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Basic Principles of Transport

Handbook of Physiology, Cell Physiology

  1. Robert I. Macey1,
  2. Teresa F. Moura2

Published Online: 1 JAN 2011

DOI: 10.1002/cphy.cp140106

Comprehensive Physiology

Comprehensive Physiology

How to Cite

Macey, R. I. and Moura, T. F. 2011. Basic Principles of Transport. Comprehensive Physiology. 181–259.

Author Information

  1. 1

    Department of Molecular and Cell Biology, University of California, Berkeley, California

  2. 2

    Faculdade de Ciěncias e Tecnologia UNL, and Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Lisbon, Portugal

Publication History

  1. Published Online: 1 JAN 2011

Abstract

The sections in this article are:

  • 1
    Thermodynamics
    • 1.1
      Maximal Work Is Attained on Reversible Paths
    • 1.2
      Changes in Free Energy Are Obtained from Chemical Potentials: Free Energy per Mole
    • 1.3
      Solutes in Phase Equilibrium
    • 1.4
      Osmotic Equilibrium
    • 1.5
      Chemiosmotic Coupling
  • 2
    Diffusion
    • 2.1
      Flux Is Proportional to the Concentration Gradient: Fick's First Law
    • 2.2
      Conservation of Matter: Fick's Second Law
    • 2.3
      Progress of Diffusion: Mean Square Displacement = 2 Dt
    • 2.4
      Randomly Diffusing Molecules Spread Out in a Normal Distribution
    • 2.5
      The Diffusion Front, Where Solute Depletion Ends and Accumulation Begins, Moves as inline image
    • 2.6
      Diffusion Transients in Thin Membranes Are Very Rapid
    • 2.7
      Permeation through Membranes Takes Place in At Least Three Steps
    • 2.8
      The Exchange Time for Filling or Emptying of Cells Equals V/PA
    • 2.9
      In Simple Exponential Processes, the Time Constant = the Mean Residence Time
    • 2.10
      Cytoplasmic Diffusion Transients Are Rapid
    • 2.11
      Unstirred Layers Can Be a Significant Barrier
    • 2.12
      Membrane Diffusion Is Assumed to Be Rate-Limiting for Plasma Membranes
    • 2.13
      Selective Permeability of Lipid Bilayers Is Determined Primarily by Solubility
  • 3
    Water Transport
    • 3.1
      Water Transport Can Be Driven by Three Different Gradients
    • 3.2
      In Lipid Membranes Water Transport Occurs by Solubility-Diffusion Mechanism, with Pf = Posm = Pd
    • 3.3
      Osmotic Gradients Generate Hydraulic Pressure Gradients in Aqueous Channels
    • 3.4
      In Narrow Channels the Ratio Posmotic/Pdiffusion = the Number of Water Molecules Contained within the Channel
    • 3.5
      Coupling of Solute and Solvent Transport Is Described by the Kedem-Katchalsky Equations
  • 4
    Ionic Diffusion
    • 4.1
      Diffusion with Superimposed Drift Due to External Forces
    • 4.2
      Ions Transported by Simple Diffusion Follow the Ussing Flux Ratio Relation
    • 4.3
      Bulk Solutions Carry No Net Charge
    • 4.4
      The Constant Field Is a Convenient Idealization
    • 4.5
      Conductance Depends on Ionic Concentrations
    • 4.6
      Permeability Ratios Can Be Measured by Changes in Membrane Potential
    • 4.7
      An Electrogenic Pump Contributes to Ψm
    • 4.8
      Channels Can Be Incorporated into the Nernst-Planck Formulation
  • 5
    Energy Barriers
    • 5.1
      The Born Energy Estimates the Work Required to Transfer an Ion from One Medium to Another
    • 5.2
      Born Energy, Image Forces, Dipole Potentials, and Hydrophobic Interactions Contribute to the Energy Barriers of Lipid Bilayers
    • 5.3
      Solvation Energies Are Important Determinants of Channel Accessibility
    • 5.4
      Surface Potentials Modify the Transmembrane Potential as Well as Local Ion Concentrations
    • 5.5
      Transport across Energy Barriers
    • 5.6
      Eyring Rate Theory: Rate Constants Depend on Ψ
    • 5.7
      Kinetic Approaches
  • 6
    Channels
    • 6.1
      Single-Occupancy Channels with Binding Sites Show Saturation Kinetics
    • 6.2
      Competition, Unidirectional Flux, and the Ussing Flux Ratio
    • 6.3
      Single-Occupancy Channels: Voltage Dependence in Symmetric Channels
    • 6.4
      Single-Occupancy-Channel Results Can Be Generalized to N Sites
    • 6.5
      Multiple Occupancy
  • 7
    Simple Carriers
    • 7.1
      Net Flux
    • 7.2
      Unidirectional Flux
    • 7.3
      Equilibrium at the Boundaries
    • 7.4
      Rate-Limiting Steps at the Boundaries
    • 7.5
      Energy-driven Simple Carrier Systems
  • 8
    Cotransport
    • 8.1
      Thermodynamics: Cotransport Can Move Solutes “Uphill”
    • 8.2
      Kinetic Description
    • 8.3
      General Net Flux
    • 8.4
      Unidirectional Fluxes
    • 8.5
      Kinetics of Simultaneous Binding of mA and nB Resembles Simple Carrier Kinetics When Carrier Concentrations Are Replaced with the Product AmBn
    • 8.6
      Relations between the Net Flux Equation Parameters and the Michaelis-Menten—type Parameters for 1:1 Stoichiometry
  • 9
    Countertransport
    • 9.1
      Thermodynamics
    • 9.2
      Kinetic Models
    • 9.3
      Ping-Pong Model
    • 9.4
      Sequential Model
    • 9.5
      Generalization to m-n Stoichiometry for Simultaneous Binding
  • 10
    Fluctuating Barriers: Channels and Carriers
    • 10.1
      Channel Transport Properties Depend on the Rate of Transition between the Conformations
    • 10.2
      Channels with Fluctuating Barriers Do Not Show Michaelis-Menten Kinetics
    • 10.3
      Channels with Fluctuating Barriers Can Show Carrier Kinetics