Heart

• Explain why an increase of carbon monoxide in the air increases heart rate

  Carbon monoxide combines with haemoglobin. Red blood cells carry less oxygen. Blood flow must increase to meet demand.
• Which blood vessel carries blood from the lungs into the heart?

  Left atrium
• Which blood vessels exchange oxygen with heart muscle cells?

  Capillaries
• Which blood vessel carries blood towards the heart?

  Vein
• Which blood vessel carries blood away from the heart?

  Artery
• Why is the human circulatory system known as a "double" circulatory system?

  • Blood passes through the heart twice
  • The left side of the heart pumps blood around the whole body
  • The right side pumps to the lungs
• Describe the structural features of capillaries?

  • One cell thick for diffusion
  • Narrow lumen for larger surface area to volume ratio.
• Which specific blood vessel carries blood to the lungs from the heart?

  Pulmonary artery
• Why is a change in flow rate important during exercise?

  • Muscles need more energy
  • Means need more aerobic respiration to release energy
  • Requires more blood flow = more oxygen/glucose transported to cells for aerobic respiration
  • Leads to more muscle contractions to remove lactic acid
  • Also, increased blood flow is needed to remove CO2 (waste product of aerobic respiration) from cells.
• Describe how the shape and internal cell structure of a red blood cell are adaptations for its function

  • Biconcave shape = large surface area for gas exchange
  • No nucleus = can contain more haemoglobin