The Lungs and Circulatory Sytem

• Name the tube that split off the trachea:

  Bronchus
• Explain the role that alveoli play in gas exchange

  Oxygen and carbon dioxide exchange.
• Explain why the circulatory system in humans is described as a ‘double circulatory system’?

  Because it consists of two separate circuits: the pulmonary circuit, which carries deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart, and the systemic circuit, which carries oxygenated blood from the heart to the rest of the body and deoxygenated blood back to the heart.
• Why does the heart have valves?

  To prevent backflow of blood.
• Name the four chambers of the heart

  1. Left Atrium
  2. Right Atrium
  3. Left Ventricle
  4. Right Ventricle
• How is resting heart rate controlled in a health heart?

  The pacemaker in the right atrium is a group of cells.

  These cells produce a small electric impulse which causes muscles to contract.
• How are arteries adapted to carry bloody away from the heart?

  Elasticity and muscular walls.
• Why do red blood cells not have a nucleus?

  Red blood cells do not have a nucleus because it allows them to have more space to carry oxygen and increases their flexibility for traveling through narrow blood vessels.