Here's a breakdown:
* Intracellular fluid (ICF): This is the fluid found within the cells, making up about 67% of total body water. It contains dissolved substances like ions, proteins, and nutrients.
* Extracellular fluid (ECF): This is the fluid outside of the cells, accounting for about 33% of total body water. It can be further divided into:
* Interstitial fluid: Fluid that surrounds the cells.
* Plasma: The fluid portion of blood.
* Transcellular fluid: Fluids in specialized compartments like cerebrospinal fluid, synovial fluid, etc.
The cell membrane acts as a selective barrier between these two compartments, allowing some substances to pass through while blocking others. This selective permeability is crucial for maintaining the cell's internal environment and carrying out vital functions.
Here are some key characteristics of the cell membrane:
* Phospholipid bilayer: The membrane is composed of two layers of phospholipids with their hydrophilic heads facing outwards and hydrophobic tails facing inwards. This structure creates a barrier that prevents most water-soluble substances from passing through.
* Proteins: Embedded within the membrane are proteins that act as channels, carriers, receptors, and enzymes. They facilitate the movement of specific substances across the membrane.
* Cholesterol: Cholesterol molecules within the membrane help maintain its fluidity and stability.
Overall, the cell membrane is a complex and dynamic structure that plays a vital role in separating the intracellular and extracellular fluid compartments, controlling the flow of substances between them, and ensuring the proper functioning of cells.
