Heart and blood vessels

• What type of circulatory system do mammals have?

  Double circulatory system
• Why is a double circulatory system beneficial for mammals?

  It allows higher pressure blood flow
• How does returning blood to the heart after oxygenation affect blood flow?

  It increases the rate of blood flow
• What is the role of the heart in the circulatory system?

  It pumps blood around the body
• What prevents backflow of blood in the heart?

  Valves
• What happens when the ventricles contract?

  Blood is pushed into the arteries
• What are the four chambers of the heart?

  Right atrium, left atrium, right ventricle, left ventricle
• What is the function of coronary arteries?

  They supply blood to the heart
• What do capillaries allow for in tissues?

  Exchange of materials
• How are arteries adapted to carry blood?

  They have thick walls and small lumen
• Why do capillaries have thin walls?

  To increase the rate of diffusion
• What is the total cross-sectional area of blood vessels?

  Very large
• What is the role of plasma in blood?

  It transports nutrients and waste
• What shape do red blood cells have?

  Biconcave shape
• Why do red blood cells lack a nucleus?

  To maximize space for haemoglobin
• How does the structure of red blood cells aid their function?

  They are small and flexible for capillaries
• What are the three main types of blood vessels and their functions?

  • Arteries: Carry blood away from the heart
  • Veins: Carry blood to the heart
  • Capillaries: Exchange materials at tissues
• Describe the adaptations of veins for returning blood to the heart.

  • Thinner walls than arteries
  • Larger lumen to facilitate blood flow
  • Valves to prevent backflow
• Explain how capillaries are adapted to their function.

  • Very thin walls (one cell thick)
  • Slow blood flow for substance exchange
  • Networks called capillary beds
• What are the roles of blood in the body?

  • Transport oxygen
  • Carry nutrients and waste products
  • Fight infections
• What is the significance of the total cross-sectional area of blood vessels?

  • Allows slow blood flow in capillaries
  • Ensures sufficient time for substance exchange
  • Maintains lower pressure in the circulatory system