Chapter 5c

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Chapter 5c. Membrane Dynamics. The Body Is Mostly Water. Distribution of water volume in the three body fluid compartments 1 liter water weighs 1 kg or 2.2 lbs 70 kg X 60% = 42 liters for avg 154 lb male. Figure 5-25. Aquaporin. - PowerPoint PPT Presentation

Text of Chapter 5c

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Chapter 5cMembrane Dynamics1Figure 5-25The Body Is Mostly WaterDistribution of water volume in the three body fluid compartments1 liter water weighs 1 kg or 2.2 lbs70 kg X 60% = 42 liters for avg 154 lb male

2Aquaporin

Moves freely through cells by special channels of aquaporinFigure 5-26Osmosis and Osmotic PressureOsmolarity describes the number of particles in solution

VolumesequalOsmotic pressure isthe pressure that must beapplied to B to oppose osmosis.VolumeincreasedVolumedecreasedTwo compartments areseparated by a membrane that is permeable to water but not glucose.Water moves byosmosis into the moreconcentrated solution. GlucosemoleculesSelectivelypermeablemembraneAB132

4Table 5-5Osmolarity: Comparing Solutions

Hyper / Hypo / Iso are relative termsOsmolarity is total particles in solutionNormal Human body around 280 300 mOsM

5Table 5-6TonicitySolute concentration = tonicityTonicity describes the volume change of a cell placed in a solution

6Figure 5-27aTonicityTonicity depends on the relative concentrations of nonpenetrating solutes

7Figure 5-27bTonicityTonicity depends on nonpenetrating solutes only

8Figure 5-28TonicityTonicity depends on nonpenetrating solutes only

(a)(b)(c)(d)CellSolutionH2O9Plasmolysis and CrenationRBCs

Table 5-7Osmolarity and Tonicity

11Table 5-8Intravenous Solutions

12Electricity ReviewLaw of conservation of electrical chargesOpposite charges attract; like charges repel each otherSeparating positive charges from negative charges requires energyConductor versus insulator13Figure 5-29bSeparation of Electrical ChargesResting membrane potential is the electrical gradient between ECF and ICF

(b) Cell and solution in chemical and electrical disequilbrium.Intracellular fluidExtracellular fluid14Figure 5-29cSeparation of Electrical ChargesResting membrane potential is the electrical gradient between ECF and ICF

15Figure 5-30Measuring Membrane Potential Difference

The voltmeterCellThe chart recorderSaline bathA recording electrodeInputThe ground ( ) or referenceelectrodeOutput16Figure 5-31aPotassium Equilibrium Potential

Artificial cell(a)17Figure 5-31bPotassium Equilibrium Potential

(b)K+ leak channel18Figure 5-31cPotassium Equilibrium PotentialResting membrane potential is due mostly to potassiumK+ can exit due to [ ] gradient, but electrical gradient will pull back; when equal resting membrane potential

Concentrationgradient Electricalgradient (c)19Figure 5-32Sodium Equilibrium PotentialSingle ion can be calculated using the Nernst EquationEion = 61/z log ([ion] out / [ion] in)

150 mM0 mV15 mM+60 mV20Figure 5-33Resting Membrane Potential

Extracellular fluid0 mVIntracellular fluid-70 mV21Figure 5-34Changes in Membrane PotentialTerminology associated with changes in membrane potentialPLAYInteractive Physiology Animation: Nervous I: The Membrane Potential

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1Low glucose levels in blood.No insulinsecretionMetabolismslows.ATPdecreases.ATPMetabolismGlucoseCell at restingmembrane potential.No insulin is released.KATPchannels open. Insulin in secretory vesiclesK+ leaks outof cellVoltage-gated Ca2+ channel closedGLUT transporter(a) Beta cell at rest2345Figure 5-35aInsulin Secretion and Membrane Transport Processes23

1Low glucose levels in blood.Glucose(a) Beta cell at restFigure 5-35a, step 1Insulin Secretion and Membrane Transport Processes24

1Low glucose levels in blood.Metabolismslows.MetabolismGlucoseGLUT transporter(a) Beta cell at rest2Figure 5-35a, steps 12Insulin Secretion and Membrane Transport Processes25

1Low glucose levels in blood.Metabolismslows.ATPdecreases.ATPMetabolismGlucoseGLUT transporter(a) Beta cell at rest23Figure 5-35a, steps 13Insulin Secretion and Membrane Transport Processes26

1Low glucose levels in blood.Metabolismslows.ATPdecreases.ATPMetabolismGlucoseKATPchannels open. K+ leaks outof cellGLUT transporter(a) Beta cell at rest234Figure 5-35a, steps 14Insulin Secretion and Membrane Transport Processes27

1Low glucose levels in blood.No insulinsecretionMetabolismslows.ATPdecreases.ATPMetabolismGlucoseCell at restingmembrane potential.No insulin is released.KATPchannels open. Insulin in secretory vesiclesK+ leaks outof cellVoltage-gated Ca2+ channel closedGLUT transporter(a) Beta cell at rest2345Figure 5-35a, steps 15Insulin Secretion and Membrane Transport Processes28

1 Glycolysisand citric acid cycleATPCa2+ signal triggersexocytosis and insulin is secreted.Ca2+Ca2+High glucose levels in blood.Metabolismincreases.ATPincreases.GlucoseCell depolarizes andcalcium channelsopen.KATP channels close.Ca2+ entry acts as anintracellularsignal.GLUT transporter(b) Beta cell secretes insulin234567Figure 5-35bInsulin Secretion and Membrane Transport Processes29

1High glucose levels in blood.(b) Beta cell secretes insulinFigure 5-35b, step 1Insulin Secretion and Membrane Transport ProcessesGlucose30

1 Glycolysisand citric acid cycleHigh glucose levels in blood.GLUT transporter(b) Beta cell secretes insulin2Figure 5-35b, steps 12Insulin Secretion and Membrane Transport ProcessesGlucoseMetabolismincreases.31

1 Glycolysisand citric acid cycleATPHigh glucose levels in blood.GLUT transporter(b) Beta cell secretes insulin23Figure 5-35b, steps 13Insulin Secretion and Membrane Transport ProcessesGlucoseMetabolismincreases.ATPincreases.32

1 Glycolysisand citric acid cycleATPHigh glucose levels in blood.KATP channels close.GLUT transporter(b) Beta cell secretes insulin234Figure 5-35b, steps 14Insulin Secretion and Membrane Transport ProcessesGlucoseMetabolismincreases.ATPincreases.33

1 Glycolysisand citric acid cycleATPCa2+High glucose levels in blood.Cell depolarizes andcalcium channelsopen.KATP channels close.GLUT transporter(b) Beta cell secretes insulin2345Figure 5-35b, steps 15Insulin Secretion and Membrane Transport ProcessesGlucoseMetabolismincreases.ATPincreases.34

1 Glycolysisand citric acid cycleATPCa2+Ca2+High glucose levels in blood.Cell depolarizes andcalcium channelsopen.KATP channels close.Ca2+ entry acts as anintracellularsignal.GLUT transporter(b) Beta cell secretes insulin23456Figure 5-35b, steps 16Insulin Secretion and Membrane Transport ProcessesGlucoseMetabolismincreases.ATPincreases.35

1 Glycolysisand citric acid cycleATPCa2+ signal triggersexocytosis and insulin is secreted.Ca2+Ca2+High glucose levels in blood.Cell depolarizes andcalcium channelsopen.KATP channels close.Ca2+ entry acts as anintracellularsignal.GLUT transporter(b) Beta cell secretes insulin234567Figure 5-35b, steps 17Insulin Secretion and Membrane Transport ProcessesGlucoseMetabolismincreases.ATPincreases.36SummaryMass balance and homeostasisLaw of mass balanceExcretionMetabolismClearanceChemical disequilibriumElectrical disequilibriumOsmotic equilibrium37SummaryDiffusionProtein-mediated transportRoles of membrane proteinsChannel proteinsCarrier proteinsActive transport38SummaryVesicular transportPhagocytosisEndocytosisExocytosisTransepithelial transport39SummaryOsmosis and tonicityOsmolarityNonpenetrating solutes TonicityThe resting membrane potentialInsulin secretion40