Thus for any region within a fluid, in order to achieve static equilibrium, the pressure from the fluid below the region must be greater than the pressure from the fluid above by the weight of the region.For a fluid at rest, the conditions for static equilibrium must be met at any point within the fluid medium.If negative, fluid will tend to enter the capillary (absorption).If positive, fluid will tend to leave the capillary (filtration).To prevent a build up of tissue fluid surrounding the cells in the tissue, the lymphatic system plays a part in the transport of tissue fluid.Extracellular fluid is separated among the various compartments of the body by membranes.Movement of fluid among compartments depends on several variables described by Starling's equation.Using the known properties of a fluid in one condition, we can use the continuity equation to solve for the properties of the same fluid under other conditions.Since the fluid cannot be compressed, the amount of fluid which flows into a surface must equal the amount flowing out of the surface.The equation of continuity applies to any incompressible fluid.where Q is the flow rate, v is the velocity of the fluid, and a is the area of the cross section of the space the fluid is moving through.

The flow rate of a fluid is the volume of fluid which passes through a surface in a given unit of time.Flow Rate and the Equation of Continuity.Functions of epithelial cells include secretion, selective absorption, protection, transcellular transport, and detection of sensation.This also means that all fluids have the property of fluidity.It is best described as a viscoelastic fluid.The distinction between solids and fluid is not entirely obvious.A fluid is a substance that continually deforms (flows) under an applied shear stress.In analyzing the properties of moving fluids, it is necessary to determine the nature of flow of the fluid.Different fluids exhibit different viscous behavior yet, in this analysis, only Newtonian fluids ( fluids with constant velocity independent of applied shear stress) will be considered.The greater the viscosity, the ‘thicker' the fluid and the more the fluid will resist movement.It describes a fluid's internal resistance to movement and can be thought of as a measure of fluid friction.Virtually all moving fluids exhibit viscosity, which is a measure of the resistance of a fluid to flow.Fluid flow velocity effectively describes everything about the motion of a fluid.The magnitude of the fluid flow velocity is the fluid flow speed.Fluid velocity can be affected by the pressure of the fluid, the viscosity of the fluid, and the cross-sectional area of the container in which the fluid is travelling.Fluid dynamics is the study of fluids in motion and corresponding phenomena.Flow velocity and volumetric flow rates are important quantities in fluid dynamics used to quantify motion of a fluid and are interrelated.Transcellular fluid is the portion of total body water contained within epithelial lined spaces.It is the intravascular fluid part of extracellular fluid (all body fluid outside of cells).The extracellular fluid also includes the transcellular fluid making up only about 2.5% of the ECF.The intracellular fluid of the cytosol or intracellular fluid (or cytoplasm) is the fluid found inside cells.The major body fluid compartments include: intracellular fluid and extracellular fluid (plasma, interstitial fluid, and trancellular fluid).Ocular fluid in the eyes contrasts cerebrospinal fluid by containing high concentrations of proteins, including antibodies.Some of the electrolytes present in the transcellular fluid are sodium ions, chloride ions and bicarbonate ions.Due to the varying locations of transcellular fluid, the composition changes dramatically.The concentrations of the other ions in cytosol or intracellular fluid are quite different from those in extracellular fluid.The pH of the intracellular fluid is 7.4.Examples of transcellular fluid in the following topics:

Body fluid compartments transcellular