The heart

• What is one of the functions of the circulatory system in humans?

  To transport substances
• What are the main components of the circulatory system?

  • The heart
  • Blood vessels
  • Blood
• What is the heart classified as?

  A muscular organ
• How many chambers does the heart have?

  Four chambers
• What are the upper chambers of the heart called?

  Atria
• What are the lower chambers of the heart called?

  Ventricles
• What prevents blood from flowing back into the atria?

  Heart valves
• What is the main artery that carries oxygenated blood from the heart?

  The aorta
• What does the pulmonary artery carry?

  Deoxygenated blood to the lungs
• What is the double circulatory system in humans?

  • Two circuits: pulmonary and systemic
  • Pulmonary circulation: blood to the lungs
  • Systemic circulation: blood to the rest of the body
• What happens to oxygen in the lungs during pulmonary circulation?

  Oxygen diffuses into the blood
• What is the role of carbon dioxide in the lungs?

  It diffuses from the blood into the lungs
• What does the systemic circulation transport away from cells?

  Carbon dioxide and other wastes
• Why is systemic circulation under high pressure?

  To deliver blood to the extremities of the body
• Why is pulmonary circulation under lower pressure?

  Because it delivers blood to the lungs only
• How does blood pass through the heart during circulation?

  It passes through the heart twice in one complete circulation
• Describe the sequence of blood flow through the heart.

  1. Deoxygenated blood enters the right atrium
  2. Blood moves to the right ventricle
  3. Blood is pumped to the lungs via the pulmonary artery
  4. Oxygenated blood returns to the left atrium
  5. Blood moves to the left ventricle
  6. Blood is pumped to the body via the aorta
• What happens to the atria and ventricles during contraction?

  They contract in unison
• What is the significance of blood being delivered to the body while also being transported to the lungs?

  It allows for oxygen pickup from the lungs while delivering blood