write the difference between single and double circulation?why is double circulation is necessary in human beings?
single criculation means when the blood reaches one time to the heart in one cycle
and in double circulation the blood is brought to herat two times in the cycle once oxgenated and once deoxygenated
humans have to have duoble circulation so that the oxygenated and deoxygenated bloods are seperated and do not mix with each other
1. Occurrence: Found in only fishes.
2. Mode of circulation: Blood passes only once through the heart to supply once to the body.
3. Nature of blood: Only venous blood passes through the heart.
4. Efficiency: Less efficient as gill capillaries slow down the blood flow so the body receives blood at a low pressure which decreases the rate of oxygen supply to the cells.
1. Occurrence: Found in amphibians, reptiles, birds and mammals.
2. Mode of circulation: Blood passes twice through the heart to supply once to the body.
3. Nature of blood: Mixed or oxygenated or venous blood passes through heart.
4. Efficiency: More efficient as blood flows at higher pressure, especially in birds and mammals, which increases the rate of food and oxygen supply to the cell and also rapid removal of wastes from them.
You might be familiar with the circulation of blood. Now look at this image, this image is a schematic representation of blood circulation.
Here you can observe that the blood passes through the heart twice. Since the blood goes twice through the heart, it is known as double circulation. Warm-blooded animals like mammals have this type of blood circulation.