Membrane Potential II

Question 1

How can the Na+ pump be blocked?

Answer 1

by interfering with ATP production (e.g., low temperature, cyanide, hypoxia) or by specific drugs

Question 2

The Principle of Electrical Neutrality

Answer 2

bulk solutions have to be electrically neutral

Question 2

The sodium/potassium pump is electrogenic, meaning that _____.

Answer 2

the Vm gets a little more negative than it otherwise would be

Question 2

What opens the inner gate on the sodium/potassium pump?

Answer 2

ATP binding

Question 3

the Donnan Rule equation

Answer 3

[K+]o x [Cl-]o = [K+] i x [Cl-]i

Question 4

Ohm’s Law equation

Answer 4

I = (driving force) x G

Question 5

If the Na+ pump is blocked, _____.

Answer 5

Na+ enters the cell, water follows, and the cell swells

Question 5

The diagnosis of _____ usually is via an electrocardiogram (EKG) to detect cardiac arrhythmias, followed by measuring plasma potassium ion concentration.

Answer 5

hyperkalemia

Question 6

The sodium pump is really an _____ pump.

Answer 6

obligatorily coupled sodium-potassium exchange

Question 8

[K+]o x [Cl-]o = [K+] i x [Cl-]i

Answer 8

the Donnan Rule

Question 8

What drugs block the Na+ pump?

Answer 8

cardiac glycosides, which includes digitalis, ouabain, strophanthidin, and others

Question 9

What happens when the outer gate opens on the sodium/potassium pump?

Answer 9

the affinity changes from Na+ to K+

Question 9

What is a drastic way to cleanse potassium from the blood?

Answer 9

dialysis

Question 10

What is the typical cell membrane resting potential?

Answer 10

-80 mV

Question 11

What is G in Ohm’s Equation?

Answer 11

1/R

Question 13

What is the sodium/potassium pump ratio?

Answer 13

3 Na+ for 2 K+

Question 15

The Na/K pump is “_____”, that is, it has an easily demonstrable maximum rate of activity of only about 100 cycles per second.

Answer 15

saturable

Question 16

In acute hyperkalemia, the main danger concerns the reliable conduction of electrical signals (action potentials) in ___.

Answer 16

the heart

Question 17

Both ____ and ___ ions must be present simultaneously or the pump won’t work.

Answer 17

Na+; K+

Question 18

What closes the outer gate on the sodium/potassium pump?

Answer 18

phosphate dissociates

Question 19

What does R stand for in Ohm’s Equation?

Answer 19

membrane resistance to the ion

Question 20

The higher the permeability, the _____ the conductance..

Answer 20

higher

Question 21

Membrane potential is determined by relative ______.

Answer 21

conductance

Question 22

What does V stand for in Ohm’s Equation?

Answer 22

the driving force of the ion

Question 24

What closes the inner gate on the sodium/potassium pump?

Answer 24

ATP splitting, leaving the phosphorylation

Question 25

Hyperkalemia is caused from _____.

Answer 25

loss of potassium from cells

Question 26

In real cells, the big ions (mostly proteins, SO4, and HPO4) carry a net ____ charge.

Answer 26

negative

Question 27

The diagnosis of hyperkalemia usually is via an ___ to detect cardiac arrhythmias, followed by measuring ____.

Answer 27

electrocardiogram (EKG); plasma potassium ion concentration

Question 29

What does I stand for in Ohm’s Equation?

Answer 29

the current

Question 30

Why does K+ leave the inside of the sodium/potassium pump?

Answer 30

the gate opened and the affinity shifted to Na+

Question 31

What does a steady state mean?

Answer 31

ion concentrations aren’t changing over time, but a constant input of energy is needed to drive pumps to keep it this way

Question 32

The sodium/potassium pump is comprised of a large ____ subunit and a smaller ____ subunit.

Answer 32

alpha; beta

Question 33

______ is determined by relative conductance.

Answer 33

Membrane potential

Question 34

In ____, the main danger concerns the reliable conduction of electrical signals (action potentials) in the heart.

Answer 34

acute hyperkalemia

Question 35

What provides the energy for the sodium/potassium pump?

Answer 35

ATP

Question 36

Why do different cells in the body have different resting membrane potentials?

Answer 36

differences in relative permeability

Question 37

The Na/K pump is “saturable”, that is, it has an easily demonstrable _____ of only about 100 cycles per second.

Answer 37

maximum rate of activity

Question 38

When you CBIGK in a patient, what should you give, in order?

Answer 38

Calcium, Bicarb, Insulin + Glucose, Kayexalate