Membrane physiology

This PPT is uploaded by Prof.Dr.R.R.Deshpande.This is prepared by Prof.Dr.A.R.Joshi ,Physilogist on Membrane Physiology

1. Membrane Physiology
Dr. A. R. Joshi
Professor of Physiology,
Bharati Vidyapeeth Medical College,
Pune.

2. Structure of cell

3. Unit Membrane
(Fluid Mosaic Model)
•Ingredients: 1. Phospholipids & Cholesterol
2. Lipoproteins
3. Glycocalyx

4. Cell Membrane

5. Cell Membrane

6. Types of Channels
● Ligand gated channels
e.g. Na+ channels at N-M Junction
● Voltage gated channels
e.g. Ca++ channels on nerve membrane

7. Functions of cell membrane
•Protection
•Electrical property
•Transports across membrane
(Semipermeable )
•Cell to cell communication
•Movement and phagocytosis

8. Transports across cell membrane
Passive transports :
●Diffusion:
- Simple diffusion
- Facilitated diffusion
- Diffusion thro’ channels

●Osmosis

9. Transports across cell membrane…
● Active transports
–Uniport
–Symport (co-transport)
–Antiport (counter-transport)

● Endocytosis & Exocytosis

10. Simple diffusion

11. Facilitated diffusion

12. Diffusion thro’ channel

13. Osmosis

14. Summary of ionic transport

15. Active Transport - Glucose

16. Active Transport – Na-K pump

17. Endocytosis & Exocytosis

18. Ionic Concentration ECF ICF
Na
+
142 mEq/l 10 mEq/l
K
+
3 to 5 mEq/l 140 mEq/l
Cl
-
103 mEq/l 4 mEq/l
HCO3
-
28 mEq/l 10 mEq/l
Ca
++
2.4 mEq/l 0.0001 mEq/l
Mg
++
1.2 mEq/l 58 mEq/l
PO4
---
4 mEq/l 75 mEq/l
SO4
--
1 mEq/l 2 mEq/l
Proteins 2 gm/dl (5mEq/l ) 16gm/dl (40 mEq/l )
pH 7.4 7

19. Resting Membrane Potential
•The difference in electric potential that
exists across the cell membrane when cell is
in resting state
•Developed due to K ions (-94mV)
Na ions (+ 8mV)
Na-K pump (- 4mV)

20. Measurement of RMP

21. Resting Membrane Potential
•Nernst’s equation:
RMP= +61 log ﴾Conc. of ions inside﴿

﴾Conc. of ions outside
﴿
(Corrected by Goldman’s equation)
•RMP -Skeletal muscle –90mV
-Nerve fiber –90 mV
-Heart SA node –55mV
-Heart muscle fiber –90 mV
-Hair cells in inner ear – 150mV

22. Action potential
•Series of events occurring in RMP when
cell is stimulated with adequate stimulus
•Events 1. Application of adequate stimulus
2. Depolarization (Na
+
influx)
3. Repolarization (K
+
efflux)
4. Hyperpolarization
5. Na+-K+ pump

24. Action Potential-Cardiac Muscle

25. Properties of action potential
•Propagation
(Impulse- self propagatory A.P.)
•All or none law
•Refractory period
(Short R.P. for skeletal muscle and nerve
Long R.P. for cardiac muscle)

26. Auto-rhythmicity by S.A. Node
(Leaky sodium channels)

27. Cell to cell communication
•Mediators
–Neurotransmitter
–Local hormone
(either excitatory or inhibitory)
e.g. Neuromuscular transmission
Synaptic transmission

30. Neuromuscular junction

31. Drugs acting at Neuro-muscular Junction
● Cholinomimatic drugs- e.g. Pilocarpine
● Anti-cholinergic drugs-e.g.Atropine
● Competitive inhibitors- e.g. Scholine

● Anticholinesterases -e.g.Neostigmine

● Drugs regenerating cholinesterase- e.g.PAM

32. For Assistance in Physiology
•Dr. A.R. Joshi
Professor of Physiology
(mobile : [phone])
email:
[email protected]