Potentials Flashcards

1
Q

Membrane potential

A
  • the difference in electrical charge inside and outside of a cell
  • (-)70 mV is a neurons resting potential
  • potential inside a resting neuron is less than outside
  • measured with electron inside and outside of a cell
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2
Q

Ionic basis of resting potential

A

ions: positively and negatively charged particles
- sodium and potassium carry a single positive charge
- in resting state more Na+ outside, more K+ inside
- pressure for Na+ ions to enter the cell bc of electrostatic pressure and movement down the concentration gradient
- sodium ions are closed in resting potential preventing Na+ ions to enter
_ potassium channels are open but K+ stay inside because of the negative membrane potential

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3
Q

Postsynaptic potential

A
  • neurotransmitters are released from neurons when they fire and bind to receptors and depolarise or hyperpolarise the membrane of the postsynaptic neuron
    excitatory postsynaptic potential: depolarisations that increase the increase the likelihood that a neuron will fire
    inhibitory postsynaptic potential: hyperpolarizations that decrees the likelihood that a neuron will fire
    balance between EPSP and IPSP determine if a neuron will fire
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4
Q

Action potential

A
  • massive reversal of the membrane potential that lasts 1ms
  • AP are generated if the EPSP and IPSP at the axon initial segment are enough to depolarise the membrane potential to the threshold of excitation (-65mV)
  • if membrane is depolarised, sodium channels open, na+ ions rush in.
  • potassium channels open to counter this
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5
Q

Refractory periods

A
  • after an AP it is impossible for another to occur in 1-2 ms (absolute refractory period)
  • make the AP travel in one direction along the axon
  • increase the rate of firing in reponse to intensity of stimulation
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6
Q

Conduction of Action potentials

A
  • in myelinated neurons the AP is conducted passively along the myelin segments
  • increases the speed at which the AP is travelling
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