Equilibrium Potential

Question 1

Sodium (Na)/Potassium(K) pump

Answer 1

ATP powered pump drives concentration gradients of ions across membrane. Builds and maintains potassiums concentration gradient in neurons. 75% of all ATP powers the Na+/K+ pump. K+ in, Na+ out.

Question 2

concentration gradient

Answer 2

is the process of particles, which are sometimes called solutes, moving through a solution or gas from an area with a higher number of particles to an area with a lower number of particles. The areas are typically separated by a membrane

Question 3

When will potassium stop leaving the cell?

Answer 3

when the force of the concentration gradient is equal and opposite of the electrical gradient.

Question 4

electrical gradient

Answer 4

refers to the electrical potential that acts on an ion to drive the movement of the ion in one or another direction

Question 5

What is the equilibrium potential?

Answer 5

The membrane potential at which the force of an ion’s concentration gradient is equal and opposite to the ion’s electrical gradient.

Question 6

What are ions always trying to do in a cell?

Answer 6

Ions is are always trying to drive the cell to the equilibrium potential for that ion.

Question 7

When an ion channel opens (any ion channel), Allowing an ion to flow, It will flow until It gets to its __________?

Answer 7

Equilibrium potential

Question 8

Add its own particular Equilibrium potential, The ion is in equilibrium. So what does that mean in regards to the current or net flow?

Answer 8

There will be no current and no net flow.

Question 9

How do neurons generate a membrane potential?

Answer 9

Ions themselves can generate a voltage difference across the membrane if: (1)There is concentration gradient (Difference in concentration in versus out) (2)There is a selective ion channel that allows The ion to flow by itself.

Question 10

Why is the cell negative when there is a high concentration of K+ ions inside the cell? Shouldn’t that make the inside of the cell more positive?

Answer 10

It’s all about what potassium leaves behind in the cell as it flows down its concentration gradient. (negative anions)

Question 11

How do you calculate the equilibrium potential?

Answer 11

Use the Nernst equation.

Question 12

Explain the equilibrium potential of potassium.

Answer 12

Potassium is a positive ion. When the concentration of potassium is high inside the cell, It’s equilibrium potential is negative because you would need to get the cell to be negative in order to stop potassium from flowing out.

Question 13

What builds and maintains potassiums concentration gradient in neurons?

Answer 13

Sodium/potassium pump

Question 14

Define equilibrium for an ion (within the context of the neuronal membrane). Your answer should mention forces.`

Answer 14

An ion is at equilibrium when the force of its concentration gradient is equal and opposite to the force of it’s electrical gradient.

Question 15

What’s the purpose of an ion channel?

Answer 15

To provide a pathway for charged ions To flow across the membrane

Question 16

What creates an ionic current in a cell?

Answer 16

The movement of a charged ion through the channel over time Movement of charge THROUGH A CHANNEL over time

Question 17

What are the two states that channel is can be in ?

Answer 17

“Gated”—>open/closed or they could be …. Always Open (leak channel)

Question 18

When is sodium channels opens, when does sodium stop entering the cell?

Answer 18

Sodium will stop entering the cell when the positive charge build up inside the cell is equal to the concentration gradient. So in other words, when The force of the positive charge/electrical gradient pushing sodium out is equal and opposite to the force of the concentration gradient pushing sodium in. (that is the equilibrium potential)

Question 19

GHK equation

Answer 19