biology 3 chapter 2.1

The circulatory system and the heart

• The double circulation system in humans consists of blood vessels, blood and the heart.
• The heart is organ that pumps blood around the body 
• Valves prevent backflow of blood 
• CHAMBERS AND MAIN BLOOD VESSELS
• VEINS-ATRIA-VENTRICLES-ARTERIES

Keeping the blood flowing

• Arteries, veins and capillaries are the main type of blood vessels.
• Substances diffuse between the blood and the cells in the…