Lecture 1: Membrane and electric 2023 Flashcards
What component of a circuit does the membrane resemble
a capacitor
2 plates –> membrane bilayer
build up/storage of charge
distance and area are proportional to the level of capacitance in plate capacitors
plasma mb capacitance is affected by SA and distance(mb thickness) but doesn’t change much
separated by 5nm generated large electric field
bilayer allows for segregation of environments hydrophobic inside, storage of charge
the resistors/conductors in cell
ion channels
same thing but inverse relationship
conductance of channels is gK
The source of power in the cell circuit model
electron motive force, electrochemical gradients
Potential Energy
voltage
measuring single channel current
down, depolarization current in the direction away from the electrode
Factors affecting membrane permeability
size, polarity of the molecules
polarity»_space; size
hydrophobic environments are highly impermeable ti charged ions regardless of size
non polar hydrophobic molecules
slips through easily,
ex. O2, CO2, N2, steroid hormones
small uncharged molecules
slightly permeable
ex. h2o , urea, glycerol
large uncharge polar molecules
barely making it
ex. sucrose, glucose
ions (charged molecules)
aint no way, without the presence of a protein channel
ex. H+, Na+ K+, Cl-
active forms of transport
require energy, going ion the opposite direction of gradient, require a protein complex usually transporter of some sort
passive transport
no E requirement, can require protein complex but not always
- simple diffusion
-channel mediated
-transporter mediated
“openness” of channel
resistance in ohms
voltage
potential difference can also be written as E in volts
conductance
inverse of resistance, in Siemens
