Semipermeable membrane

Definition

A semipermeable membrane allows certain molecules or ions to pass through it by diffusion and occasionally specialized processes. It is essential in the regulation of the internal environment of cells.

5 Must Know Facts For Your Next Test

1. Semipermeable membranes are crucial for maintaining cellular homeostasis by controlling the movement of substances in and out of cells.
2. These membranes are selectively permeable, meaning they allow some substances to pass more easily than others.
3. Key biological examples include the cell membrane and various organelle membranes within a cell.
4. The permeability of a semipermeable membrane can be influenced by factors such as molecule size, polarity, and concentration gradients.
5. In pharmacology, understanding how drugs cross semipermeable membranes helps in predicting drug distribution and efficacy.

Review Questions

• What role does a semipermeable membrane play in maintaining cellular homeostasis?
• How does the selective permeability of a semipermeable membrane affect substance movement?
• Why is knowledge about semipermeable membranes important in pharmacology?

Related terms

Diffusion:

The passive movement of molecules from an area of higher concentration to an area of lower concentration.

Osmosis:

The diffusion of water through a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Concentration Gradient: A difference in the concentration of a substance across a space or a membrane.