Question

1. Define electrochemical gradient
2. Describe the electric, chemical, and electrochemical forces that determine Na+ Ion movement
3. Describe the electric, chemical, and electrochemical forces that determine K+ Ion movement
4. Which ion will move faster across the membrane based on its electrochemical gradient?
5. How can the cell change how permeable it is to an ion? (Critical thinking opportunity)
6. Define the chemical gradient
7. How will ions want to move? Down/with or up/against the gradient?
8. What primary active transport is essential to establishing and maintaining the chemical gradient?
9. Discuss the ways Na+ and K+ can move across the membrane.

Answer 1

ELECTROCHEMICAL GRADIENT: It is the potential of a ion that can move across the membrane.It has 2 parts that are (i)Chemical Gradient where there is difference in solute concentrations and (ii)Electrical Gradient where there is difference in charges across a membrane.

FORCES THAT DETERMINE SODIUM MOVEMENT:

• The sodium concentration is higher outside the cell because the sodium increase the negativity inside the cell
• Although the concentration of sodium higher outside the cell, the Cell do not allow the sodium to enter into cell at rest.
• The Chemical Forces acting On Sodium do not allow to enter the cell
• The Electrical forces acting on sodium allow the sodium to enter the cell when there is decrease in negativity inside the cell as soon as the negativity increases sodium channels open and sodium rush out of the cell.
• The Electrochemical Force acting on sodium is through Active sodium and potassium pump here the chages in charges allow and exit the ions based on the membrane potential.Usually 2 sodium ions exits the cell.

FORCES THAT DETERMINE POTASSIUM MOVEMENT:

• The Potassium Concentration is higher inside the cell because it equilibrium potential is equal to resting membrane potential and maintains negativity inside the ceel.
• Despite of the Concentration,The potassium ions moves moderately across the cell membrane even at rest
• The Chemical Forces acting on Potassium try to maintain equilibrium by moving ions in and out of the cell.
• The Electrical Forces acting on Potassium allow the potassium to exit the cell when there is increase in negativity inside the cell.The Exit of potassium ions is seen during depolarisation and Hyperpolarisation.
• The Electrochemical Force acting on potassium is through Active sodium and potassium pump,Usually 3 potassium ions enters the cell to maintain the resting membrane potential.

POTASSIUM ION moves faster across the membane based on its electrochemical gradient, 3 potassium ions enter the cell at a time,the cell membrane is always permeable to potassium to enter and continuous exchange of potassium ions by leak channels.

The Cell Change permeability to the ion is based on the charge inside the cell and maintaining the membrane potential at rest.Here the cell allow the sodium when there is decrease in negativity and when there is increase in negativity it open the channels to exit the sodium and the channel gates remain closed until the there is change in potential.

CHEMICAL GRADIENT: It is the difference in the concentrations of solute in inside and outside environment.

• The Ions move down the gradient when there is low concenentration and high concentration , then the ions move from high to low concentration. This is observed in sodium moving from higher outer concentration to inner lower concentration
• The ions move against the gradient when there is high concentration and low concentration then the ions move from low to high concentration.This is observed in potassium moving from higher inner concentration to lower outer concentration.
• The ions moving with the gradient is seen when there is equal concentration and the ions exchange occurs only to maintain equilibrium.

Active Sodium and potassium pump is the primary active transport is essential in establishing and maintaining the Chemical Gradient. It Maintains Chemical gradient by allowing and exiting the particular number of ions for each ATP Usage. It allows 3 potassium ions to enter the cell and 2 sodium ions to exit the cell.

The Potassium ion moves though potassium leakage channels passively and Active sodium and potassium pump actively by Primary active transport and the sodium moves only though active sodium and potassium pump.