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11th Class Biology Body Fluids and Circulation Types of Circulation

Types of Circulation

Category : 11th Class

Circulatory system in various groups of animals can be classified as follows :

(1) Intracellular circulation : Occurs inside the individual cells where the distribution of substances is through cyclosis of cell cytoplasm. Example – Protozoans.

(2) Extracellular circulation : When the distribution of the substances occurs inside the body through extracellular or intracellular fluids. This is of following types –

(i) Extra organismic circulation : Canal system in porifera, water vascular system in Echinoderms and gastrovascular system in coelenterates.

(ii) Intra-organismic circulation : It involves circulation of body fluids. It is of following types –

(a) Parenchymal circulation : In platyhelminthes, the fluid filled spaces present in the mesodermal parenchyma tissue between body wall and internal organs are used in the distribution of substances.

(b) Coelomic circulation : Coelomic fluid is concerned with the transport of substances. Example – pseudocoelomic fluid in the roundworms and haemolymph in Arthropods.

(c) Blood vascular system : It contains blood and a pumping structure (heart) for circulation of materials inside the body. It is open circulatory system and closed circulatory system.


Differences between open and closed circulatory system


Open circulatory system

Closed circulatory system


In open circulatory system blood flows through large open spaces and channels called lacunae and sinuses among the tissues.

In closed circulatory system blood flows through a closed system of chambers called heart and blood vessels.


Tissues are in direct contact with the blood.

Blood does not come in direct contact with tissue.


Blood flow is very slow and blood has very low pressure.

Blood flow is quite rapid and blood has a high pressure.


Exchange of gases and nutrients takes place directly between blood and tissues.

Nutrients and gases pass through the capillary wall to the tissue fluid from where they are passed on to the tissues.


Less efficient as volume of blood flowing through a tissue cannot be controlled as blood flows out in open space.

More efficient as volume of blood can be regulated by the contraction and relaxation of the smooth muscles of the blood vessels.


Open circulatory system is found in higher invertebrates like most arthropods such as prawn, insects, etc., and in some molluscs (snails, clams, oyster)

Closed circulatory system is found in echinoderms, some molluscs, (squids) annelids and all vertebrates.


Respiratory pigment, if present, is dissolved in plasma; RBCs are not present.

Respiratory pigment is present and may be dissolved in plasma but is usually held in RBCs.


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