11th Class Biology Body Fluids and Circulation Blood Circulation In Vertebrates

Blood Circulation In Vertebrates

Category : 11th Class

Blood circulation was discovered by William harvey. In case of vertebrates, blood circulation is of closed type, which can be grouped into two categories :

(1) Single circulation                                                                        (2) Double circulation


Differences between single and double circulation


Single circulation

Double circulation


Blood flows only once through the heart in a complete cycle.

Blood flows in two circuit pulmonary and systemic.


Heart pumps only deoxygenated blood, hence called Venous Heart.

Heart pumps both deoxygenated and oxygenated blood to lungs and body respectively, hence called arteriovenous heart.


Blood is oxygenated in gills.

Blood is oxygenated in lungs.


Less efficient as gill capillaries slow down the blood flow. So, the body receives blood at a low pressure which decreases the rate of \[{{O}_{2}}\] supply to the cells i.e. keeps the metabolic rate low.

More efficient as blood flows at higher pressure, especially in birds and mammals, which increases the rate of food and \[{{O}_{2}}\] supply to the cell and also rapid removal of wastes from them i.e. provides a higher metabolic rate.


Found only in fishes, petromyzon.

Found in dipnoi, amphibians, reptiles, birds and mammals.


Double circulation in mammals can be divided into three parts :

(i) Cardiac circulation : The amount of blood present in the heart. Its value is 8%.

(ii) Pulmonary or lesser circulation : The amount of blood present in the surrounding of lungs and pulmonary blood vessels. Its value is 12%.

(iii) Systemic or greater circulation : The amount of blood which circulates in the rest part of the body. Its value is 80%. It can be divided into three parts -

Arterial circulation - 15%

Capillary circulation - 5%

Venous circulation - 60%

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