Extracellular fluid: the body's environment

2021-06-11 03:06 PM

Extracellular fluid and blood always exchange with each other by diffusion of fluids and solutes through the walls of capillaries, extracellular fluid containing ions and nutrients, and the medium.

About 60% of the adult body is fluid.

Most of that fluid is inside the cell and is called intracellular fluid.

The remaining about one-third of total body fluid is outside the cells and is called extracellular fluid.

Extracellular fluid is transported throughout the body by the circulatory system, mainly the blood.

Extracellular fluid and blood are always exchanged with each other by diffusion of fluids and solutes through the walls of capillaries.

The extracellular fluid contains ions and nutrients necessary for the body and is the living environment for all cells in the body.

That is also why extracellular fluid is called the body's internal environment or homeostasis.

The basic difference between intracellular and extracellular:

The extracellular fluid contains many Na, Cl, HCO3- and essential nutrients such as oxygen, glucose, fatty acids.

It also contains CO2, which is transported from the cells to the lungs for excretion into the environment.

Other unnecessary products are also excreted in the urine and faeces.

Intracellular fluid has an important difference from the extracellular fluid. For example, the intracellular fluid contains most of the K, Mg, and PO4 instead of the Na and Cl found extracellularly.

The mechanism by which ions are transported across the cell membrane to maintain such constancy is very important and will be discussed in the next chapter.