Quiz - CH 05 Resting Membrane Potential and Local Control

Which of the following would cause a pancreatic beta cell to secrete insulin?

K⁺ leaves the cell

 

concentration of glucose in the blood decreases

 

voltage-gated Ca²⁺ channels open

 

the concentration of ATP in the cell decreases

voltage-gated Ca²⁺ channels open

For an ion such as Na⁺, if there is a large "electrochemical gradient" across the plasma membrane , it means:

Note: you may select some, all, or none of the options below.

If the plasma membrane is (or becomes) permeable to Na⁺, Na⁺ will move across the plasma membrane.

 

the concentration of Na⁺ across the plasma membrane has reached equilibrium.

 

there may be a concentration gradient for Na⁺ across the plasma membrane.

 

there may be an electrical gradient across the plasma membrane (i.e. one side of the plasma membrane has more positive charges and the other side has more negative charges).

If the plasma membrane is (or becomes) permeable to Na⁺, Na⁺ will move across the plasma membrane.

there may be a concentration gradient for Na⁺ across the plasma membrane.

there may be an electrical gradient across the plasma membrane (i.e. one side of the plasma membrane has more positive charges and the other side has more negative charges).

If a cell is depolarized, it has a membrane potential,

 

more positive than resting membrane potential.

 

more negative than resting membrane potential.

 

more positive than 0 mV.

 

more negative than 0 mV.

more positive than resting membrane potential

The resting membrane potential results from all of the following except:

 A greater permeability of the cell membrane to K⁺ than to Na⁺

The presence of chemically gated Na⁺ channels in the plasma membrane

A higher concentration of K⁺ inside the cell than outside the cell

The activity of the sodium/potassium pump

The presence of chemically gated Na⁺ channels in the plasma membrane