Body Fluids and Circulation?

 Blood and Lymph are the two body fluids which constant supply the useful materials and simultaneously remove the waste substances. The main materials that need to transport in the body is gases, nutrients, hormones, waste materials and molecules. Blood and Lymph fluids are used by most of the higher organism. Circulation of blood fluids is also known as circulatory system. 

Fluid is circulate inside the body by Intracellular circulation and Extracellular circulation. 

Intracellular circulation- It occur in unicellular organisms. All the substances are distributed by regular streaming movement. It also brings carbon dioxide and nitrogenous waste near the cell membrane. Paramecium, Amoeba are the example of intracellular circulation. 

Extracellular Circulation- some animals have additional techniques of fluid circulation outside the cell. 

1) Environmental fluid circulation- Some invertebrates have no circulatory fluid. These animal circulate the surrounded water through the cavities in their bodies with the help of flagella. Example is Hydra.

2) Body fluid circulation- The more active animals have higher metabolic rates. They need quick supply of food and oxygen to their tissues. They also need quick removal of waste material and carbon dioxide. According their requirements, they have developed special body fluid which circulate within the body. Their are four main types of body fluid circulation- 

i) Parenchymal Circulation- This type of circulation found in flatworms. There is no body cavity. The space between the body wall and internal organs is occupied with special tissue called parenchyma. It consists of large, irregular cells, the branching processes from which form a network with fluid-filled space in between. Digested food from the intestine diffuses into the parenchymal fluid. Contractions of the body cause irregular movements of this fluid to distribute the food material it contains to the tissue cells. 

ii) Body cavity circulation- this type of circulation occur in roundworms. The internal organ lies in the body fluid called pseudo-coelomic fluid. There are no blood vessels. The body fluid is moved around the viscera by contractions of the body wall for distribution of food material that enter it from the intestine. 

iii) Blood vascular system- this is found in higher invertebrates and all chordates. These animals have specialized circulating fluid that is blood. Blood is pumped by the heart and passed by the blood vessels. 

iv) Lymphatic system- this is occur in all vertebrates. It comprises lymph, special lymphatic capillaries, lymphatic vessels nd lymph nodes.