Effect of Monovalent and Divalent Ions on Membrane Permeability

Monovalent Ions (Na+, K+)
- Monovalent ions have a positive charge and are smaller in size compared to divalent ions.
- They can easily pass through the cell membrane via ion channels and transporters.
- The movement of monovalent ions across the membrane is regulated by the concentration gradient and electrochemical potential.
- When the concentration of monovalent ions is high outside the cell and low inside, they move into the cell, and vice versa.
- The permeability of the membrane to monovalent ions is high, which means they can pass through the membrane easily and quickly.
- Therefore, the presence of monovalent ions increases the membrane permeability.

Divalent Ions (Ca2+)
- Divalent ions have a higher charge and larger size compared to monovalent ions.
- They cannot easily pass through the cell membrane because of their size and charge.
- The movement of divalent ions across the membrane is slower than monovalent ions and is regulated by specific transporters and channels.
- When the concentration of divalent ions is high outside the cell and low inside, they move into the cell, and vice versa.
- The permeability of the membrane to divalent ions is low, which means they cannot pass through the membrane easily and quickly.
- Therefore, the presence of divalent ions decreases the membrane permeability.

Conclusion
In summary, monovalent ions increase the membrane permeability because they can easily pass through the membrane via ion channels and transporters and their movement is regulated by the concentration gradient and electrochemical potential. On the other hand, divalent ions decrease the membrane permeability because they cannot easily pass through the membrane due to their size and charge, and their movement is slower and regulated by specific transporters and channels.