TRANSPORT ACROSS MEMBRANES
HOW DO WE CHARACTERIZE TRANSPORT ACROSS MEMBRANES?
THE STEADY STATE
HOMEOSTASIS IS LIKE A STEADY STATE AWAY FROM EQUILIBRIUM
PPT Slide
THE RESTING CELL
EQUILIBRIUM RESULTS FROM ISOLATING THE SYSTEM
EQUILIBRIUM FOR A CELL MEANS DEATH
DEFINITION OF A FLOW
MEASUREMENT OF A FLOW
TWO MAJOR TYPES OF TRANSPORT
Passive Transport
Diffusion
Diffusion across a permeable membrane
Impermeable membrane
MEASUREMENT OF A PERMEABILTY
FICK’S LAW FOR DIFFUSION
OIL/WATER PARTITION: THE “KITCHEN” EXPERIMENT
PERMEABILITY AND OIL/WATER PARTITION
THE MAJOR BARRIER IN THE CELL MEMBRANE IS LIPID
PARTITION AND PERMEABILITY
DIFFUSION OCCURS IN THE MEMBRANE
Bulk Flow
BULK FLOW
POISEUILLE’S LAW FOR BULK FLOW
Current Flow
OHM’S LAW FOR CURRENT FLOW
IONS MOVE WITH THEIR HYDRATION SHELLS
MOBILITY OF IONS DEPENDS ON HYDRATED SIZE
ELECTRONEUTRAL DIFFUSSION
ELECTRONEUTRAL EXCHANGE
THE ORIGIN OF BIOELECTRICITY
Osmosis
POISEUILLE’S LAW FOR BULK FLOW WHEN OSMOSIS IS PRESENT
A GENERALISATION FOR ALL LINEAR FLOW PROCESSES
A SUMMARY OF ALL LINEAR FLOW PROCESSES
Facilitated Diffusion
ACTIVE TRANSPORT REQUIRES AN INPUT OF ENERGY
ACTIVE TRANSPORT
Email: mikulecky@gems.vcu.edu
Home Page: http://views.vcu.edu/~mikuleck/