L7: Neurons & Neuron Communication I Flashcards
How are electrical potentials measured?
1) Extracellular Recording
2) Intracellular Recording
3) Patch Clamping
1) Electrode outside cell
2) Electrode inside cell
3) Electrode sealed to cell surface
At rest, is the inside of the membrane more negative/postive than the outside?
More negatively charged (hyperpolarised)
1. Specialised pumps
- Relatively impermeable
- Separate & store ionic
3 reasons how the electrochemical gradient across a membrane is established
1) Specialised pumps move ions against conc grad
2) Membrane relatively impermeable, movement of ions restricted to specialised channels
3) Membranes separate & store ionic charge between inside & outside the cell
Features of the resting membrane potential
Around -70mV
Determined by Na+ & K+ ions
Inside cell is negative, K+ prevented
Inside cell is postivie, Na+ prevented
What does the amount of work done at the membrane depend on?
Size of the concentration gradient
Equation for conc grad for +ve ions
(C) out / (C) in
Equation for conc grad for -ve ions
(C) in / (C) out
Nernst Equation
E = 58 (mV) x log (C) out / (C) in
What mV do cells need to be to stop K+ leaving & stop Na+ leaving ?
K+ : -90mV
Na+ : +50mV
Is Vm closer to EK or ENa?
EK, because membrane has more K+ channels and is more permeable
Action of Na+ into the cell
Resulting in depolarisation (more +)
Action of K+ out of the cell
Resulting in repolarisation (more -)
What sets the membrane potential?
Specific ionic distribution across the membrane
Two forces ions are under
1) Electrostatic force (dependent on charge)
2) Force of diffusion (dependent on conc)
3 functional states of ion channels
1) Closed (resting)
2) Open (active)
3) Inactive (refractory
