BIOL 121 Lecture Notes - Lecture 6: Resting Potential, Threshold Voltage, Sodium Channel

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ochrehornet578

21 Jun 2020

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Concentration gradients of ions across the membrane. Sodium, chloride, calcium are concentrated in the extracellular fluid. Potassium is more concentrated in the cytoplasm. Resting cell membrane is much more permeable to potassium that to sodium or calcium, which makes potassium the major contributor to the resting membrane potential. The goldman hodgkin katz equation is used to calculate the resting membrane potential that results from conctribution of all ions that can cross the membrane influence its contribution the membrane potential. Includes membrane permeability values because he permeability of an ion will. If membrane is not permeable to an ion then that ion will not affect the. Vm=61 log (pk[k+]out+pna[na+]out+pcl[cl-]in) / ( membrane potential. Ion movement across the cell membrane creates electrical signals. If a cell increases sodium permeability, sodium will move down its electrochemical gradient into the cell, causing the intracellular fluid to depolarize.

Related Questions

Which of the following is FALSE regarding the membrane potential? A. The resting membrane potential is determined mainly by the concentration gradients and differential permeability of the plasma membrane to K+ and Na+ions. B. The resting membrane potential occurs due to active transport of ions across the membrane due to the sodium-potassium pump. C. In their resting state, all body cells exhibit a resting membrane potential. D. The resting membrane potential is maintained by solely by passive transport processes.

1. The plasma membrane of rod and cone cells are

a) At resting potential in the dark and deploarized in thelight

b) At resting pootential in the dark and hyperpolarized in thelight

c) Depolarized in the dark and hyperpolarized in the light

d) Hyperpolarized in the dark and at resting potential in thelight

e) Hyperpolarized in the dark and depolarized in the light

2. The equilibrium potential of K+ ions in nerve cells is about-90mV. The membrane potential of a typical nerve cells at rist is-70mV. Therfore

a) Increasing the permeability of a resting neuronal membrane toK+ ions will increase the membrane potential (that is, make it morenegative, inside with respcect to outside)

b) In nerve cells at rest, there is a net diffusion of K+ ionsout of the cell

c) Increasing the membrane potential of a nerve cell would slowthe diffusion of K+ ions out of it.

d) K+ is not the only ion that is permeable at rest

e) All of the above

3. Which of the following is responsible for the replarizingphase of the action potential?

a) Voltage-gated Na+ channels are opened.

b) The Na+-K+ pump restores the ions to theri original restingstate.

c) The permeability to Na+ increases greatly.

d) ATPase destroys the energy supply that was maintaining theaction potential at its peak.

e) The permeability to K+ increases greatly while that to Na+decreases

4. The Relative refractory period of an axonm conincides withthe period of

a) Activation and inactivatioin of voltage-gated Na+channels

b) Increased Na+ flux into the cell

c) Increased K+ flux into the cell

d) Increased K+ flux out of the cell

e) Increased Na+ flux out of the cell

5. The plasma membranes of rod and cone cells are

a) At resting potential in the dark and epolarized in thelight

b) At resting potential in the dark and hyperpolarized in thelight

c) Depolarized in the dark and hyperoplarized in the light

d) Hyperpolarized in the dark and tat resing potential in thelight

e) Hyperpolarized in the dark and depolarized in the light

(1) What would be thelikely outcome if an increase in both intracellular sodium ionlevels and extracellular potassium ion levels were tooccur?

A: The Na+-K+ pump would accelerate because it needs to restorethe membrane's resting concentration gradient.

B: The Na+-K+ pump would slow down because it needs to restorethe membrane's concentration gradient.

C: Sodium and Potassium ions would be pumped out of thecell.

D: Sodium and Potassium ions would increase their movement inboth directions across the cell membrane.

(2) Due to the unequal transport of sodium and potassiumions by the Na-K pump, a membrane potential isgenerated.

True or False

(3) If a pump moves 3 positive ions out and 2 positiveions in against their concentration gradients, the membranepotential in the cell will become more positive.

True or False

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BIOL 121 Lecture Notes - Lecture 6: Resting Potential, Threshold Voltage, Sodium Channel

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