lungs

• Trachea


  The windpipe that delivers air into the lungs, is C-shaped to allow expansion
• Bronchus


  The two pipes that split from the trachea and take air into the two lungs
• Bronchioles


  Smaller tubes that branch off from the bronchi to deliver air to the alveoli
• Alveoli


  The tiny air sacs in the lungs (around 500 million) that increase the surface area for gas exchange
• Breathing in


  1. Air enters through nose/mouth

  2. Travels down trachea

  3. Splits into bronchi

  4. Reaches alveoli
• Breathing out


  1. Air leaves alveoli

  2. Travels up bronchi

  3. Travels up trachea

  4. Exits nose/mouth
• Trachea is close to the heart

  Allows oxygenated blood to quickly reach the heart to be pumped around the body
• Lungs can inflate greatly with a deep breath
• Dissection showed the structure of the lungs including the trachea, bronchi, bronchioles and alveoli
• The challenge is to describe the structure and function of the lungs, and explain their adaptations
• Structure of the lungs


  1. Trachea

  2. Bronchi

  3. Bronchioles

  4. Alveoli
• Alveoli


  • About 500 million in the lungs
  • Increase the surface area
• Breathing in


  1. Diaphragm flattens

  2. Intercostal muscles contract, ribs move outwards
• Breathing out


  1. Diaphragm relaxes, moves back up

  2. Intercostal muscles relax, ribs move inwards
• Lungs


  • Large surface area
  • Permeable
  • Thin diffusion pathway
  • Moist
• Blood supply to lungs


  • Good blood supply
  • Maintains concentration gradient
• Oxygen goes from alveoli into the blood
• Carbon dioxide goes from the blood into the alveoli
• Exam is Biology Paper 1
• Revision card should be titled "Lungs"
• Things to include on revision card


  • Structure of lungs (trachea, bronchi, bronchioles, alveoli)
  • Breathing in (diaphragm flattens, intercostal muscles contract, ribs move outwards)
  • Breathing out (diaphragm relaxes, intercostal muscles relax, ribs move inwards)
  • Adaptations of lungs (large surface area, permeable, thin diffusion pathway, moist)
  • Blood supply (good blood supply, maintains concentration gradient)
  • Oxygen and carbon dioxide exchange