1. صدق الله العظيم الاسراء اية 58

2. By Dr. Abdel Aziz M. Hussein Lecturer of Medical Physiology Member of American Society of Physiology

3. Test Yourself which of the following compartments, Na+ ions have the lowest concentration? a)Interstitial fluid. b)Plasma. c)Intracellular fluid. d)Lymph. 3 Biophysics, Abdelaziz Hussein

4. Test Yourself Which mechanism is the main regulator of water intake? a)Changes in ECF PH. b)Urine formation. c)Small changes in ECF volume. d)Thirst. 4 Biophysics, Abdelaziz Hussein

5. Test Yourself Cell membrane : a)Consists almostly of protein. b)Consists almostly of fat. c)Is non selectively permeable membrane d)None of the above. 5 Biophysics, Abdelaziz Hussein

6. Test Yourself The gap junction : a) are absent in cardiac muscle. b)are present but of little functional importance in cardiac muscle. c)are absent in smooth muscle. d)none of the above is might. 6 Biophysics, Abdelaziz Hussein

7. 7

8. 8 Transport Through Cell Membrane Diffusion Active transport Vesicular transport

9. 9 Biophysics, Abdelaziz Hussein Low concentration High concentration

10. 10 Biophysics, Abdelaziz Hussein Def. It is movement of substances across the cell membrane down its electrochemical gradient.

11. 11 Biophysics, Abdelaziz Hussein Low concentration High concentration ATP

12. 12 Biophysics, Abdelaziz Hussein Def. It is movement of substances across the cell membrane against its electrochemical gradient.

13. 13 Biophysics, Abdelaziz Hussein Def. It is the process by which large sized substances are engulfed by the cell membrane to be either;  Pushed inside the cell (endocytosis) or  Pushed outside the cell (exocytosis)

14. 14

15. 15

16. 16

17. 17 Biophysics, Abdelaziz Hussein It is movement of substances across the cell membrane down its electrochemical gradient due to the continuous random motion of its particles

18. 18 Biophysics, Abdelaziz Hussein Low concentration High concentration

19. 19 Biophysics, Abdelaziz Hussein It is divided into 3 subtypes: 1.Simple diffusion. 2.Facilitated diffusion. 3.Osmosis (water only)

20. 20 Biophysics, Abdelaziz Hussein Def It is movement of substances across the cell membrane down its electrochemical gradient by simple movement without the necessity of binding with carrier proteins Mechanisms: It occurs either through; a.Interstices of the lipid bilayer. b.Watery proteins channels.

21. 21 Lipid Interstitices Protein Channels

22. 22

23. 23 Biophysics, Abdelaziz Hussein Characters: It is characterized by; a)Occurs down an electro- chemical gradient b)Passive i.e. no external energy is required.

24. 24 Biophysics, Abdelaziz Hussein Characters: c) It is not rate-limiting i.e. linear with concentration gradients. d) The diffusion process is not saturable.

25. 25 Biophysics, Abdelaziz Hussein

26. 26 Biophysics, Abdelaziz Hussein Mechanism: Lipid soluble substance comes in contact with the membrane at one side and dissolved in the lipid matrix and transported to the other side Rate of diffusion: Its rate of diffusion is determined mainly by its lipid solubility Example : O2, nitrogen, CO2 diffusion

27. 27

28. 28 Biophysics, Abdelaziz Hussein Water diffuses through lipid bilayer of the membrane at high rate like bullets due to; a.Small size. b.Very high kinetic energy

29. 29 Biophysics, Abdelaziz Hussein Urea diffusion Is about 1000 times less than that of water Its diameter is only 20% greater than that of H2O Glucose Is about 10,000 times less than that of water Its diameter is only 3 times that of H2O) Na and K ions diffusion: Is about one million times less rapidly than does water So, their transport must occur through protein channels

30. 30

31. 31 Protein Channels

32. 32

33. 33 Biophysics, Abdelaziz Hussein Protein channels are watery pathways through the interstices of the protein molecules These channels are characterized by 1) Selective permeability 2) Gating of protein channels

34. 34 Biophysics, Abdelaziz Hussein Most, but not all, protein channels are highly selective for the transport of one or more specific ions or molecules 1. Its diameter 2. Its shape

35. 35 Biophysics, Abdelaziz Hussein 3. Nature of the electrical charges of its inside surfaces +ve charged channels +ve charged channels for the passage of –ve charged particles. -ve charged channels -ve charged channels for the passage of +ve charged particles Example: a.Na channels for Na b.K channels for K

36. Biophysics, Abdelaziz Hussein Many of the protein channels can be opened or closed by gates: Structure of gates The gates are extensions of the transport protein molecules close over the opening of the channel Produce conformational change in the shape of protein molecule 36

37. AS Biology, Cell membranes and Transport 37

38. Biophysics, Abdelaziz Hussein Have 2 gates a.Outer m gate b.Inner h gate -Both m and h gate must be open for Na to flow through the Na channels 38

39. Biophysics, Abdelaziz Hussein -When m gate is open → the channel is activated and Na ions can pass through it -When h gate is closed→ the channel is inactivated. 39

40. Biophysics, Abdelaziz Hussein Has one gate on the extracellular side (n gate). n gate must be open for K + to flow through the K + channel 40

41. THANKS