What Is Intercellular Fluid And What Is Its Composition?

What Is Intercellular Fluid And What Is Its Composition?

Intracellular Fluid: What Is It?

Inside and outside of human cells, fluids are present. It is estimated that the water within the cell makes up about 42% of its weight. Intracellular fluid is the fluid within cells. A semipermeable membrane that surrounds the cell separates the extracellular fluid from the intracellular fluid.

A cell’s intracellular fluid (ICF) is contained within the cells, divided by the cell membrane. Separate compartments are also formed by the cell membrane within the cell, and these compartments are called organelles. The cytosol is the fluid inside the cell that is surrounded by the cell membrane. Cellular water makes up most of the cytosol. The cytosol contains 70 percent water.

Therefore, the cytosol has a pH of 7.0-7.4. Ion concentrations in the cytosol are lower compared to those in its external environment. The cytosol contains a higher concentration of potassium and magnesium than the external environment of the cell. Low calcium ion concentrations in the cytosol allow signal transduction to occur.

The cytosol dissolves many proteins. Microtubules, microfilaments, and intermediate filaments constitute the cytoskeleton and include proteins such as microtubules, microfilaments, and intermediate filaments.

Extracellular fluid is all the fluid that is outside of the cell. By allowing fluids to move in and out, but preventing unwanted molecules or materials from getting inside, this membrane allows fluids to flow freely.

abnormal accumulation of fluid in the intercellular spaces is
abnormal accumulation of fluid in the intercellular spaces is

Intracellular Fluid Composition

In the extracellular fluid, there is water and dissolved solutes as well as proteins. In addition to solutes, electrolytes are also important for the proper functioning of the human body. When dissolved in a liquid, an electrolyte is an element or compound that produces ions when they are dissolved.

In the cell, as well as electrolytes, there are also several others. However, potassium, magnesium, and phosphate are the ones with the highest concentration.

Extracellular Fluid: What Is It?

All fluids outside the cell are defined as extracellular fluid (ECF). The main components of ECF are tissue fluid and plasma. In the extracellular fluid is also found cerebrospinal fluid, which is found in the cavities of the brain and spinal cord.

In extracellular fluid, sodium ions are more prevalent and potassium ions are less prevalent than in intracellular fluid. Extracellular fluid is secreted from cells within different tissues to maintain a constant cellular environment, which makes those tissues function more efficiently.

Extracellular fluids have a volume of approximately 15 liters; tissue fluids comprise 12 liters and plasma 3 liters. An extracellular matrix (ECM) consists of the fluid suspensions that surround each tissue.

Intracellular Fluid VS Extracellular Fluid

Fluids Are Classified As Intracellular And Extracellular Based On Their Position Relative To The Cell Membrane.

In Contrast To Extracellular Fluid, Intracellular Fluid Refers To All Of The Fluid Outside The Cell, Whereas Extracellular Fluid Describes Everything Inside The Cell.

In Addition To The Cytosol, The Intracellular Fluid Also Contains Proteins, Organelles, And Ions. Transcellular Fluid, Extracellular Matrix (ECM), And Extracellular Matrix (ECM) Constitute Extracellular Fluid.

Intracellular Fluid & Extracellular Fluid Similarities

  • In addition to intracellular fluid, extracellular fluid makes up the body’s total fluid volume.
  • Intercellular fluid exchanges material with extracellular fluid via the cell membrane.
  • A major role of extracellular and intracellular fluids is to support nutrient uptake by cells within the body and to maintain lubrication within the body cavities.

Body Fluid Composition

There are more similarities between the plasma and IF a component of the ECF than either has with the ICF. The plasma of a human has high sodium, chloride, and bicarbonate concentrations. Salt, chloride, and bicarbonate concentrations are high in the IF, but protein is low.

Contrary to the ICF, the ICF contains elevated levels of potassium, phosphate, magnesium, and protein. Potassium and phosphate concentrations are high in the ICF (HPO2/4​​ ), with considerable sodium and chloride concentrations in the plasma and ECF.

Bodies are composed mostly of neutral fluids. As a result, positive ions are balanced by negative ions in fluids. According to the previous figure, sodium (Na+) ions and chloride (Cl-) ions are present inside cells while potassium (K+) ions are seen in the extracellular space of the body.

Sodium and potassium can permeate (leak) through the cell membranes, respectively, but sodium-potassium pumps inside the ICF maintain the high levels of potassium and low levels of sodium in the cell. The pumps remove sodium from the cell and introduce potassium into the cell by utilizing the energy provided by ATP.

Flow Of Fluid Between Compartments

Fluids move between compartments due to hydrostatic pressure. By the pumping action of the heart, blood exerts hydrostatic pressure on the walls of blood vessels. Capillary hydrostatic pressure (also known as capillary blood pressure) represents the higher pressure than that of the opposing “colloid osmotic pressure” in blood.

The constant pressure from circulating albumin at the arteriolar end. Plasma and nutrients are forced into surrounding tissues under this pressure. A venule or a capillary reaches the capillary by collecting fluid and cellular wastes in the tissue. The plasma in the blood is pushed into the IF surrounding the tissues by filter pressure. Subclavian veins carry re-entry of excess fluid in the interstitial space into the vascular system at membranes that are not returned directly to capillaries.

Water movement in the kidney nephrons is especially important for proper urine formation. Capillaries leave more water as hydrostatic pressure increases in the kidneys, causing more urine filtrate to form. Hydration may reduce renal hydrostatic pressure, which reduces nitrogenous waste removal and renal function. If dehydrated, kidneys may fail.

Osmolality gradients determine the flow. Semipermeable membranes produce osmotic gradients when the concentrations of solutes spread across them. Osmotic gradients are ultimately determined by differences in solute concentrations on either side of the membrane.

A membrane moves water from the high concentration to the low concentration part of the membrane by osmosis. Between the IF and plasma (and reverse) and between the IF and ICF (and reverse). Water moves into and out of fluid compartments in every part of the body when conditions change.


You are mostly made up of water. Solutes make up body fluids. Water and solute concentrations must be balanced. Cell function is impaired by a concentrated cytosol. An excessively dilute cytosol can damage and burst cells.

Water moves between compartments using hydrostatic pressure. The cytosol is also osmotically regulated. In some compartments, solutes are transferred actively. It depends on the ability of ions and molecules to pass through an isolated membrane and the presence of concentration gradients.

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