Arg, Orn, Cys
Acidic Acidic (anionic)(anionic) Glu, Asp, SeCGlu, Asp, SeC
IminoImino Pro, OH-Pro, GABA, Tau, Gly, Pro, OH-Pro, GABA, Tau, Gly, other AA with amino groups in other AA with amino groups in or or positions positions
Amino Acid Carrier SystemsAmino Acid Carrier Systems
Johnson Chap. 34-35Johnson Chap. 34-35
Absorption of Fluid and IonsAbsorption of Fluid and Ions
ClCl
KK++
ATPATP
NaNa++
NaNa++
LumenLumen
Serosal surfaceSerosal surface
glucoseglucoseNaNa++
KK++
AT
PA
TP
NaNa++
HH++
+ HCO+ HCO33--HH++ HH22COCO33
HH22OOCOCO22 + +
COCO22
metabolismmetabolism
+ HCO+ HCO33--
HH++
HH22COCO33
HH22OOCOCO22 + +
HCOHCO33--
ClCl--
Johnson Chap. 34-35Johnson Chap. 34-35
NaNa
~~
~~
~~HH
KK
NaNa
KK
KK[K~155 mM][K~155 mM]
32 mV32 mV
NaNa
-- ++
56 mV56 mV
--++
41 mV41 mV
47 mV47 mV
-15 mV-15 mV ++--
SerosaSerosaMucosaMucosa