Diffusion and Electrostatics

Question 1

What exists both inside and outside of a neuron?

Answer 1

Ions and other particles, wich are able to move around

Question 2

Many forces guided the behaviour of the ions and particles, name the 2 that are important to us

Answer 2

• diffusive forces
• electrostatic forces

Question 3

The movement of wich ions, across the membrane of a neuron can change its membrane potential?

Answer 3

the movement of charged particles such as K+ and Na+ ions

Answer 4

• diffusion is a process by wich particle spread out or mix, for instance, in a solution
• the process caused particles to move “jiggle” from regions of high concentration to regions of lower concentration

Question 5

How can these forces affect the movement of an ion across a neuron’s membrane?

Question 6

What are electrostatic forces?

Answer 6

the attraction between opposing charges (negative and positive) and the repel between two like charges (positive and positive/negative and negative)

Question 7

What happens during diffusion?

Answer 7

• particles spread out or mix, for instance, in a a solution
• the particles move from regions of higher concentration to lower

Question 8

What serves the basic off all electricity?

Answer 8

The positive or associated charge, particles associat with

Question 9

K+ (potassium) ions are at a high concentration (about 150 mM) inside the neuron and at a low concentration (about 10 mM) outside.

Via diffusion, I would expect:

Answer 9

• K+ ions to move from the inside to the outside of the neuron.
• Explanation: Since K+ has a higher concentration inside of the neuron, it will move down its concentration gradient from the inside to the outside of the cell.

Question 10

At rest, the inside of a neuron is said to be more negative relative to the outside of the neuron (resting potential of about -75 mV). Given a K+ ion (potassium) and based purely on electrostatic forces, I would expect:

Answer 10

-K+ ions to move from the outside to the inside of the neuron.

• Explanation
  The inside of the neuron is more negative, so K+, a positive ion, will be attracted to the inside of the cell and will move from the outside to the inside. Note that this electrostatic movement is opposite the movement we expect, under normal conditions, for K+ ions based on their concentration gradients, as you saw in the previous question. In other words, diffusion and electrostatic forces are opposing each other.