The Heart

• How does air enter the lungs?

  Air passes into the lungs through the trachea.
• What is the pathway of air from the trachea to the lungs?

  Air from the trachea moves to the bronchi, which leads to each lung.
• What are the smaller tubes that bronchi split into called?

  Bronchioles.
• What is the function of alveoli in the lungs?

  Alveoli are air sacs where gaseous exchange occurs.
• What are the key features of alveoli that facilitate gas exchange?

  • Millions of alveoli provide a large surface area.
  • Very thin walls create a short diffusion path.
  • Good blood supply enhances gas exchange.
• Why is it important for oxygen to be rapidly removed from the blood after diffusion?

  It ensures that the concentration gradient is as steep as possible.
• What type of circulatory system does the heart operate in?

  A double circulatory system.
• How does oxygenated blood enter the heart?

  Oxygenated blood enters the heart through the pulmonary vein.
• What happens to oxygenated blood in the heart?

  It goes to the left ventricle, which pumps it through the aorta to the rest of the body.
• How does deoxygenated blood enter the heart?

  Deoxygenated blood enters the heart through the vena cava.
• What is the role of the right ventricle in the heart?

  The right ventricle pumps deoxygenated blood through the pulmonary artery to the lungs.
• What is the function of valves in the heart?

  Valves stop the blood from flowing backwards.
• What controls the natural resting heart rate?

  A group of cells in the right atrium acts as a natural pacemaker.
• What do artificial pacemakers do?

  They produce electrical pulses to regulate a heartbeat.