Neuronal signalling 3 Flashcards
How do ions move across an ion channel?
Facilitated diffusion
What does facilitated diffusion rely on?
Differences in conc of ion on either side of the membrane
What are polygamous ion channels?
Ones that can allow multiple diff ions through
Selective ion channels?
Channels that only allow one ion through
General movement of sodium when a Na+ channel opens?
Sodium usually moves in as there is a lower conc in the cell
General movement of potassium when a K+ channel opens?
Potassium usually moves out as there is a higher conc in the cell
2 diff types of channel?
Electrically gated, chemically gated
When do electrically gated ion channels open?
When the membrane potential reaches a certain point
When do chemically gated channels open?
Upon binding of a ligand (NT)
Role of Na+ channels?
Make membrane potential more +ve
Depolarisation
Role of K+ channels?
Make membrane potential more -ve
Hyperpolarisation
What does the nernst equation determine?
The charge on the membrane that means that an ion can no longer cross, even if its channel is open
What is the Nernst equation for?
Calculating the charge on the membrane when you have the movement of one single ion across it
Why does the nernst equation generate an unrealistic value?
Aren’t dealing w/ only one ion–> Na+, K+, CL-
What is the reversal potential?
The point at which the membrane potential stops changing when you open channels at any specific time
What can the goldman equation determine?
The membrane/reversal potential when multiple channels are opened
What does the Goldman equation take into account that the nernst equation doesnt?
The permeability of all three main ions
Different neuronal potentials?
Resting potential, repolarization potential, depolarization potential
What can cause depolarization?
Graded potentials, APs, inhibitory graded potentials
What is hyperpolarisation?
Potential drops below its resting state
General resting potential?
-40 to -90 mV
How is the threshold reached?
Opening of VG channels, causing graded potentials
What two things can graded potentials be?
Excitatory or inhibitor
What happens to the membrane potential as a result of Na+ channels opening?
It increases
What happens to the membrane as a result of Cl- channels opening?
it decreases
