what is double circulation?

Answer 1

Fish have a 2 chambered heart (atrium and ventricle). Blood passes from the atrium to the ventricle and then to the body. This is called a one way circulation. It was not until the amphibian heart with 3 chambers developed a double circulation. The reptile and mammalian heart improved on the design when the heart contained 2 separate sides. The right side which collected blood from the body and sent it to the lungs for oxygenation, and the left side collecting blood from the lungs and sending it to the body. In the amphibian heart there was only one ventricle pumping blood to the lungs and the body. This caused some mixing of the blood so it was not a true separate double circulation. The reptile heart had a partially divided ventricle allowing for better separation. The mammalian heart completely separated the ventricle into the right and left. Answer number two is incorrect since the pumping sides are backwards.

Answer 2

In double circulation the blood is pumped through the heart twice.
i.e.

one from heart to body- systemic circulation

second from heart to lungs- pulmonary circulation

There are separate sections in the heart for the blood leaving and entering, as opposed to single circulation where the blood only enters the heart once on it's trip through the body.
A double circulatory system is one where the blood travels through the heart twice before returning to the body.

Let's use the example of mammalian heart :
Blood flows from the body into the heart (via the Verna cava). Blood from the heart is pumped through the pulmonary system to the lungs (the left side of the heart pumps to the pulmonary artery).
The blood then travels (via the pulmonary vein) to the heart again (the right side). The heart then pushes the blood up through the aorta and back to the body.

This type of heart is also called as 4 chambered heart or
Pulmonary heart.
This heart is found in Birds and mammals

Reptiles have transition heart (intermediate of single and double circulation) More interesting is that it is structural 3 but functionally 4 chambered

As you can see, the blood passes through the heart twice, but it is necessary for travel to the lungs first (for gas exchange) before distribution to the body.
And both bloods are never mixed in Heart

Fish have a 2 chambered heart (atrium and ventricle). Blood passes from the atrium to the ventricle and then to the body. This is called a one way circulation. It was not until the amphibian heart with 3 chambers developed a double circulation. The reptile and mammalian heart improved on the design when the heart contained 2 separate sides. The right side which collected blood from the body and sent it to the lungs for oxygenation, and the left side collecting blood from the lungs and sending it to the body. In the amphibian heart there was only one ventricle pumping blood to the lungs and the body. This caused some mixing of the blood so it was not a true separate double circulation. The reptile heart had a partially divided ventricle allowing for better separation. The mammalian heart completely separated the ventricle into the right and left. Answer number two is incorrect since the pumping sides are backwards.

Answer 3

Double circulation is where the blood is pumped through the heart twice. There are separate sections in the heart for the blood leaving and entering, as opposed to single circulation where the blood only enters the heart once on it's trip through the body.

Answer 4

A double circulatory system is one where the blood travels through the heart twice before returning to the body. Let's use the human body as an example: Blood flows from the body into the heart (via the vena cava). Blood from the heart is pumped through the pulmonary system to the lungs (the left side of the heart pumps to the pulmonary artery). The blood then travels (via the pulmonary vein) to the heart again (the right side). The heart then pushes the blood up through the aorta and back to the body.

As you can see, the blood passes through the heart twice, but it is necessary for travel to the lungs first (for gas exchange) before distribution to the body.

This should provide you with enough detail:
http://en.wikipedia.org/wiki/Double_circulatory_system

Answer 5

Double circulation is when the blood passes through the heart twice, one time from the lungs to the heart to the body organs and from the body organs to the heart to the lungs.