I'm having conflicting information regarding which gates are open/opening vs. closed/closing during different membrane states:
Which of the following voltage gated positions best represents the repolarization phase?
A) m gate open; h gate closed, n gate open.
B) m gate close; h gate closed, n gate open.
C) m gate open; h gate open, n gate open.
D) m gate closed; h gate open, n gate closed.
Here's what information I have, but I really don't feel like this gives me a clear enough picture, and I feel like different sources state different things, so I need clarification please!!!
m-gate:
Resting: Na+ m-gates (activation gates) are closed.
Depolarization: Na+ m-gates are opening, causes others to open.
Repolarization: Na+ m-gates are open at the beginning, but are closing, and closed at the end.
Hyperpolarization: Na+ m-gates are closed.
h-gate:
Resting: open
Depolarization: open, but closes at the end?
Repolarization: closed.
Hyperpolarization: closed.
n-gate:
Resting: K+ n-gates (activation gates) are closed.
Depolarization: K+ n-gates are still closed.
Repolarization: K+ n-gates are opened.
Hyperpolarization: K+ n-gates remain open? slow-to-close, which causes hyperpolarization.
*There are K+ leak-channels that are always open.
Answer: A) m gate open; h gate closed, n gate open.
TBR reasoning:
"During repolarization phase, K+ is flowing out of the cell and down its concentration gradient. If K+ is flowing out of the cell, the n gate must be open. Looking through our choices, we see that the n gate is closed in choice D (eliminate choice D).
We know that during repolarization, we do not want Na+ entering the cell. If Na+ enters the cell as K+ leaves, we will not be able to obtain the resting membrane potential of the cell as quickly as we would like. Which one of the Na+ gates is closed, or are they both closed? We know that during depolarization the h gate begins to slowly close. Let's assume that the h gate has closed as repolarization begins. If this is the case then we can eliminate choice C.
However, all through depolarization Na+ is entering the cell, which means that the m gate is remaining open. By the time the peak of the action potential has occurred, the h gate has closed, the m gate is still open but beginning to close, and the n gate is open."
Which of the following voltage gated positions best represents the repolarization phase?
A) m gate open; h gate closed, n gate open.
B) m gate close; h gate closed, n gate open.
C) m gate open; h gate open, n gate open.
D) m gate closed; h gate open, n gate closed.
Here's what information I have, but I really don't feel like this gives me a clear enough picture, and I feel like different sources state different things, so I need clarification please!!!
m-gate:
Resting: Na+ m-gates (activation gates) are closed.
Depolarization: Na+ m-gates are opening, causes others to open.
Repolarization: Na+ m-gates are open at the beginning, but are closing, and closed at the end.
Hyperpolarization: Na+ m-gates are closed.
h-gate:
Resting: open
Depolarization: open, but closes at the end?
Repolarization: closed.
Hyperpolarization: closed.
n-gate:
Resting: K+ n-gates (activation gates) are closed.
Depolarization: K+ n-gates are still closed.
Repolarization: K+ n-gates are opened.
Hyperpolarization: K+ n-gates remain open? slow-to-close, which causes hyperpolarization.
*There are K+ leak-channels that are always open.
Answer: A) m gate open; h gate closed, n gate open.
TBR reasoning:
"During repolarization phase, K+ is flowing out of the cell and down its concentration gradient. If K+ is flowing out of the cell, the n gate must be open. Looking through our choices, we see that the n gate is closed in choice D (eliminate choice D).
We know that during repolarization, we do not want Na+ entering the cell. If Na+ enters the cell as K+ leaves, we will not be able to obtain the resting membrane potential of the cell as quickly as we would like. Which one of the Na+ gates is closed, or are they both closed? We know that during depolarization the h gate begins to slowly close. Let's assume that the h gate has closed as repolarization begins. If this is the case then we can eliminate choice C.
However, all through depolarization Na+ is entering the cell, which means that the m gate is remaining open. By the time the peak of the action potential has occurred, the h gate has closed, the m gate is still open but beginning to close, and the n gate is open."