Resting Membrane Potential

Question 1

All cells in the resting stage exhibit a voltage across their membrane. This is called

Answer 1

The resting membrane potential

Question 2

What molecule is in high extracellular concentration and low intracellular concentration?

Answer 2

Sodium (Na)

Question 3

Why is sodium higher on the outside of the membrane than it is on the inside of the cell?

Answer 3

Because the membrane is poorly permeable to sodium.

Question 4

What molecule is in high concentration in the cell and low concentration in the extracellular fluid?

Answer 4

Potassium (K)

Question 5

Why is potassium higher on the inside of the membrane than it is on the outside of the cell?

Answer 5

Because the membrane is permeable to potassium.

Question 6

What is the typical range of resting membrane potential that all body plasma membranes exhibit?

Answer 6

Typically ranges from -50 to -100 milivolts (mV) depending on cell type.

Question 7

What does the minus sign before the voltage indicate?

Answer 7

That the inside of the cell is negative compared to its outside.

Question 8

This voltage (or charge separation) exists only

Answer 8

At the membrane.

Question 9

If all the negative and positive charges in the cytoplasm were added up, what would be found?

Answer 9

You would find that the cell interior is electrically neutral. Likewise for the extracellular fluid.

Question 10

The most well-studied carrier (pump) called Na+ -K+ ATPase, located in all plasma membranes, and involved in primary and secondary active transport of nutrients and ions.

Answer 10

Sodium potassium pump

Question 11

Na+ and K+ channels allow ___ ____ down concentration gradients

Answer 11

Slow leakage

Question 12

Na+ and K+ pump works as antiporter; pumps against Na+ and K+ gradients to maintiain high interacellular __ concentration and higher extracellullar ___ concentration

Answer 12

K+

Na+

Question 13

The Na+ and K+ pump maintains electrochemical gradients essential for functions of

Answer 13

Muscle and nerve tissues, and allows all cells to maintain fluid volume

Question 14

Na+ and K+ pump is an example of

Answer 14

Primary active transport

Question 15

Step 1 of Na+ and K+ pump?

Answer 15

3 cytoplasmic Na+ bind to pump protein

Question 16

Step 2 of Na+ and K+ pump?

Answer 16

Na+ binding promotes hydrolysis of ATP. The energy released during this reaction phosphorylates the pump.

Question 17

Step 3 of Na+ and K+ pump?

Answer 17

Phosphorylation cause the pump to change shape, expelling the Na+ to the outside.

Question 18

Step 4 of Na+ and K+ pump?

Answer 18

Two extracellular K+ bind to the pump

Question 19

Step 5 of Na+ and K+ pump?

Answer 19

K+ binding triggers release of the phosphate. The dephosphorylated pump resumes its original conformation.

Question 20

Step 6 of Na+ and K+ pump?

Answer 20

Pump proteins binds ATP; releases K+ to the inside, and Na+ sites are ready to bind Na+ again. The cycle repeats.

Question 21

What is the point of the Sodium potassium pump?

Answer 21

It is used to move sodium and potassium AGAINST its concentration gradient. Going from an area of high concentration to low concentration takes ATP.

Question 22

Why are all cells considered polarized/

Answer 22

Because all body plasma membranes exhibit a -50 to -100 millivolts depending on cell type.

Question 23

The resting membrane potential is largely determined by ___ because at rest, the membrane is much more permeable to K+ than Na+.

Answer 23

K+