Introduction:

Some materials like, nutrients, gases, hormones, waste materials  or cells etc,  that prevent the body from disease, need to be transported and these are transported by blood and lymph in all parts of body.

Fluid circulation can occurs in two ways:

Intracellular circulation: In unicellular forms like, paramecium, cytoplasm shows movement in cells called cyclosis, which helps in distribution of food and oxygen in cells.

Extracellular digestion: fluid circulation that takes place outside the cells and transport materials. Example:- Ascaris, human being, etc.