Chapter 1: activity 5

• a nerve impulse is an electronegative wave that moves on the surface of a nerve fiber.
• properties of nerve fibers:

  1. excitability
  2. conductility
• types of excitation:

  • thermal
  • electrical
  • chemical
  • mechanical
• the threshold of excitation is the minimum effective intensity below which there is no response. such an intensity is known as intensity rheobase (Irh)
• Rest potential refers to the state of a potential difference that exists between the intra-cellular medium and the extra-cellular in such a way that the intra-cellular medium is negatively charged with respect to the extra-cellular medium which is positively charged.

  
  

  in simpler words:

  the rest potential is the state of polarization of a nerve fiber.
• effective stimulation is I>=Irh
• 1. state of polarization
  2. state of depolarization
  3. state of repolarization

  
• law of all or nothing means that the nerve fiber responds to an excitation greater or equal to Irh to the maximum
• law of summation indicates that as we increase the intensity of excitation MORE nerve fibers are going to respond that will ADD to the previous ones
• the max global potential is the maximum response which signifies the response of all nerve fibers.