GENIUS FORUMS

Liz wrote:

Nope, no questions. Now I fully understand why your professor could not explain action potential to you in a way that would "jive" with your mind.

So that little essay I wrote on resting potential was completely greek to you then?

Liz: answers a & b did tell you what stage the action potential is in. it is at -90mV

There are four stages to an action potential, each stage has a label. Can you name what they are, smartass?

If not, then to say the action potential is at -90mv means nothing.

Milli: I never counted on being called Milli, for the record. :)

Which one are you?

http://991.com/newgallery/Milli-Vanilli ... 196589.jpg


You'll have to get back into the studio, and remix blame it on the rain.

'blame it on elitism' ?

Cory Duchesne wrote:There are four stages to an action potential, each stage has a label. Can you name what they are, smartass?

Depolarization, repolarization, refractory period, and propagation.

At -90mV, it would have to be in the repolarization phase.

And I'm glad that you think that some part of me is smart.

It is better to be a smartass than a dumbass.
-David Seibert

Actually your wrong.

It would be the refractory period.

Ryan was right, the answer is A.


But I don't think you are stupid for not being able to handle the question.

The question is poorly worded.

For instance:

What effect will this have on the equilibrium potential of potassium?

Potasium can't have an equilibrium potential. To say that a paticular molecule, or an isolated group of ions possess an equilibirum potential is nonesense.

There is only the inside of the neuron being relatively negative in relationship to the more relatively positive outside of the neuron.

The outside is a sea of charged ions, the inside is a sea of charged ions.

The question sucks.

Cory wrote:

Actually your wrong.

Don’t worry Elizabeth, whenever I do something or think something wrong, I immediately crank up this song and sing it as loudly, sincerely and as passionately as I can. Try it, it will make you feel better, it always makes me feel better.

http://www.youtube.com/watch?v=rpTClxdBG9c

Cory Duchesne wrote:Potasium can't have an equilibrium potential. To say that a paticular molecule, or an isolated group of ions possess an equilibirum potential is nonesense.

Potassium is like the gas and the neuron is like the car. You need the gas to make the car go, but it is the car that goes. So although it would more literally be the car (neuron) that goes, the potential for it to go depends on the presence of gas (K+). Literally you are correct that it is the neuron that has the action potential, not the potassium - but the techinical phrase is "potassium equilibrium potential."

You got the quiz back and the answer was A? Or that is your assertation?

The period of time during which an excitable cell cannot generate another action potential is called the refractory period.
Principles of Anatomy and Physiology, 8th ed. Tortora, G. & Grabowski, S. HarperCollinsCollegePublishers, 1996.

There are four stages to an action potential, each stage has a label. Can you name what they are, smartass?

If not, then to say the action potential is at -90mv means nothing.

but now you're sure that -90mV is in the refractory stage and you're sure that the stage was not indicated in the question? Sounds circular to me.

Cory: Potasium can't have an equilibrium potential. To say that a particular molecule, or an isolated group of ions possess an equilibrium potential is none-sense.


Potassium is like the gas and the neuron is like the car.

That is incorrect. If anything is the gas, it’s sodium. For instance, during depolarization (the first stage), sodium gates are opened, and sodium floods in, and if enough sodium manages to flood in, an action potential is triggered.
So it begins with the cell resting at approximately -70mv, and once the gates open, the voltage climbs toward the threshold (-55mv). If it reaches the threshold, well that’s like pushing the shudder button on a camera. “Flash!” A surge of aprox. +40mv charge gets fired down the axon of the cell. It’s all or nothing. If depolarization reaches -54mv, then nothing occurs.

Anyways, after the +40mv pulse travels to the end, the votage drops down to aprox. -90mv, and then slowly pumps itself back up to -70mv.

Eliz: You need the gas to make the car go, but it is the car that goes.

Actually no, the neuron doesn’t go anywhere. It shoots electric charges (which aren’t powered by potassium)

Eliz: So although it would more literally be the car (neuron) that goes, the potential for it to go depends on the presence of gas (K+).

I’ll admit that K+ plays a vital role. But your analogy is still bad.

Literally you are correct that it is the neuron that has the action potential, not the potassium - but the technical phrase is "potassium equilibrium potential."

Well your reasoning behind why it’s called the ‘potassium equilibrium potential’ is wrong.

So I’m going to have to consider the so-called technical term foolish until you or someone gives me a better explanation of the role K+ plays.

Ellz: You got the quiz back and the answer was A? Or that is your assertation?

No, I didn’t get the quiz back, but I know that just because a cell is in the refractory period (also known as a state of ‘hyper-polarization’) doesn’t mean that potassium isnt gathering on the outside of the cell when it is in that state.

After all, the Quiz question says that K+ is gathering on the outside of the cell. It has nothing to do with whether or not the neuron is capable of firing another pulse.

Cory: There are four stages to an action potential, each stage has a label. Can you name what they are, smartass?

If not, then to say the action potential is at -90mv means nothing.

Eliz: but now you're sure that -90mV is in the refractory stage and you're sure that the stage was not indicated in the question? Sounds circular to me.

Did I say that it was impossible to determine what stage the action potential was at based on the information given on the quiz?

No. All I said was that for you to merely assert that -90mv means that the action potential is at -90mv is meaningless unless we determine what stage of the action potential is at.

The reason I italicized 'you' was to show that someone who hasnt taken the time to understand this, has no right to patronize and make fun of someone trying to understand.

Not that I care if you make fun of me. But I don't let arrogance slide. No, I dont mean the sort of David Quinn arrogance. No, not that. I mean arrogance towards truth. If you're truthful, be arrogant all you want. But if you dont have a clue what your talking about, well then you have some maturing to do.

You are very naughty today Elizabeth!

I'm looking for people who can admit they don't know, in order to explore with them. You don't seem to know what that means. I think its because you are very quick to grab on to the 'what' rather than humbly ask 'why'.

I think I started a thread on something about 'the what and the why' not too long ago.....

But I hope you continue with me on this...

Dont stop now. Surely you must by now have some intelligent questions.

Cory,

I am certainly not trying to make fun of you. In fact, that question looks quite similar to one that I had on an A&P exam I took OMG years ago, and I got it wrong - which was why I remember so clearly the discussion I had with the professor after the test.

The intent of my initial response was to help you. I like you Cory, and I want to see you do well. I was sure that i knew what I was talking about, and I do say that I am not sure when I am not so sure. My reaction to your disagreement was defensive due to my particular relationship with Reality. I suppose that defensiveness showed through, and if it hurt you in any way, I apologize.

No, of course you didnt hurt me. It takes a great deal more than that.

I see you as part of my self and I was a bit dissatisfied with myself, that's all.

I 'am' my relationship to others(to reality), and I'm always looking for ways to improve myself (my relationship to reality, to others).

Improving your relationship to reality may involve hurting the people in your life by showing them to themselves, or sometimes it involves hurting them by leaving them trapped in their own ignorance by abandoning them completely.

It all has very little to do with making people happy.

Earlier........

Cory: There are four stages to an action potential, each stage has a label. Can you name what they are, smart-ass? If not, then to say the action potential is at –90mv means nothing.

Eliz: At -90mV, it would have to be in the repolarization phase.
And I'm glad that you think that some part of me is smart.

Cory: Actually you’re wrong. It would be the refractory period. Ryan was right, the answer is A.

Liz: But now you're sure that -90mV is in the refractory stage and you're sure that the stage was not indicated in the question? Sounds circular to me.

Cory: Did I say that it was impossible to determine what stage the action potential was at based on the information given on the quiz?

No. All I said was that for you to merely assert that -90mv means that the action potential is at -90mv is meaningless unless we determine what stage of the action potential is at.

Ok, so I want to revisit something I said when I first opened up this thread:

Cory: Is it just me - or wouldn’t it make sense for a question like this to inform you what the stage is of the particular action potential that we are dealing with? If we are not informed in such a way, should we even regard the question as sensible or fair?

Ok, so I’ve come to admit that knowing what stage the action potential is at, isn’t vital for the answering the question. However, my understanding of all of this still isn’t at the level that I can explain to Elizabeth why the equilibrium potential for potassium changes in accordance to the quantity of potassium that is present on the outside of the cell.

What is vital is understanding this: “equilibrium potential of potassium” concept.

Taken from Wikipedia:

Equilibrium potentials
For most animal cells potassium ions (K+) are the most important for the resting potential[1]. Due to the active transport of potassium ions, the concentration of potassium is higher inside cells than outside. Most cells have potassium-selective ion channel proteins that remain open all the time. There will be net movement of positively-charged potassium ions through these potassium channels with a resulting accumulation of excess positive charge outside of the cell. The net movement of positively-charged potassium ions is due to random molecular motion (diffusion) and continues until enough excess positive charge accumulates outside the cell to form a membrane potential which can balance the difference in concentration of potassium between inside and outside the cell.
"Balance" means that the electrical force that acts to move the ions tends to increase until it is equal in magnitude but opposite in direction to the tendency for net movement of potassium due to diffusion. This balance point is an "equilibrium potential". Potassium equilibrium potentials of about -70 millivolts are common in neurons.

You see, why is this mostly gibberish to me? I truly think that whoever wrote that little bit in wikipedia doesn’t think holistically well at all. That’s the problem with academics.

They live in a perpetual state of superfluous-ness and redundancy.

BUT, I did understand the above paragraph enough to know that ‘pottasium equilibrium potentials’ increase to the degree that potassium gathers on the outside of the cell.

Therefore Elizabeth, I’m pretty confident that ‘C’ is the wrong answer. But look, I know my tone revealed a bit of irritation towards you on previous posts. I’ll admit, I was irritated by you, and became aggressive and loud mouthed. I was weak. Sure. No problem. Moving on. And look, I’m very open to the possibility that I am wrong, and no, not because I feel confident that I'm right! So I encourage you to stick with me on this.

You see, I think Ryan and I might have been wrong for saying the answer was A.

Perhaps the answer is B. The reason I think B is because, if you add potassium to the outside of the cell, then that increase of positive ions creates a steeper charge accross the membrane. In other words, the voltage difference between the inside and the outside increases from -70mv to -90mv Or -90 to -100 depending on what stage of the action potential you are at. Either way, it gets more negative, not more positive.

So I'm thinking A is wrong. But I maintain that C is wrong as well. B sounds right to me.

Equilibrium potential is a word that basically describes what is essentially a difference between the voltage inside a cell, and the voltage outside the cell. So, the greater the ammount of positive ions there are on the outside of the cell, the greater the difference will be between the voltage inside compared to the voltage outside. You know, If there are hardly any positive ions on the outside of the cell, then it would be close to 0. If you added some postive ions, the voltage difference would get steeper and go down to -30mv. Add some more; -70mv. Etc, etc.

So to increase the ammount of ANY positive ion, whether it is sodium or potassium, results in a steeper equilibrium potential.

The more negative the number, the steeper the equilibrium potential is. And the steeper the equilibirum potential is, the more you will find that there is a much larger population of positive ions on the outside- compared to the inside.


Anyways,

What doesn’t make sense to me is this: Why do we say that there is a specific type of equilibrium potential that is attributed solely to potassium? Why do we say 'the potassium equilibirum potential?'

It Makes no sense to me.

Shouldn’t the equilibrium potential be attributed only to the membrane as a whole?

Cory wrote:

Why do we say 'the potassium equilibirum potential?'

Who knows? That's just the name that somebody gave it. As a comedian pointed out, we drive on a parkway and park on a driveway.

Answer B is better than answer A, because over time the charge could increase. The problem is that answer B has the charge increasing to -100mV and the ranges are from -40mV to -90mV. It's out of range. The body has a funny way of really needing to stay within certain ranges or parts of it that are out of range die.

What makes no sense to me is why they are testing you on some fairly advanced concepts of anatomy and physiology in a semester 1 psych class. They should be teaching you about S. Freud, A. Freud, Jung, Adler, Maslow's Hierarchy of Needs... that kind of stuff.

Eliz wrote,

What makes no sense to me is why they are testing you on some fairly advanced concepts of anatomy and physiology in a semester 1 psych class. They should be teaching you about S. Freud, A. Freud, Jung, Adler, Maslow's Hierarchy of Needs... that kind of stuff.

Our first lecture, and the first chapter in our text book was big on illustrating a certain persepctive of 'the history of psychology'. Jung, Alder, and Maslow were left out.

But for the most part, we werent tested on that. Our midterm was 80% focused on a trivial, idiosyncratic and a fragmented way of approaching neuro-biology.

Which I've been feeling a bit irritated by over the past two weeks.

I think that by designing a course that focuses on fragmented conceptions of causality happening at the neurological level, it prepares students to think that that is where they should look when it comes to solving emotional and social problems.

Which is a shame.

A course, especially when it is an intro, should approach the subject as holistically as possible.

But I think this is about money, it's about sheer numbers, quantity, and not about learning and quality.

Eliz wrote,

The problem is that answer B has the charge increasing to -100mV and the ranges are from -40mV to -90mV. It's out of range. The body has a funny way of really needing to stay within certain ranges or parts of it that are out of range die.

Yes, now see that I would find very interesting to learn about at this stage. I'd would like to know all of the general rules in contrast to the exceptions to the general rule when it comes to neurobiology. Once one gets that down pat, then one will probably find the sorts of questions like the one we're dealing with on this thread, are worthless.

On the test we had a question like: "A martian from another planet has neurons with resting potentials of +80, and on the outside of the neuron, there is a bit of Cl - added to an existing concentration. Will the Cl equilibirim potential increase or decrease?

Something like that. A bunch of shit like that.

Cory Duchesne wrote:On the test we had a question like: "A martian from another planet has neurons with resting potentials of +80, and on the outside of the neuron, there is a bit of Cl - added to an existing concentration. Will the Cl equilibirim potential increase or decrease?

Without knowing anything about Martian physiology, one could not know the answer.

Once one gets that down pat, then one will probably find the sorts of questions like the one we're dealing with on this thread, are worthless.

Yes, the question is worthless. Why would someone add K+ to the outside of a perfectly healthy neuron? For practical purposes, the only reason would be to kill the individual. One could add K+ for someone who was potassium deficient to help them get better or save their lives, but that was not the question.

A course, especially when it is an intro, should approach the subject as holistically as possible.

Agreed on two levels. Not only should it be an overview, but it should be an overview of the subject being introduced.

duplicate.

Cory Duchesne wrote:But I think this is about money, it's about sheer numbers, quantity, and not about learning and quality.

I think it's about bad ideas and miscommunication. I think at the begining when the program was being formed, Intro to Psyc was a good idea. Who knows who came up with the curriculum, or if the original curriculum matches what they teach today, but I doubt that the right people are even aware the the Intro to Psychology class actually has a curriculum of Intro to Neurobiology. Since the people who can do something about it are probably not even aware of the problem with the curriculum, this is your opportunity to help hange your corner of the world.

Next, understand about college politics. The students don't normally see this, but college professors and PhDs working at a college tend to have a really big ego structure in place. It can get ugly, and it gets in the way of communication.

It is about money, but it isn't supposed to be all about the money. You are a student, you are paying the bill, so you have more say-so than the teachers actually do. The tricky part is that students were raised in schools where the teachers had all the power and authority, and nobody bothered to tell them that once they got to college, they became consumers, and it became the college's job to make them happy with their educational experience.

Okay, you can't change your class that you are in now. The system works a little slowly, but changing the system is possible. Start off with your teacher by telling her what you think Intro to psyc should be teaching instead. There's no need to be confrontational, it sounds like she's even less interested in the material than you are, so she probably thinks it's a stupid curriculum, too. She's probably mandated to teach that curriculum. Find out from her who to talk to about your "feelings" (psyc teachers like it when you use the word "feelings") about a better curriculum. (Once you get over to administartion, you can change "feelings" to "thoughts"). Keep following the chain until you get to someone who listens. Go over to administration prepared - have a neat copy of your curriculum, your book, any handouts, and show them what is actually being taught. Highlight the subject matter and downplay any difficulties you are having as a student. Approach them in a business-like manner as a consumer interested in product improvement, not like a struggling student. And there's no need to be confrontational about any of it; just remember that the right people just were not aware of what is actually going on, and the ones who are aware of what's going on lack the power to do any good, and lack whatever it takes to talk openly with whoever really needs to know. The communication system's broken, that's all. There is a chance you, as a student, can do something to improve your college that no one else has the position to do.

***********************
edited to add one more idea.

boo-hoo. The answer is A. Oh well.

After the sodium floods in bringing it up to +40, 'I'm guessing' that an equivilent ammount of potassum gets forced out, bringing it back down. More potassium must go out then sodium goes in then, how else could you explain a refractory period of as low as -90mv?

And then when it hits its nadir of -90mv, it raises up to -75

But answer A says that potassium brings it up, from -90mv
to -75mv.

This makes no sense because we also learned that pumps are what bring the refractory period up from -90mv to -70mv by sending 3 sodium out for every 2 potassium that are brought in.

Potassium gathering on the outside implies that the cell is in a state of repolarization, which means both that potassium are being ejected and the voltage is going down.

If that is the correct answer, then I concede.

well, the question is hardly reasonable

Perhaps the real problem here guys is that both of your body’s neurons aren’t firing fast enough to figure out the subtlety of the problem at hand…

I don’t want to boast, but from the first millisecond after I popped out of my mother’s uterus I had lightning fast neurons…

Here is a picture of me in my later years.