Block 2 Lecture 23 Flashcards
what are pores
a diffusional pathway that is always open
what are the functions of channels
- mediate salt flux that leads to water flux
- modulate membrane potential
- modulate cytoplasmic Ca2+
what is gating
the conformational change of the channel protein opening
what are non gated channels
constitutively active (K+ leak channels) and their open and closed status
what is conductance measured in
siemens (ampere/volt)
what is current measured in
amperes (coulombs/sec)
how do you calculate ions/sec?
driving force times conductance
what can you not predict in channels
the number of particles that will pass through the channel when its open
in a patch clamp trace what happens with cations
a downward deflection represents positive particles entering the cell, an upward deflection represents positive particles leaving the cell
in a patch clamp trace what happens with anions
a downward deflections represents negative particles leaving the cell, an upward deflection represents positive particles entering the cell
what are the 2 driving forces for net water flux
hydrostatic pressure and osmosis
what is the apical membrane chloride channel activated by
Ca2+
what prompts the release of Ca2+
AcH
