metabolic rate

• fish - single - 2 chambers - 1 ventricle 1 atrium
• amphibians - double - 3 chambers - 2 A, 1 V
• reptile - double - incomplete - 3 chambers - 2 atrium, 1 ventricle
• birds - double - complete - 4 chambers - 2 atria, 2 ventricles
• mammals - double - complete - 4 chambered heart - 2 atrium, 2 ventricles
• single - blood passes through the heart once during each complete circuit of the body
• double - blood passes through heart twice, allowing blood to be pumped to capillaries and other tissues at a higher pressure, ensuring more efficient delivery of oxygen
• complete - 2 ventricles separated by a septum
• incomplete - only one ventricle
• metabolic rate can be measured by

  • Oxygen consumption - respirometers
  • carbon dioxide production - measured using respirometers
  • Heat production – Using calorimeters
• organisms with high metabolic rates

  require a more efficient delivery of oxygen to cells.
• advantage of complete double circulatory systems

  • higher metabolic rates to be maintained.
  • There is no mixing of oxygenated and deoxygenated blood.
  • Oxygenated blood can be pumped out at a higher pressure.
  • This enables more efficient oxygen delivery to the cell.