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Flashcards in neurophysiology Deck (18)
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1
Q

what are the 2 fundamental discoveries that allowed the elucidation of basic neural function?

A
  1. microelectrode

2. squid giant axon

2
Q

what does a giant axon do?

A

.the bigger the axon the faster electricity is conducted

3
Q

what is a nervous signal?

A

.nervous signal is a change in resting potential

4
Q

what is neuron resting potential?

A

.neuron has a negative resting potential (-60mV)

. inside neuron is negative charge

5
Q

what happens when two electrodes rest on surface of axon?

A

. no potential difference

6
Q

what are the two ways resting membrane potential can change?

A

. hyperpolarisation- more negative neuron

.depolarisation - less negative neuron

7
Q

what is the ionic composition of a resting neuron?

A

. inside neuron we have k+ and A-

. outside neuron we have Na+ and Cl-

8
Q

what are the two types of force that can act on an ion?

A
  1. chemical force - ion will move from area of high concentration to low concentration
  2. electrostatic force - an ion will be attracted to the opposite polarity
9
Q

what happens to Na+ in a neuron?

A

.sodium is positive and inside the neuron is negative
.Na+ has strong tendency to move inside the negative neuron
.both electrostatic and chemical forces tend to push sodium into the cell

10
Q

what happens to K+ in a neuron?

A

.K+ has lower tendency to get out of neuron

11
Q

what forces act on K+?

A

. 2 opposing forces act on K+ in a resting neuron.
. electrostatic force holds K+ within the cell
. chemical force pushes K+ outside cell
. chemical force is stronger than electrostatic
. there is a weak net resultant force pushing K+ out cell

12
Q

what are the 2 factors that will determine the movement of an ion across a membrane?

A

. size of the electrochemical gradient

. permeability of the membrane

13
Q

why is the resting potential of a neuron negative?

A

. membrane is only permeable to K+
. k+ will leave the neuron
. this will lead to a build up of positive charge outside the neuron which will begin to oppose exit of K+
.eventually an eq is set up when chemical force pushing K+ out cell is equalled by electrostatic force holding it in

14
Q

when is an eq reached?

A

. this occurs when the inside of neuron is -75mv which is resting potential of most neurons

15
Q

how is the leakage of Na+ stopped in resting neuron?

A

sodium/potassium pump

16
Q

what is a sodium/potassium pump?

A

an enzyme that spans the membrane

17
Q

what is the function of sodium/potassium pump?

A

for every 3 sodium ions removed from the cell , 2 potassium ions are pumped in

18
Q

What happens when equilibrium is established?

A

when the chemical force is exactly balanced by the electrical force.