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Re: Anatomy & Physiology B/C

Posted: May 30th, 2016, 12:35 pm
by varunscs11

According to this site, the answer was A because "Depolarization of the plasma membrane occurs if there is an increase in the extracellular K+ ion concentration. Hyperpolarization would occur if the extracellular K+ ion concentration decreased, not increased."
I chose B because when the extracellular K+ ion concentration increases, the inside of the plasma membrane becomes more negative relative to the outside of the plasma membrane, causing hyperpolarization. Hyperpolarization occurs when the membrane potential becomes more negative. I assumed that the K+ ion concentration inside the cell stayed the same, and the concentrations of other ions also stayed the same. Where have I gone wrong?
Not very familiar with nervous yet, but I'm pretty sure that's where. The cell membrane is apparently fairly permeable to K+. Intracellular K+ will want to diffuse down its gradient, but it's also being attracted by intracellular anions, so the equilibrium is established: At RMP, there is 40x more K+ inside the cell than outside. Add extracellular K+ and reconsider the equilibrium. The anions stay the same, but there is less of a gradient, so K+ will want to diffuse less, and an intracellular buildup will occur. Therefore, K+ doesn't stay the same. So more positive inside means more positive voltage, meaning depolarization.
I know there's a detail or two somewhere that is wrong :/
I agree. This is a tricky question. I think you may have gotten it mixed up with IPSP's where K+ or Cl- channels open and K+ diffuses out or Cl- diffuses in. But in the case of IPSP's, the ions are moving while in the question you're just increasing the amount of K+ outside the cell so since what causes hyperpolarization is the K+ leaving the cell, you get depolarization in this case (the K+ ions aren't leaving so no accumulation of negative charge). Uber explained it correctly. Just remember that the cell is going to want to do whatever is most stable (like atoms), so if you disturb the equilibrium (#lechateliers) by adding more K+ outside the cell, the K+ will want to diffuse in through leakage channels (because remember the membrane is more permeable to K+), trying to restore RMP and this inward movement will mean more K+ ions so the inside will be more positive relative to the original charge inside (originally negative) (#journeay--> only lasa people will get this)

Re: Anatomy & Physiology B/C

Posted: May 30th, 2016, 2:39 pm
by mangothecat

According to this site, the answer was A because "Depolarization of the plasma membrane occurs if there is an increase in the extracellular K+ ion concentration. Hyperpolarization would occur if the extracellular K+ ion concentration decreased, not increased."
I chose B because when the extracellular K+ ion concentration increases, the inside of the plasma membrane becomes more negative relative to the outside of the plasma membrane, causing hyperpolarization. Hyperpolarization occurs when the membrane potential becomes more negative. I assumed that the K+ ion concentration inside the cell stayed the same, and the concentrations of other ions also stayed the same. Where have I gone wrong?
Not very familiar with nervous yet, but I'm pretty sure that's where. The cell membrane is apparently fairly permeable to K+. Intracellular K+ will want to diffuse down its gradient, but it's also being attracted by intracellular anions, so the equilibrium is established: At RMP, there is 40x more K+ inside the cell than outside. Add extracellular K+ and reconsider the equilibrium. The anions stay the same, but there is less of a gradient, so K+ will want to diffuse less, and an intracellular buildup will occur. Therefore, K+ doesn't stay the same. So more positive inside means more positive voltage, meaning depolarization.
I know there's a detail or two somewhere that is wrong :/
I agree. This is a tricky question. I think you may have gotten it mixed up with IPSP's where K+ or Cl- channels open and K+ diffuses out or Cl- diffuses in. But in the case of IPSP's, the ions are moving while in the question you're just increasing the amount of K+ outside the cell so since what causes hyperpolarization is the K+ leaving the cell, you get depolarization in this case (the K+ ions aren't leaving so no accumulation of negative charge). Uber explained it correctly. Just remember that the cell is going to want to do whatever is most stable (like atoms), so if you disturb the equilibrium (#lechateliers) by adding more K+ outside the cell, the K+ will want to diffuse in through leakage channels (because remember the membrane is more permeable to K+), trying to restore RMP and this inward movement will mean more K+ ions so the inside will be more positive relative to the original charge inside (originally negative) (#journeay--> only lasa people will get this)
Ohhh I see now. Thanks guys for explaining it so well!

Re: Anatomy & Physiology B/C

Posted: August 2nd, 2016, 12:42 pm
by Unome
Pls contribute to the brand new Sense Organs page. It currently contains only copypasted info from the Nervous System page.

Re: Anatomy & Physiology B/C

Posted: August 5th, 2016, 2:42 pm
by Fluorine
Pls contribute to the brand new Sense Organs page. It currently contains only copypasted info from the Nervous System page.
I have some SSSS notes I am finishing up for A&P (I know waiting till last minute again!!). So will add some info to the Sense Organs page once finished with those notes.

Re: Anatomy & Physiology B/C

Posted: August 9th, 2016, 5:19 pm
by Cherrie_Lan
Are we going to be tested on specific nerves this year, much like muscles from last year? For example, the sciatic nerve is located where, and what does it control?

Re: Anatomy & Physiology B/C

Posted: August 10th, 2016, 4:27 am
by Unome
Are we going to be tested on specific nerves this year, much like muscles from last year? For example, the sciatic nerve is located where, and what does it control?
When I did nervous in 2014 we were never tested on specific nerves, but it's probably better to know them anyway (or at least have them typed up).

Re: Anatomy & Physiology B/C

Posted: August 10th, 2016, 8:33 am
by Cherrie_Lan
Okay, thanks!

Re: Anatomy & Physiology B/C

Posted: August 12th, 2016, 9:20 pm
by Fluorine
I met with my partner recently to discuss our studying plans for A&P this year and we ran into a bit of an issue. One of the things we found difficult with the systems this year is that nervous spans a large amount of content so naturally, it makes sense to want to split some of the content we are each going to learn for the event. However, what we realized was that if A&P was run where a simple exam is given with one section for each system where you need to split the work in order to finish how would we go about this. One thing is that if one person only knows half of the nervous system information they would not be able to complete the nervous system part of the test without the other person helping. So my question is what does everyone think is the best way to prepare with your partner for this event? Should we evenly split the content or just both learn everything?

Re: Anatomy & Physiology B/C

Posted: August 16th, 2016, 5:27 pm
by [NerdyTotoro]
I met with my partner recently to discuss our studying plans for A&P this year and we ran into a bit of an issue. One of the things we found difficult with the systems this year is that nervous spans a large amount of content so naturally, it makes sense to want to split some of the content we are each going to learn for the event. However, what we realized was that if A&P was run where a simple exam is given with one section for each system where you need to split the work in order to finish how would we go about this. One thing is that if one person only knows half of the nervous system information they would not be able to complete the nervous system part of the test without the other person helping. So my question is what does everyone think is the best way to prepare with your partner for this event? Should we evenly split the content or just both learn everything?
I think you guys should evenly split the content but then review each other's content to make sure you at least know a good part of the subject (maybe you guys could make a note sheet on your own subject and review the note sheets together).

Re: Anatomy & Physiology B/C

Posted: August 16th, 2016, 7:26 pm
by Fluorine
I met with my partner recently to discuss our studying plans for A&P this year and we ran into a bit of an issue. One of the things we found difficult with the systems this year is that nervous spans a large amount of content so naturally, it makes sense to want to split some of the content we are each going to learn for the event. However, what we realized was that if A&P was run where a simple exam is given with one section for each system where you need to split the work in order to finish how would we go about this. One thing is that if one person only knows half of the nervous system information they would not be able to complete the nervous system part of the test without the other person helping. So my question is what does everyone think is the best way to prepare with your partner for this event? Should we evenly split the content or just both learn everything?
I think you guys should evenly split the content but then review each other's content to make sure you at least know a good part of the subject (maybe you guys could make a note sheet on your own subject and review the note sheets together).
Thanks for the response. That is sort of the plan we ended up agreeing on splitting the content and then reviewing the notes we each have together.