In the human body, there are two major types of fluid systems, 1- blood system and 2- lymph system. In addition to blood, plasma, lymph, and tissue fluid, there are in the body special fluid systems which perform very specific and specialized functions:
1. Cerebrospinal fluid, also called CSF
2. Ocular fluid
3. Synovial fluid
4. Pleural fluid
5. Pericardial fluid
6. Peritoneal fluid
1. Cerebrospinal Fluid (CSF)
1. The brain and spinal cord are covered by 3 membranes. Between the two inner membranes, there is a space called the subarachnoid space. This space is filled with a fluid called cerebrospinal fluid (CSF).
2. The brain floats in the CSF and is thus protected to some extent from jerks and minor hits to the head.
3. The CSF is being constantly formed, circulated and absorbed.
4. Normally the constituents of blood do not penetrate into the CSF because of a lipid barrier, called the blood-CSF barrier. This is very similar to the lipid layer barrier between the blood and brain tissue fluid, called the blood brain barrier.
2. Intraocular Fluid
1. The eye contains a fluid which is very similar to the CSF. It is called aqueous humor. The aqueous humor is also constantly formed and absorbed.
2. The aqueous humor maintains the correct pressure within the eyeball. If this pressure falls, the eyeball collapses and the person becomes blind.
3. If because of diminished absorption, the pressure of aqueous humor rises, the internal parts of the eye are damaged. This disease is called glaucoma.
3. Peritoneal, Pleural, Pericardial and Synovial Fluid
The main purpose of these different special fluids is to provide lubrication to facilitate the movement of the lungs, intestines, heart and the joints.