![5. CONDUCTION
TYPE
1.LAW OF FORWARD CONDUCTION (in vitro both directions, normally
impulse travels in 1 direction only-in the motor nerve towards
the responding organ; in sensory nerve toward the center]
2. LAW OF BELL AND MAGENDIE
3. LAW OF ISOLATED CONDUCTION
4. LAW OF PHYSICAL INTEGERATION
5.LAW OF 2 WAY CONDUCTION](https://image.slidesharecdn.com/physiologyofelectrostimulationinhumanbody-181011042308/85/PHYSIOLOGY-OF-ELECTROSTIMULATION-IN-HUMAN-BODY-BY-DR-QAZI-IMTIAZ-RASOOL-19-320.jpg)
PHYSIOLOGY OF ELECTROSTIMULATION IN HUMAN BODY BY DR QAZI IMTIAZ RASOOL
- 1. PHYSIOLOGY OF ELECTROSTIMULATION IN HUMAN BODY By DR. QAZI IMTIAZ RASOOL
- 2. Each area of axon consists of an electrical circuit axon is represented as a hollow, cylindrical "cable" that is filled with an electrolyte solution
- 4. CABLE PARAMETERS Passive conduction properties LENGTH OR SPACE CONSTANT (Λ) mathematical constant used to quantify the distance that a graded electric potential will travel along a neurite via passive electrical conduction. > length constant, the farther the potential will travel. λ = distance (mm) at which ( lambda) If you have a length constant of 1 mm, that means at 1 mm away from the cell body in an axon, 37% of the voltage magnitude remains. TIME CONSTANT time and current (charge) to charge the membrane capacitor as current drops over the length of the nerve τ is the time it takes to reach 63% of the final voltage (msec) - capacitor, τ=RC. (in seconds) that (it takes a capacitor tocharge to 63% of the voltage that is charging it up.)
- 6. 1. Bathmotropic 2. Dromotropic 3. Chronotropic 4. Lusitropic 5. Inotropic 6. Metabotropic Terminology in excitable cells
- 7. 1.Faradic Galvanic Test 2.Measurement of Rheobase and Chronaxie 3. Strength Duration Curve 4.Nerve Conduction Velocity Studies Diagnosis of electrostimulation
- 10. 1.EXCITIBILITY STIMULUS 1.MECHANICAL 2.CHEMICAL 3.THERMAL 4.ELECTRIC 5.OSMOTIC After excitation, nerve impulse is generated through depolarisation, repolarisation and hyperpolarisation
- 11. Factors that Determine the Excitability/Bathmotropic 1. RMP 2. Threshold potential 3. Concentration of extracellular Ca2+ 4. Strength of stimulus 5. Duration of stimulus 6. The direction of the current 7. Frequency of impulse 8. Nernst Equation Variables
- 12. 2. LATENT PERIOD 1. VELOCITY 2.DIAMETER
- 13. 3. All-or-none law: • -If the stimulus be adequate, a single nerve will always give a maximum response – • If the strength or duration of the stimulus be further increased, no alteration in the response will take place (In the whole nerve this property differ ,but is true for a single nerve).
- 14. 4. Strength-Duration curve 1STRENGTH 2. DURATION CHRONIEXIA RHEOBASE Both are increased in denervated muscle. These values are greatly varies with few variables like temp, blood supply, electrode size and skin resistance.
- 15. RHEOBASE “rheo” = current “base” = foundation is the foundation, or minimum, current (stimulus strength) that will produce a response
- 16. CHRONAXIE “chron” = time “axie” = axis: is measured along the time axis is a Duration that gives a response when the nerve is stimulated at twice the rheobase strength.
- 17. 1. TISSUES OF NEWBORN=10 TIMES LONGER THAN ADULT 2. TISSUES OF COLD BLOODED LONGER THAN IN WARM 3. FLEXOR< EXTENSORS 4. PALE< RED MUSCLE 5. DEGENERATIVE MUSCLES> THAN NORMAL 6. SKELETON <CARDIAC 7. A.NS> S.NS. 8. ADRENERGIC<CHOLENRGIC FIBRES 9. SCT> 3TIMES LONGER THAN VEN;+ATRIAL MUSCLES CHRONAXIE
- 18. Strength duration curve 1. is a graph between electrical stimuli of different intensities 2. S-D curve should be plotted after 20th day of injury/lesion. 3. After 21st /22nd day, regeneration of nerve will start, generally it take about 270 days to regenerate. 4. The purpose of S-D curve plotting is to know whether the stimulated muscle is innervated, denervated or partially denervated. • There are also other method for this purpose like EMG and NCV. Strength Duration
- 19. 5. CONDUCTION TYPE 1.LAW OF FORWARD CONDUCTION (in vitro both directions, normally impulse travels in 1 direction only-in the motor nerve towards the responding organ; in sensory nerve toward the center] 2. LAW OF BELL AND MAGENDIE 3. LAW OF ISOLATED CONDUCTION 4. LAW OF PHYSICAL INTEGERATION 5.LAW OF 2 WAY CONDUCTION
- 20. 5. Factors Affecting Conductivity (Dromotropic) 1.DIAMETER 2. MYLENATED 3.TEMP; 4.MECHANICAL PRESSURE 5. CHEMICAL 6.SPIKE POTENTIAL ^ CONDUCTION INCREASES 7.PH 8. BLOOD SUPPLY O2 9. CHEMICALS; NARCOTICS DIMINISH DRUGS; ANAESTHESIAS 9.EFFECT OF IONS 10.LEVEL OF RMP 13.CAPACITANCE 11.CONSTANT CURRENT
- 21. 6. ELECTROTONIC 1. LOCASL RESPONSE 2.SUB THRESHOLD 3.RECEPTOR- POTENTIAL 4.SYNAPTIC -POTENTIAL
- 23. CHANGES IN NERVES DURING CONDUCTION 1. CHEMICAL=OXYGEN ABSENT LEADS TO ACCUMULATION OF LACTIC ACID,+CHANG DUE TO ACCUMLATION OF CO2( PH ). 2.THERMAL CHANGES= LESS ENERGY NEEDED+HEAT PRODUCTION 3.ELECTRICAL CHANGES= ELECTRIC PROPERTIES 4.PHYSICAL CHANGE- CHANGES IN BIREFRINGERNCE, LIGHT SCATTERING. FLUORESCENCE 5. STRUCTURAL CHANGES= PROTIEN CHANNELS FLOATING IN MEMBRANE
- 24. 8.REFRACTORY PERIOD MAXIMUM FREQUENCY=1000/SEC. 1.Absolute Refractory Period - due to time dependence of Na+ channel • No amount of inward current will generate another AP • Due to the Na+ inactivation gate which is slow to close when triggered at threshold 2.Relative Refractory Period • Need an excess of current to generate an AP because the Na+ channels are still inactivated until the end of repolarization phase
- 25. 9. INFATIGABILITY 1. LONG REFRACTIORY PERIOD 2. CAN CONDUCT ONLY 1 IMPULSE AT A TIME In the nerve muscle preparation, if the nerve is stimulated repeatedly, then after a certain period the muscle fails to give any response but nerve is not fatigued.
- 26. 10. SUMMATION may be inhibitory or excitatory 1. Temporal or Spatial Summation 2. Repetitive Stimulations • FACILITATION the short-term increases in strength is (which lasts tens to hundreds of milliseconds), • AUGMENTATION (lasting several seconds), • POTENTIATION (lasting tens of seconds to several minutes and outlasting the period of high-frequency stimulation). 1. Post-tetanic Potentiation - after repetitive firing, Ca+2 channels are synchronized resulting in a more amplified EPSP following tetanus 2. Synaptic Fatigue - delay in response after synapse following prolonged tetanus (NTs have to be re-packaged)
- 27. 11. ADAPTATION 1. quickly adapts itself. 2. there is no excitation during the passage of a constant current. 3. Only when the strength of the current is suddenly altered or the current is made or broken excitation takes place
- 28. 12. ACCOMODATION If the stimulus, even with stronger strength is applied very slowly to a nerve, these may have no response only due to l of attaining the threshold strength.
- 29. • - secretion of hormones released in response to electrical activity in the neuron. e.g. ADH, oxytocin, releasing hormones -Actually all neurons secrete chemical mediators, but usually into synaptic cleft. Difference is secretions are transported by blood 13. NEUROSECRETION
- 30. 14.NEUROTROPINS promote: development, heath, survival of neurons • BDNF: synaptic plasticity, neuronal survival and differentiation • Nerve growth factors • Nerve growth factor (NGF), • brain-derived neurotrophic factor (BDNF) • , glial-derived neurotrophic factor (GDNF • Studies suggest BDNF disruption in: • Huntington’s • Alzheimer’s • Multiple Sclerosis • Parkinson’s
- 31. Strength-Duration Curve (Excitability Curve) Utilization time (nerve) Chronaxie of nerve Utilization time (muscle) Chronaxie of muscle 2.0 1.5 1.0 .5 0.1 0.2 0.3 Duration of stimulus (seconds)