resting membrane potential hafiz m waseem

1. Topic Name :
Resting Membrane
Potential
Submitted by :
Hafiz Muhammad Waseem
Roll No. mcf-1901171
Class : MSc Zoology
Submitted to :
Mam Razia Bashir
Submitted Date : 16-01-2

2. Contents
 Introduction
 History
 Define RMP
 Measurement RMP
 Ion gated channels
 Movement of ion
 Sodium potassium ATPase Pump
 Conduction velocities vary widely among neuron
 Salutatory conduction
 References

3. History
 Resting current in nerve were measure and
describe by Julius Bernsteinin 1902
 He proposed a ‘ A Membrane Theory ’’
 that explain the resting potential of nerve
and muscle as diffusion potential

4. Introduction of neuron
a) dendrites - input
b) cell body – “decision making”; graded
potential
c) axon - transmits action potential

5. Define
 The difference in charge with more positive out
side and more negative ions inside
 A resting neuron is not conducting a nerve
impels
 Fluid inside PM –vet outside PM +vet charge
 All cells have a resting potential
 But neuron and muscle cells are specialized
transmit and resting potential rapidly

6. dendrite
axon
Cell
body

7. Axon form connection with muscle or
dendrites with other neuron

8. Component present outside and inside
neuron

9. Membrane outside more positive inner
side more negative at resting potential

10.  The potential difference (–70 mV) across the
membrane of a resting neuron
 It is generated by different concentrations of
Na+, K+, Cal, and protein anions (A)
 The cytoplam inside a cell is negative and the
outside of the cell is positive. (Polarized)

12. Types of membrane channels
 (1) Leak (Diffusion , Passive ) channels : - Pores in the
cell-membrane which are open all the time , therefore
ions diffuse through them according to the ion
Concentration Gradient .
 (2) Voltage-gated channels :
 open when the cell-membrane is electrically activated .
 (3) Chemically-gated ( ligand-gated ) channels : open by
chemical neurotransmitters at neuromuscular junctions
& synapses )connections b/w neurons).

13.  Chemically gated channels –
open with binding of a specific
neurotransmitter
 Voltage-gated channels – open
and close in response to
membrane potential (change
in charge)
 Mechanically gated channels –
open and close in response to
physical deformation of
receptors

14. Chemically gated channels

15. Voltage gated channels

16. Closed Mechanically gated channels

17. Open mechanically gated channels when
pressure apply

18. Release Neurotransmitters
acetylcholine Norepinephrine

19. Ion channels
 They are present in PM.
 Sodium potassium ions constantly
diffuse through these ion
channels
 Cal ion and negative protein ion
also present.
 They have large in size .
 They cannot pass through in this
channels.

20. Ion gated channels are channels
constantly open

21. Movement of ions
 When gated channels are open:
Ions move along chemical gradients,
diffusion from high concentration to
low concentration. Ions move along
electrical gradients, towards the
opposite charge
Together they are called the
Electrochemical Gradient
 An electrical current and Voltage
changes are created across the
membrane

22. Sodium-potassium ATPase Pump
 It is present in Pm
 It is powered by ATP
 It keep the concentration of sodium and potassium ion constant on two side of
membrane
 it move sodium out side and potassium inside the membrane
 it move 3 sodium outside and 2 potassium inside the membrane
 this pump maintain resting potential across membrane

23. Closed sodium potassium ATPase pump

24. Open sodium potassium ATPase pump

25. Factor that effect that RMP
1. Difference of potassium ion concentration across membrane
2. Due to fact that cell membrane at rest is much more permeable to k ion
than Na ion
3. The movement of K ion has greater influence on the RMP
RMP of cell at rest in this case is -70 mv
4. Permeability of membrane to Na and K
5. Action of Na pump

26. Factor that make inside of the cell
negative
• Depend mainly on transport properties of
resting membrane,
• 1- Contribution of K & Na diffusion potential
through Na & K leak channels of nerve
membrane
• 2- Active transport of Na & K ions ( Na/K
pump)
• 3- Negative ions inside membrane as proteins
& phosphate sulphate

27. Measurement RMP
 Resting potential measure in millivolt is 1/1000 of m volt
 RMP is about -70mv

28. •VOLTMETER
To measure very small membrane
potential difference between inside &
outside as resting membrane potential
. How?
•-A small filled pipette containing
electrolyte solution is inserted inside
the nerve fibber & another electrode
is placed in the outside & membrane
potential difference between inside &
outside is measured using the
voltmeter.
Measuring membrane potential

29. Conduction velocities vary widely among neurons
 Rate of impulse propagation is determined by:
 Axon diameter – the larger the diameter, the faster the
impulse
 Presence of a myelin sheath – myelination dramatically
increases impulse speed

30. Salutatory Conduction
Figure 11.16

31. References
Bennett, Tom, PowerPoint slides, 3/23/05
Jack, Pasternak J. An Introduction to Human
Molecular Genetics. 2nd ed. New Jersey:
Wiley-Liss, 2005.

32. FOR YOUR PATIENCE