The circulatory system:

• There are three parts: the blood, the blood vessels and the heart.
• Our double circulatory system has two loops:

  Which letters represent the movement of deoxygenated blood?

  A and C.

  
• Name the chamber labelled A on the diagram:

  right atrium

  
• On each side of the heart, the atrium and ventricle are separated by a valve, which prevents the blood from flowing backwards.
• What is the name of the chamber labelled A on the diagram?

  Left ventricle.

  
• The left ventricle has thicker walls because it has to pump blood all the way around the body.
• Which blood vessel carries deoxygenated blood from the heart to the lungs?

  Pulmonary artery.
• The journey of the blood around the body:

  1. Body tissues
  2. Vena cava
  3. Right atrium
  4. Right ventricle
  5. Pulmonary artery
  6. Lungs
  7. Pulmonary vein
  8. Left atrium
  9. Left ventricle
  10. Aorta
  11. Body tissues
• Which blood vessel carries oxygenated blood from the heart to the body?

  Aorta.
• The movement of blood between the ventricles and atria:

  The walls of the atria contact, pushing blood into the relaxed ventricles. The walls of ventricles contract, pushing blood out of the heart. At the same time, more blood will enter the now-relaxed atria. The cycle repeats.
• Pacemakers cells are found in which chamber of the heart?

  Right atrium.
• What do arteries do? 


  They carry blood away from the heart.
• What do veins do? 


  They carry blood towards the heart.
• The coronary arteries supply the heart muscle with oxygen and nutrients.
• Arteries carry blood away from the heart.
• Capillaries carry blood through the body tissues, allowing oxygen, nutrients, and waste products, to be exchanged between tissues and the blood.
• Veins carry blood towards the heart.
• What is the primary function of arteries?

  To carry blood at a very high pressure
• What is a key structural feature of artery walls?

  They have a thick middle layer containing muscle and elastic tissue
• How does muscle tissue in arteries contribute to their function?

  It provides strength and allows the arteries to direct blood flow
• What role does elastic tissue play in arteries?

  It allows the arteries to stretch and recoil
• How does the lumen of arteries compare to their walls?

  Arteries have a relatively narrow lumen compared to their walls
• Why is the narrow lumen of arteries important?

  It keeps the blood pressure high
• What are the main structural components of arteries and their functions?

  • Thick middle layer: Contains muscle and elastic tissue
  • Muscle tissue: Provides strength and directs blood flow
  • Elastic tissue: Allows stretching and recoiling
  • Narrow lumen: Maintains high blood pressure
• What are the smallest blood vessels in the human body?

  Capillaries
• What is the primary role of capillaries?

  To exchange nutrients and waste products with the tissues
• What does it mean that capillary walls are permeable?

  It means substances can move through them
• Why is the thickness of capillary walls significant?

  Because they are only one cell thick, allowing for short diffusion distances
• How does the pressure of blood in capillaries compare to that in arteries?

  Capillaries carry blood at a low pressure
• What is the flow rate of blood in capillaries compared to arteries?

  Capillaries have a lower rate of flow than arteries
• Nutrients that are exchanged between the blood in the capillaries and the body tissues: 


  Glucose and amino acids.
• Waste products that are exchanged between the blood in the capillaries, and the body tissues: 


  Carbon dioxide and urea.
• What is the primary role of veins in the circulatory system?

  To carry blood from the body back to the heart
• How do the size and structure of veins compare to arteries?

  Veins are similar in size to arteries but have thinner walls and a wider lumen
• Why do veins have relatively thin walls?

  Because they carry blood at a much lower pressure
• What feature do veins contain to prevent blood from flowing backwards?

  Valves
• What are the key structural characteristics of veins?

  • Relatively thin walls
  • Relatively wide lumen
  • Contain valves to prevent backflow
• Substances that are exchanged between the blood in the capillaries, and the body tissues: 


  Carbon dioxide, urea, glucose and oxygen.
• Which type of blood vessel is marked with an X?

  Artery.

  
• Based on the side of the lumen relative to the whole vessel, which of the blood vessels must be artery? 


  B.