Circulatory System

The circulatory system is a system of blood vessels with a pump and valves to ensure one-way flow of blood

Single Circulatory System

• Blood passes through the heart once per complete circuit of the body.
• Oxygen Diffuses info the blood from the gills.
• Oxygen diffuses from the blood to the body cells.

Double Circulatory System

• Most Mammals, birds and some reptiles and amphibians have double circulatory systems.
• Mammals have a double circulatory system, consisting of blood vessels and a heart that pumps blood. Valves ensure blood flows in the right direction.
• Blood passes through the heart twice on one complete circuit of the body.
• Oxygen diffuses into the blood from the lungs.
• Oxygenated blood is carried to all the cells in the body from the left side of the heart.
• Oxygen diffuses from the blood to the body cells.
• Deoxygenated blood is returned to the right side of the heart.
• Deoxygenated blood is then carries to the lungs.

The Double circulatory system is advantageous over single circulation because low-pressure blood is delivered back to the heart in a mammal, raising it’s pressure before being sent off to the rest of the body. In contrast, in a fish, the low-pressure blood continues around the body, resulting in slower delivery of blood.

The Heart