The following points highlight the two types of fluids in human body. The types are: 1. Intracellular Fluid 2. Extracellular Fluid.
Type # 1. Intracellular Fluid (ICF):
The fluid of each cell contains its individual mixture of different constituents, but the concentrations of these substances are similar from one cell to another. The composition of cell fluids is remarkable, similar even in different animals, ranging from the micro-organisms to humans.
Important Constituents of the Intracellular Fluid:
The intracellular fluid contains large amounts of potassium and phosphate ions and proteins. It contains moderate quantities of magnesium and sulphate ions. The intracellular fluid contains only small quantities of sodium and chloride ions and almost no calcium ions.
Type # 2. Extracellular Fluid (ECF):
Extracellular fluid includes the following:
(i) Interstitial fluid (= tissue fluid):
It is present in between the tissues. Interstitial fluid resembles sea water.
(ii) Blood Plasma:
It is found in the blood.
(iii) Lymph Plasma:
It is present the lymph.
(iv) Cerebrospinal Fluid (CSF):
It is present inside the ventricles of the brain, the central canal of the spinal cord and in the subarachnoid space around the brain and spinal cord.
(v) Intraocular Fluid:
This fluid is found in the eye ball, e.g., aqueous humour and vitreous humour.
(vi) Serous Fluid:
Intra pleural fluid, pericardial fluid and peritoneal fluid are examples of serous fluid.
(vii) Synovial Fluid:
It is present in the joints.
(viii) Digestive Fluid:
Digestive juices are the examples of digestive fluid.
(ix) Fluid in Urinary Tract:
This fluid is present in the tract of excretory system.
Important Constituents of the Extracellular Fluid:
The extracellular fluid contains large amounts of sodium and chloride ions, reasonably large amounts of bicarbonate ions but only small quantities of potassium, calcium, magnesium, phosphate and organic acid ions are present.
The composition of extracellular fluid is carefully regulated by various mechanisms but especially by the kidneys. This allows the cells to remain continually bathed in a fluid that contains the proper concentration of electrolytes and nutrients for proper cell function.
Trans cellular Fluid:
It is a specialized type of extracellular fluid. The trans cellular fluid is in relatively small amount. Examples: cerebrospinal fluid, intraocular fluid, synovial fluid, etc..