Intro to CNS Flashcards
Biological membranes are essentially impermeable to ions
This is because the internal region of the bilayer is very hydrophobic and ions are hydrated by water
Protein families have evolved that function to allow ionic passage across the membrane
- ATPase driven pumps
- Transporters
- Ion channels: some generalities
a) Integral membrane proteins
b) Multiple membrane-spanning domains
c) Form a hydrophobic channel in the center
ion channels
Selective for ions and regulated by :
changes in the cellular environment
Ion Channels have______gene products; multiple subunits and are Glycosylated on the
Multiple
extracellular side
Ion Channels have Consensus sequences for
kinases
non-gated, always open
Passive:
gated; the closed and open states of the channel are regulated
Active
Gating mechanisms
Membrane potential differences
small extracellular molecules (NT)
membrane proteins
intracellular molecules
this type of ion channel is open at RMP and can be either active or passive
leak chanel
all passive channels are
leak channels
intracellular proteins are predominately
anions
leak channels in the plasma membrane allow _____ and _____ movement across the membrane
K+ and Cl-
Conductance of _____ is 20 times greater then to Na
K+
Due to unequal conduction potentials, we see ______ distribution of Cl, K and Na across the membrane
unequal
____ is high inside and low outside
K+
____ and ____ are high inside and low outside
Na and Cl
We have both ____ and ______ for Na, Cl and K across the membrane
chemical and electrical potential
Ena =
+55mV
Ek =
-75 mV
Ecl=
-69mV
Some of the leak is opposed by the NaK ATPase pump that moves _____ions out of the cell and ____ions into the cel
Na
K
ion channels for a ______ channel in the center
hydrophyilic
is the membrane potential at which an ion is in electrochemical equilibrium across membrane
Nerst potential
