The capillary beds make up the greatest cross-sectional area of the cardiovascular system.
In the capillary beds, the actual exchange of materials takes place between the blood and the cells of the body.
Page 2 Filtration Phenomenon
The wall of the capillary consists of a single layer of flat cells.
The minute spaces surrounding the capillaries and the individual cells of the body make up the
tissue space (interstitial/ extracellular space).
Fluid passes from the capillary into the tissue space and carries with it various substances.
Some of this fluid returns to the capillary on the venous side.
Page 3 Capillary Sphincters
The capillary beds are provided with precapillary sphincters that can reduce or completely stop the flow of blood into the capillaries.
At the other end of the capillary bed are postcapillary sphincters; when these close, there is a back pressure and more fluid flows into the tissue space.