You are amazing. I have watched you (your videos) so much in the last couple years I almost feel like I know you! I don't know what I would do without you, Thanks for the hard work!
Just want to thank you from the bottom of my heart for this. Really appreciate your efforts. You have made biology so much more easier for me. Love you
First off, thank you for all your efforts and willingness to share your time and talents. I'm still not quite clear on how the return to resting membrane potential occurs after hyperpolarization. Many sources cite the Na+/K+ pump. This is confusing to me because if 3 positive ions (Na+) are leaving the -90mV cell and 2 positive ions (K+) enter the cell than in my mind the ICF would still have a negative defect in relation to the ECF. Now, we know that K+ is 25-30 times more permeable to the membrane than Na+ is...so is the return to resting potential (-70mV) achieved by lots of K+ crossing the membrane into the cell via leak channels?
Michelle Christian Yes, after the hyperpolarization caused by the opening of voltage gated potassium channels is finished, we return to the resting potential via passive potassium leak channels.
My course states the threshold potential is at -55, but I've noticed a lot of different values, ranging from -60 to -40, is there a correct answer, or is it variable?
I'm unclear whether the voltage gated potassium channels open on a delayed timer from the -45mV threshold or if they are gated to open at +45mV. Along the same lines, do the sodium channels close after ~1ms or after the membrane potential reaches +45mV? I guess I'm just confused on whether these inactivations are based on time or voltage.
Ah, this helped me so much!! I just have one quick question: are the K+ ion channels open during almost the entire cycle (except for when they are blocked towards the end)?
i have a fiancée, I live with him, I truly love him but still I would marry YOU ahah you are the savior of my exams, you defeat my doubts and make me less stressed because I can understand everything
Ashley Hileman Voltage is a relative quantity, you can't talk about it without talking about distance, Voltage is the potential difference between two points. There are more sodium ions on the outside than there are potassium ions on the inside, so it's not equivalent; since the intracellular concentration is less than extracellular, we say it's negative. At least that's how I understand it. For example, we'll say there are just sodium and potassium ions, potassium inside, sodium outside. Say there are 65 sodium ions to 45 potassium ions, if our ground is extracellular, the Voltage across the membrane is -20 mv. If you close that gap and create equilibrium, there is no voltage because there's no concentration gradient. I hope that helps.
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awkward...
I’m reading and I hear his voice. Lmao 😆
Thank you so much for taking time to create these comprehensive videos. I love how you repeat things for a quicker learning.
You are amazing. I have watched you (your videos) so much in the last couple years I almost feel like I know you! I don't know what I would do without you, Thanks for the hard work!
You've been saving my first year at brazilian MedSchool. Thx a lot! Hugs from Brazil.
Thank you for this! Your videos have been very helpful when studying for my A&P exams.
Just want to thank you from the bottom of my heart for this. Really appreciate your efforts. You have made biology so much more easier for me. Love you
Thanks to TH-cam which made it possible to have you here
😊You make my studies more easy and enjoyable. God bless you
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Thank you.It was really helpful for me
Thnk u so much ur lecture makes my doubt clear. I like ur style of giving lecture to us.
This how they teach action potential at the medical school
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Because of your videos I have a masters degree in biology
nicely explained👍👍
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👍 great
First off, thank you for all your efforts and willingness to share your time and talents.
I'm still not quite clear on how the return to resting membrane
potential occurs after hyperpolarization. Many sources cite the Na+/K+
pump. This is confusing to me because if 3 positive ions (Na+) are
leaving the -90mV cell and 2 positive ions (K+) enter the cell than in
my mind the ICF would still have a negative defect in relation to the
ECF. Now, we know that K+ is 25-30 times more permeable to the membrane
than Na+ is...so is the return to resting potential (-70mV) achieved by
lots of K+ crossing the membrane into the cell via leak channels?
Michelle Christian Yes, after the hyperpolarization caused by the opening of voltage gated potassium channels is finished, we return to the resting potential via passive potassium leak channels.
My course states the threshold potential is at -55, but I've noticed a lot of different values, ranging from -60 to -40, is there a correct answer, or is it variable?
I'm unclear whether the voltage gated potassium channels open on a delayed timer from the -45mV threshold or if they are gated to open at +45mV. Along the same lines, do the sodium channels close after ~1ms or after the membrane potential reaches +45mV? I guess I'm just confused on whether these inactivations are based on time or voltage.
game changer
Ah, this helped me so much!!
I just have one quick question: are the K+ ion channels open during almost the entire cycle (except for when they are blocked towards the end)?
probably too late to answer, but the answer is yes
@@shadenyakoub671 Thanks. That helped me though
@@shadenyakoub671 Also, can you tell me what those "balls" he kept referring to are actually called?
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i have a fiancée, I live with him, I truly love him but still I would marry YOU ahah
you are the savior of my exams, you defeat my doubts and make me less stressed because I can understand everything
Would You Marry Baldies?
Mic drop👏
Why does potassium, a cation, carry negative voltage?
Ashley Hileman Voltage is a relative quantity, you can't talk about it without talking about distance, Voltage is the potential difference between two points.
There are more sodium ions on the outside than there are potassium ions on the inside, so it's not equivalent; since the intracellular concentration is less than extracellular, we say it's negative.
At least that's how I understand it.
For example, we'll say there are just sodium and potassium ions, potassium inside, sodium outside. Say there are 65 sodium ions to 45 potassium ions, if our ground is extracellular, the Voltage across the membrane is -20 mv. If you close that gap and create equilibrium, there is no voltage because there's no concentration gradient.
I hope that helps.
Can you please be more precise when explaining an action potential. The post synaptic membrane is actually a Dendrite.
It does not have to be a dendrite.
Thank you🌺🌺🌺🌺🌺🌺🌺🌺🌺🌺🌺🌺🌺💐💐💐💐💐💐💐💐💐🌷🌷🌷🌷🌷🌷🌹🌹🌹🌹🌹🌹🌹🌹🌹🌸🌸🌸🌸🌸🌸🌸🌸🌸🌸🌸🌸