Module 2 Flashcards
What is the threshold of excitation that sets the action potential in motion
-40 mV or higher (-35, -30, -20 etc)
what is the name of the potential that causes the charge to meet the threshold of excitation
post-synaptic potential
what are the Sodium (Na+) channels called, and why
voltage-gated Na+ channels, they are called that because they only open when the threshold of excitation is met
when do the voltage-gated Na+ channels open
when the threshold of excitation is met
where does the action potential start and end?
It starts at the axon hillock, travels down the axon, and ends at the axon terminals
Once the voltage-gated Na+ ion channels open what happens next?
sodium ions rush through the first channels and cause depolarization which sets off a chain reaction down the entire length of the axon.
what happens once the action potential reaches the end of the axon
it hits the axon terminals and causes them to release neurotransmitters into the synapse
once neurotransmitters are released into the synaptic cleft what happens to them?
They immediately search for receptor sites in the next neuron and may cause that neuron to fire as well.
Describe the lock and key analogy of neurotransmitters and receptor sites
Receptor sites are the locks and neurotransmitters are the keys. Each receptor site will only open if the correct key or neurotransmitter connects.
How does the domino analogy help to explain the action potential and active conduction?
It is all or nothing. Just like when a row of dominoes is set up in a line, once you push the first domino all the other dominoes fall. Once an action potential starts it creates a chain reaction that continues down the entire length of the axon.
What is the term that explains the all-or-nothing action potential?
This is called active conduction because it actively pushes the charge down the axon.
What happens to the negative charge when the sodium ions rush in.
It changes to a positive charge
What is the term that refers to the charge moving from negative closer to positive and once it reaches zero it has completely done what?
depolarization. Zero-point is depolarized meaning there is no charge.
Once depolarization happens and the negative charge changes to positive because of all the sodium ions rushing in, what happens to the potassium inside the axon?
Potassium (K+) is positively charged so it doesn’t what to be inside anymore so it rushes out of the axon.
In reference to potassium, are diffusion and electrostatic pressure working together or against each other during the action potential?
They join forces. Now electrostatic pressure joins forces with diffusion and tells potassium to get out of the axon.
What are the two terms for when the ions rush in and rush out of the axon?
efflux - going out
influx - going in
What happens when potassium rushes out of the ion following the sodium rushing in.
hyperpolarization
Are sodium/potassium pumps at play during the action potential?
no
Does hyperpolarization end at zero like depolarization?
no hyperpolarization can keep going either way.
Moving away from zero is called what?
hyperpolarization
Moving towards zero is called what?
depolarization
How does Lidocaine affect the action potential?
It blocks the sodium ion gates from opening or puts a cork in it so no sodium gets through and therefore no action potential happens.
Does the post-synaptic potential still happen when you receive Lidocaine, is there still pain being registered?
Yes, the body knows there is pain and the post-synaptic potential still happens but since there is a cork in the sodium ion channels nothing happens to start the action potential, and the message never reaches the axon terminal or the brain.
The glial cells outnumber neurons 10 to l because they are the helper cells, what is their main job?
to create myelin sheaths