1. Membrane Potential Transduction of signals at the cellular level
Resting Membrane Potential
Action Potential

2. Why do we need to know about RMP and AP?

3. Transduction of signals at the cellular level
EPSP
IPSP
Initial segment AP
Ca2+ influx
Neurotransmitter
Neurotransmitter releasing

4. Somatodendritic part – passive conduction of the signal, with decrement

5. Axon – the signal is carried without decrement

6. Preliminary knowledge
What is necessary to know beforehand

7. Cell membrane Phospholipid bilayer Proteins peripheral
integral non penetrating
penetrating (transmembrane)

11. Na+- K+ pump

12. Extrude 3 Na+ ions Bring in 2 K+ ions
Na+- K+ pump
Extrude 3 Na+ ions
Bring in 2 K+ ions
Unequal distribution of ions
Na+ and Cl - extracelullary
K+ a A- intracelullary

13. Ion channels in the cell membrane
Resting channels - normally open
Gated channels - closed when the membrane is at rest
opening is regulated by
1. Membrane potential (voltage gated)
2. (chemicaly gated)
3. Membrane potential plus ligand binding (Voltage and chemicaly gated)
4. Membrane stretch (mechanicaly gated)

14. voltage gated sodium channel

15. Resting membrane potential

16. Membrane potential is not a potential
Membrane potential is not a potential. It is a difference of two potentials so it is a Voltage, in fact.

17. The unequal distribution of ions
Na+, Cl- are more concentrated outside the cell
K+ , A- are more concentrated inside the cell

18. When the membrane would be permeable for K+ only
Chemical driving force
outward movement of K+ K+
Na+ A-
Cl-

19. When the membrane would be permeable for K+ only
More positiv charges are outside
A- can not leave the cell
electrical driving force emerges
inward movement of K+

20. When the membrane would be permeable for K+ only
Chemical driving force
electrical driving force
electrode can record a voltage
=RESTING MEMBRANE POTENTIAL

21. Equilibrium potential for K+ and Na+
When the membrane would be permeable for K+ only

22. Ion distribution in the nerve fiber
The voltage can be discharged into surroundings

23. How to calculate the magnitude of the membrane potential
Osmotic work
The work, which must be done to move 1 mol of the substance from concentration C1to concentration C2
Ao= R.T.ln [C1] /[C2 ]
Electric work
The work, which must be done to move 1 mol of the substance across the potential difference E
Ae = E. n. F
R.T.ln [C1] /[C2 ] = E. n. F
E =

24. How to calculate the magnitude of the membrane potential
Ao= Ae
R.T.ln [C1] /[C2 ] = E. n. F
E =
Nernst equation

25. Goldman equation

27. Action potential

28. Membrane potential
Conductance of the membrane for Na+ and K+

29. Time segment when the AP cannot be elicited