Basic Excitability Flashcards
(28 cards)
what are cell membranes made up of?
phosphoglycerides
what type of barrier does a cell membrane form?
hydrophobic
what does a hydrophobic barrier do?
doesn’t let water of hydrophilic molecules through
what in the cell membrane determines where hydrophilic molecules go?
proteins
with the help of active transporter proteins…
cells maintain a trans-membrane ion concentration gradient
give an example of an active transporter protein
Na+ K+ - ATP pump
what is the charge inside a cell at rest
-60mV to -70mV
how are electrostatic forces in a cell generated
charged ions are either repelled or attracted by the Vm
what determines the movement of ions
sum of electrostatic force and the chemical diffusion force
at ENa:
electrostatic force on Na+ ions is equal but opposite to the chemical diffusion force on Na+ ions
the driving force on an ion:
Vion(Vm-Eion)
Eion means …
equilibrium potential for an ion
for cell membranes and ions Vm=
Iions x Rions
what is meant by Pion
ion conductance or permeability
in neurons …. are fixed but …. is variable
ion concentration … Pion
what is a voltage-gated channel?
a protein that forms a pore
when to voltage-gated channels open
with depolarisation, +vely charged amino acids move into the electrostatic field
Na+ and k+ channels are …
voltage gated
voltage- gated channels are an example of…
positive feedback
how are voltage-gated channels an example of positive feedback?
because as Vm increases the chance of a channel to be open increases which increases the Vm further
what are the two voltage-gated channel gates called?
activation gate and inactivation gate
the activation gate Is the …
front door
the inactivation gate is…
the back door
the activation gate for Na+…
opens quickly with depolarisation
