Language
Country/Area
No result found
The Secret of Plasma and Interstitial Fluid: How Do They Work Together to Sustain Life?
In cell biology, extracellular fluid (ECF) refers to all body fluids located outside the cells of any multicellular organism. In healthy adults, total body water accounts for approximately 50% to 60% of body weight (range 45% to 75%), with women and obese people typically having a lower ratio than lean men. Extracellular fluid makes up about one-third of the body's fluid, and the remaining two-thirds is intracellular fluid. The main component of extracellular fluid is the interstitial fluid surrounding the cells, and in animals with a circulatory system, part of this fluid is plasma.
The composition of the extracellular fluid is critical for normal cellular function and is maintained by a variety of homeostatic mechanisms.
Extracellular fluid is mainly composed of interstitial fluid and plasma, which together account for at least 97% of the extracellular fluid, while lymphatic fluid accounts for a small part. The extracellular fluid can be considered to have two components: plasma and lymph, which are used for transport, and the interstitial fluid, which is used for the exchange of water and solutes with the cells. Interstitial fluid is essentially analogous to plasma, with the two having similar composition due to the continuous exchange of water, ions, and small solutes.
Function of interstitial fluid
Interstitial fluid is the fluid between blood vessels and cells. It contains nutrients from capillaries and carries waste products produced by cell metabolism. The composition of this fluid depends on the exchange between cells in the biological tissue and the blood, which means that the composition of interstitial fluid varies in different tissues and different parts of the body.
The role of transfer fluid
Transfer fluid is formed by the transport activities of cells and is the smallest component of the extracellular fluid. These fluids are contained in the spaces within the epithelium, such as cerebrospinal fluid, aqueous humor in the eyes, periarticular fluid and endolymph in the inner ear, joint fluid, etc. The composition of the transfer fluid varies significantly depending on its location.
Extracellular fluid provides a medium for the exchange of substances, which can be achieved through dissolution, mixing and transport.
Promote oxygen exchange
One of the main functions of extracellular fluid is to promote the exchange of molecular oxygen between blood and tissue cells. Because carbon dioxide is about 20 times more soluble in water than oxygen, it can diffuse more easily between cells and blood. However, hydrophobic oxygen has poor solubility in water and prefers to bind to lipid crystalline structures.
Homeostatic Regulation
The internal environment of the extracellular fluid is stabilized through the process of homeostasis. Complex homeostatic mechanisms operate to regulate and maintain a stable composition of the extracellular fluid. There are significant differences in the concentrations of sodium and potassium ions inside and outside the cell membrane. This difference creates the electrical charge of the cell membrane, with the positive charge outside the cell and the negative charge inside.
When cells carry out electrical activities, the potential of the cell membrane and the movement of ions affect various physiological processes.
Interactions among plasma, tissue fluid and lymph
Arterial plasma, interstitial fluid, and lymph interact at the vascular microvascular level. The permeability of capillaries allows water to flow in and out freely, which makes the exchange of substances between interstitial fluid and plasma possible. At the arterial end of the capillaries, blood pressure is higher than the hydrostatic pressure in the tissues, causing water to permeate into the interstitial fluid.
Electrolyte composition
The major cations in extracellular fluid include sodium and potassium, and the major anions include chloride and bicarbonate. Changes in the concentration of these ions directly affect the function of cells, especially in nerves and muscles, and are crucial for the electrophysiological properties of these cells.
In summary, extracellular fluid is the cornerstone of the survival of multicellular organisms. Not only does it provide the environment that cells need, it also maintains the necessary transport of substances between systems in the body. Whether by exchanging oxygen or regulating the concentrations of nutrients, extracellular fluid contributes to the health of the body at every level. Considering the importance of extracellular fluid, we can't help but ask: Can we properly understand and take care of this fundamental element that sustains life?
