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Bio signals

Bio signals. Eugen Kvasnak, PhD. Department of Medical Biophysics and Informatics 3rd Medical Faculty of Charles University. Cell membrane and resting potential electro-chemical activity and equilibrium, permeability , active a passive transport, channels , osmosis Excitable cell

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Bio signals

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  1. Biosignals Eugen Kvasnak, PhD. Department of Medical Biophysics and Informatics 3rd Medical Faculty of Charles University

  2. Cell membrane and resting potential electro-chemical activity and equilibrium, permeability,active a passive transport, channels, osmosis Excitable cell neuron: properties, action potential, signal integration, muscle cell Nervous a muscle excitable tissue ElectroEncefaloGraphy, ElectroCardioGraphy, ElectroMyoGraphy, ElectroRetinoGraphy, ElectroOculoGraphy, ElectroHysteroGraphy, ElectroGasteroGraphy, MagnetoEncefaloGraphy Another types biosignals synaptic potentials, unit activity, population response, evoked potentials

  3. Cell membrane

  4. Na-K pump Vm

  5. Membrane Current im membran current im t time / ms distance / mm

  6. Cytoplasmic membrane (orplasmalema) • Function: • selective transport between cell and vicinity • contact and mediation of information between cell and vicinity • Structure: • thin semi-permeable cover surrounding the cell • consists from one lipid double-layer and proteins anchored in there • lipid double-layer… gives basic physical features to plasmalema • … on / in: floating or anchored proteins (ion channels) • proteins … anchored in lipid double-layer in different ways • … give biological activity and specificity to plasmalema • glykokalyx… protective cover of some cells formed of oligosacharides, … there are receptors, glykoproteins and other proteoglikans • … protects against chemical and mechanical damage

  7. Material transport across the cytoplasmic membrane • Pasive transport • Difusion • -free transport of small non-polar molecules across membrane • Membrane channel • - transmembrane protein • transport is possible without additional energy • cell can regulate whether it is open or not (deactivated) • channel is specific for particular molecule • Osmosis • solvent molecules go through semipermeable membrane from low concentration site to the higher concentration site  development of chemical potential • Aktivní transport • cell has to do a work (in form of chemical energy, mostly ATP) for transportation • it’s done by pumps, plasmatic membraneprotein anchored in both lipid layers (e.g. Na+-K+-ATPase) • result of ion transport different ion concentration in/out cellelectric potential • ‘Macro’ transport • endocytosis& exocytosis

  8. Action Potential = ALL x NOTHING

  9. Action Potential

  10. Action Potential = opening of sodium and potassium channels

  11. Action Potential excitable cell Vm Na+ -channels K+ -channels time resting potential

  12. equivalent Current Dipole

  13. Active and Passive Transport   chemical (concentration) + electric gradient  electro-chemical potential on membrane !!! Cell INSIDEis NEGATIVE compare to OUTSIDE (in rest usually –75mV)

  14. Excitable cell: NEURON • structure: • dendrites with synapses • body • axon with myelin and synapses • function: • thresholding of input signals • integration (temporal and spacial) of input signals • generation of action potentials

  15. Synapse

  16. Synapse

  17. HOW to measure potentials ? • by electrodes - intracellular, • - extracellular, • - superficial • indirectly – by recording of charge spread ... probes (e.g. fluorescence) • FROM WHERE to measure potentials? • - from whole body, organ, tissue slices, tissue culture, isolated cell

  18. Types of biosignals • Synaptic potentials – excitatory pre- / post-synaptic potentials, inhibitory pre- / post-postsynaptic potentials mostly they don’t cause AP because of weaktime and spacial summations (correlation) … they don’t reach threshold for AP • Unit activity – activity of one neuron, ACTION POTENTIALS • Population response – summary response of neuronal population • APs of thousands of neurons • Evoked potentials – response of sensory pathway to the stimulus

  19. Synapticpotentials EPSPaIPSP

  20. Synapticpotentials

  21. Unit activityvs. Population response

  22. Evoked potentials • … averaged signal of many cells • … recorded from: • Cerebral cortex • Brainstem • Spinal cord • Peripheral nerves • …

  23. Excitablecell: NEURON and MUSCLE CELL

  24. Striated muscles • skeletal muscle – controlled by CNS via moto-neurons • heart muscle - not controlled by CNS • - refractory phase is longer than contraction (systolic) a relaxation (diastolic) time • Smooth muscles – not controlled by CNS, but by autonomic system

  25. Heart

  26. Heart Atrial systole Ventricular systole

  27. Heart cardiac dipol added up the local dipols:

  28. Heart cardiac cycle

  29. Heart cardiac vector field in transverse plane M

  30. Heart cardiac vector field j =const

  31. Heart ElectroCardioGram Change of electric potential  heart muscle activation atriumdepolarization 3 diff. recording schemes: Einthoven, Goldberger, Wilson Frequency = 1-2 Hz !

  32. Heart 2-dimensional recording

  33. Heart Eindhoven’s triangle

  34. Brain ElectroEncefaloGram • Waves: • Delta: < 4 Hz ... sleeping, in awakenesspathological • Theta: 4.5 -8 Hz ... drowsiness in children, pathologicalin aduls • (hyperventilation,hypnosis, ...) • Alfa: 8.5 -12 Hz ...relaxationphysical / mental • Beta: 12 - 30 Hz ... wakefulness, activeconcentration • Gama: 30–80 Hz …higher mental activityincluding perception and consciousness

  35. Biosignals Recording: ElectroMyoGraphy – electric activity of skeletal muscles ElectroRetinoGraphy – electric activity of retina ElectroOculoGraphy – electric activity of eye movements ElectroHysteroGraphy– electric activity of hystera (uterus) ElectroGasteroGraphy – electric activityof stomach MagnetoEncephaloGraphy– electric activity of brain ...

  36. Other Biopotentials? Other Signal Sources? • ECG • EEG • EMG • EGG • ERG • … • Temperature • Motion • pH • pO2 • Chemicals • …

  37. Thanks for pictures: R. Hinz, Summer School + other free web sites

  38. Thank you for your attention!

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