Circulatory system

• The heart is a double pump system
• blood returns to the heart after being oxygenated at the lungs
• The right-hand side of the heart sends blood to the lungs to be oxygenated (and to remove CO2). This is the pulmonary circuit.
• The left-hand side sends blood to the rest of the body - known as the system circuit
• Deoxygenated blood returns to the right of the heart through the vena cava.

  It is then pumped by the right ventricle to the lungs though the pulmonary artery to be oxygenated .

  Oxygenated blood returns to the left of the heart in the pulmonary vein

  It is then pumped by the left ventricle into the aorta

  Arteries branch off the aorta and transfer blood to the organs
• Blood circulation

  
• Cardiac tissue is myogenic. It contracts and relaxes its out stimulation from the nervous system
• The left and right atria and ventricles contract at the same time
• Heart diagram

  
• Heart


  blood in: coronary artery
• muscle

  blood out: coronary vein
• liver


  blood in: hepatic artery / hepatic portal vein
• Liver

  Blood out: hepatic vein
• Kidney


  Blood in: renal artery
• Kidney


  blood out: renal vein
• Large multicellular organisms with a low surface area:volume ratio require a transport system.