CHEDS- theme 6- the electrical properties of neurons Flashcards
what organism is used to study membrane potentials? why?
the giant squid because some axons are 0.5- 1mm thick and are unmyelinated (decreases conduction velocity potential substantially).
how is a volt meter used to measure neural potentials?
measures the voltage difference between the inside and outside of the neuron using micro electrodes. this is measured as a function of time.
What is the function of the plasma membrane in the generation of potentials?
The plasma membrane separates charges by keg different either in or out of the cell. the difference in ion concentration between the interior and exterior of the cell act as an electrical force that can be measured in volts.
what is the rating potential of a neuron?
-70mv. the interior Lismore negative than the exterior.
what are 3 membrane factors contributing to sting potential?
- Na+/K+ -ATPase pump
- Ion Channels
- negatively charged molecules.
function of Na+/ K+ -ATPase pump?
transports 3 sodium ions out for every 2 potassium ions in.
more Na+ out of the cell than in.
more K+ in the cell than out.
Ion channels. GO
Voltage-gated Na+ channels
Voltage-gated K+ channels.
Negatively charged molecules and the effect on resting potential.
negatively charged molecules such as proteins are more abundant inside the cells than outside.
threshold potential???
the critical levels at which the membrane potential must be depolarised in order to initiate an action potential.
the fuq are voltage gated K+ channels????
they are LEAKING channels. they tend to be open more often at rating membrane potential. most neurons have 50x more K channels than Na channels.
T/F:at rest the membrane is more permeable to K than Na.
she spits truth.
Action potential??
generated when a stimulus pushes resting pot. o a threshold value. Voltage-gated channels open in the plasma membrane. b/c protein.
the inward flow of the Na+ changes membrane potential from negative to a positive peak. the potential falls to the resting value as gated K+ channels allow ions to flow out.
what is the period of time between the opening of the Na+ channel and the opening of the K+ channels?
1 msec.
refractory period?
action potentials are prevented from reversing direction by a brief refractory period.
this is only a few milliseconds.
how does the inward flow of Na+ alter the electrochemical gradient?
- it produces fall in the membrane potential
- it causes more channels to open
- the happens explosively until all of the available ion channels are open, resulting in a DECREASE in the membrane’s potential.
- the polarity of the plasma membrane reverses, the ions channels rapidly inactivate
- Na+ ions can now no longer enter the neuron and are actively transported out of the plasma membrane.
