Gas Exchange (Core)


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For the IB Biology course.

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Gas Exchange (Core)

  1. 1. Gas Exchange (Core) Stephen Taylor
  2. 2. Assessment Statements Obj. 6.4.1 Distinguish between ventilation, respiration and gas exchange. 2 6.4.2 Explain the need for a ventilation system. 3 6.4.3 Describe the features of alveoli that adapt them to gas exchange. 2 Draw and label a diagram of the ventilation system, including trachea, lungs, 6.4.4 1 bronchi, bronchioles and alveoli. Explain the mechanism of ventilation of the lungs, in terms of volume and pressure 6.4.5 changes caused by the internal and external intercostal muscles, the diaphragm and 3 abdominal muscles. What connections can you make with other topics? Gas ExchangeCommand terms: Assessment statements from: Online IB Biology Subject Guide
  3. 3. MrT says… I pity the fool who thinks breathing is respiration.
  4. 4. Why do we need a ventilation system? We are large organisms. Oxygen cannot diffuse into all our cells directly from the air, nor can waste products be directly ejected from the body. We have specialised organ systems, which are efficient, but need delivery of nutrients and removal of waste. The ventilation system ensures the blood can be the medium for this. We are land-borne. Gases need moist surfaces (membranes) in order to diffuse. Our lungs are moist membranes, allowing oxygen to diffuse into the blood and carbon dioxide to diffuse out. The ventilation system maintains a large concentration gradient between the alveoli and the blood. The constant flow of past the alveoli brings blood with a high CO2 concentration and low O2 concentration. Breathing out keeps the CO2 concentration in the alveoli low, so it diffuses out of the blood. Breathing in keeps O2 concentration in the alveoli high, so it diffuses into the blood.Diagram from:
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  7. 7. Which process(es) of membrane transport are being used ingas exchange at the membranes of the alveoli?
  8. 8. Breathing Exercises – desk yoga(it’s IBDP after all, let’s bust some stress)1. Simple exercises. Keep your neck straight. • Rotate shoulders forwards, then backwards, 5 times each. • Bend your neck to touch your head to your shoulder, left then right, 5 times each. • Tilt your head forward, touching chest, then backward, 5 times each.2. Breathing observation • Close your eyes, breathe normally. • “Observe” the breathing process.3. Pranayama • Stand up. • Take gentle, deep breaths. • Feel the air moving in and out, trying to control its flow. • Think happy thoughts about graduation. Breathing exercises from: Image: 11,750 Foot Yoga Moment Found on
  9. 9. @IBiologyStephen Please consider a donation to charity via Biology4Good. Click here for more information about Biology4Good charity donations.This is a Creative Commons presentation. It may be linked and embedded but not sold or re-hosted.