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سیناپس

سیناپس. الف) سیناپس الکتریکی ب) سیناپس شیمیایی. 2. 2. Types of cell-cell junctions: Tight junctions membranes fused Gap junctions close juxtaposition (2-4 nm) electrical synapse Chemical synapses synaptic cleft (20-30 nm) polarized. Electrical Synapse (rare).

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سیناپس

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  1. سیناپس الف) سیناپس الکتریکی ب) سیناپس شیمیایی 2 2

  2. Types of cell-cell junctions: Tight junctions membranes fused Gap junctions close juxtaposition (2-4 nm) electrical synapse Chemical synapses synaptic cleft (20-30 nm) polarized

  3. Electrical Synapse (rare)

  4. Transmission of an Action Potential across an Electrical Synapse and a chemical synapse Most of the synaptic delay (1-2 mSec) is due to the time it takes to organize the presynaptic processes

  5. 7 7

  6. 8 8

  7. Release of synaptic vesicles

  8. 11 تاخیر سیناپسی: زمان مورد نیاز برای عبور پیام از شکاف سیناپسی / نیم تا یک میلی ثانیه تاخیر هسته ای: زمان مورد نیاز برای جمع پذیری فضایی و زمانی تحریکات وارده بردندریتها و جسم سلولی نورون است که طی آن پتانسیل غشای نورون پس سیناپسی ممکن است تا آستانه تحریک دپلاریزه شود./ حدود دو میلی ثانیه 11

  9. 12 12

  10. 13 13

  11. 14 14

  12. 15 15

  13. انواع سيناپسشیمیایی 16 16

  14. CNS Synapses – types of connections (1) Axosomatic Axoaxonic Axodendritic

  15. CNS Synapses – types of connections (2) 19 19

  16. محل سیناپسها در نورون پس سیناپسی 20 1- قشر مغز: 98 درصد بر روی دندریتها / • 2 درصد بر روی جسم سلولی 2- نخاع: 75 درصد بر روی دندریتها / • 25 درصد بر روی جسم سلولی 20

  17. 21 21

  18. Receptors • neurotransmitter specific postsynaptic receptors • open to allow ions to flow into the postsynaptic neuron • two main types • ionotropic • metabotropic

  19. An example of a ligand gated ion channel The nicotinic Ach receptor. It needs two molecules of Ach in order to open. It is permeable to cations. It is found in the NMJ, autonomic ganglia, hippocampus, thalamus, etc.

  20. Ionotropic Ach receptor

  21. انواع كانال 25 25

  22. 26 26

  23. 27 27

  24. 28 28

  25. 29 29

  26. 30 30

  27. 31 31

  28. Receptors 32 32

  29. Action PotentialandEPSP & IPSP 33 33

  30. 34

  31. 35 35

  32. 36 36

  33. 37 37

  34. Postsynaptic Potential IPSP EPSP Resting Potential Time 38 38

  35. Summation 39 39

  36. III. Neural Integration Convergence

  37. Summation (spatial & temporal) Convergence of input as a factor in Summation

  38. Summation 42 42

  39. Temporal Summation From the Same Synapse Occur when AP arriving from a presynaptic axon terminal of neuron A occur close enough together in time such that EPSPs produced in response to the binding of neurotransmitter overlap and sum.

  40. EPSPs Graded in magnitude Have no threshold Cause depolarization Summate Have no refractory period

  41. Spatial Summation SIMULTANEOUS INPUT FROM TWO SYNAPSES: ABOVE THRESHOLD Threshold Time 45 45

  42. EPSP-IPSP Cancellation 46 46

  43. مهار و تسهیل پیش سیناپسی 47 47

  44. ميانجيهای عصبی Neurotransmitters

  45. Neurotransmitters Neurotransmitters are released into the synapse and bind with receptors on the postsynaptic cell membrane, which cause ion channels to open in the new cell.

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