When only K+ is considered, net movement of K+ stops when the membrane potential
ID: 3473664 • Letter: W
Question
When only K+ is considered, net movement of K+ stops when the membrane potential is 90mV. Why is this? A) The chemical gradient that is driving K+ diffusion into the cell is opposed by the electrical gradient driving K+ diffusion out of the cell. B) he chemical gradient driving K+ transport out of the cell is opposed by the electrical gradient driving K+ transport into the cell C) The K+ leak channels start to denature as the membrane potential becomes more negative. 2) What type of transport does sodium use to move from the extracellular fluid to the intracellular fluid? A) Active transport B) Simple diffusion C) Facilitated diffusion D) Vesicular transport 3) What is meant when a neuron is said to be "excitable"? A) The neuron contains dendrites that receive electrical signals. B) The neuron can generate electrical signals. C) The neuron has a branching axon. D) The neuron has multiple axons that receive signals. 4) What is true about axons? A) Axons are always long so that they can reach any cell in the body B) There are multiple axons associated with a neuron. C) Axons generate action potentials. D) All of the above. 5) Why might a cell membrane be considered more permeable to K+ than to Na+? A)K+ is a very small and so it can flow through most cell membranes without using a protein channel. BThe cell membrane contains more protein channels for K+. C) Na+ takes longer to pass through its protein channel. D)All of the above.
Explanation / Answer
When only K+ is considered, the net movement of K+ stops when the membrane potential is 90mV. Why is this?
B) The chemical gradient driving K+ transport out of the cell is opposed by the electrical gradient driving K+ transport into the cell
K+ ion predominates inside the cell, as K+ diffuses due to its concentration gradient, it causes the development of an electrical potential difference that acts in the opposite direction on positive ions. So, the diffusion of K+ down its concentration gradient quickly creates an electrical potential difference that completely counterbalances the tendency of K+ to diffuse due to its concentration gradient.
2) What type of transport does sodium use to move from the extracellular fluid to the intracellular fluid?
A) Active transport
3) What is meant when a neuron is said to be "excitable"?
B) The neuron can generate electrical signals.
4) What is true about axons?
C) Axons generate action potentials.
5) Why might a cell membrane be considered more permeable to K+ than to Na+?
B)The cell membrane contains more protein channels for K+.
Cell membranes are considerably more permeable to K+ than to Na+ because they have many more K+ leak channels than Na+ leak channels.
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