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
|
S.N. |
Single circulation |
Double circulation |
|
1. |
Blood flows only once through the heart in a complete cycle.
|
Blood flows in two circuit pulmonary and systemic.
|
|
2. |
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. |
|
3. |
Blood is oxygenated in gills. |
Blood is oxygenated in lungs. |
|
4. |
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. |
|
5. |
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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