Work

• Electricity


  The flow of electrons between atoms
• Human bodies


  • Huge masses of atoms
  • Can generate electricity
• Nervous system signals


  Electricity carrying messages between point A and point B
• Electrotonus


  The flow of direct current through nerve and muscle tissue causing a change in their excitability
• Electrotonus


  1. Displacement of ions

  2. Changes in the polarization of cell membranes

  3. Occurring during the flow of current
• During the flow of direct current

  Excitability increases under the cathode, and decreases under the anode
• Catelectrotonus


  The state of increased excitability occurring under the cathode
• Anelektrotonus


  The state of reduced excitability under the anode
• Changes in the excitability of nerve tissue under the influence of direct current

  • Play an important role in electro-treatment procedures
• Potassium and sodium ions carry a positive charge
• When a cell isn't transmitting electrical signals, there will be a higher concentration of sodium ions outside the cell than inside the cell
• There will also be more potassium ions inside the cell than outside it
• The space surrounding the cell is going to have a charge that's relatively more positive than the space within the cell
• The charge inside this cell will be negative by comparison
• Resting membrane potential (RMP)


  The state where the charge inside the cell is negative compared to the outside
• Electrochemical gradient


  The charge difference on each side of the cell's membrane
• Ion channels


  Channels located in the membrane that grant passage to specific kinds of ions
• Voltage-gated ion channels


  Pathways that only open up and allow the transfer of ions when the cell's membrane potential has shifted by just the right amount
• Neurons contain both sodium voltage-gated ion channels and potassium voltage-gated ion channels in their membranes
• Action potential


  A rapid sequence of changes in the voltage across a membrane
• Action potential


  1. Depolarization

  2. Repolarization
• At RMP, there will be more sodium ions outside these cells than there are inside them
• Action potential


  1. Sodium ions pouring into the cell

  2. Depolarization
• The rapid increase of sodium ions makes the inside of the cell more positively charged than the space surrounding it, which is the exact opposite of the situation at RMP
• Action potential


  A wave of electrical discharge that travels along the membrane of a cell
• Action potentials can be created by many types of cells, but are used most extensively by the nervous system for communication between neurons and to transmit information from neurons to other body tissues such as muscles and glands
• Resting membrane potential


  Takes into account equilibrium potentials of all ions
• Normal cell resting membrane potential = -70mV (interior of cell is negatively charged with respect to exterior)
• Depolarization


  The loss of the normal negative value of the resting membrane potential
• Repolarization


  The return of a cell's membrane potential to resting potential after depolarization
• Hyperpolarization


  The change in the membrane potential towards a more negative value
• Repolarization


  1. Sodium-potassium pumps ejecting sodium ions and pulling in potassium ones

  2. Reinstating RMP by making the inside of the neuron more negatively charged than the outside
• The human body, at rest, can produce around 100 watts of power on average
• Some humans can output over 2,000 watts of power when sprinting
• Electric shock sensations


  Mostly associated with Lhermitte's sign
• Lhermitte's sign occurs because the immune system attacks the nerve fibers and destroys myelin, which slows down signals that travel between nerves
• Voltages above 50 volts


  Dangerous, but it's not the voltage that kills but the current and the amount of time you're exposed to the voltage
• Anything higher than 300mA is fatal and kills in seconds
• 4.5 to 10A will instantly lead to cardiac arrest, severe burns and finally death
• Electric power


  A mixture of current and voltage, where voltage (as a pressure) pushes electric current (as a flow of charge) is responsible for electric shock