Ventilation refers to the process of moving air in and out of the lungs. Respiration is the cellular process of gas exchange that occurs in the lungs, where oxygen diffuses into the blood and carbon dioxide diffuses out. The ventilation system, which includes the trachea, lungs, bronchi, bronchioles and alveoli, facilitates gas exchange through its features that maximize surface area for diffusion and maintain concentration gradients between the alveoli and blood. The diaphragm, intercostal muscles and abdominal muscles work together to change the volume and pressure of the lungs during breathing to ventilate air in and out.

1. Gas Exchange (Core)
Stephen Taylor
i-Biology.net

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 Exchange
Command terms: http://i-biology.net/ibdpbio/command-terms/ Assessment statements from: Online IB Biology Subject Guide

3. MrT says…
I pity the fool
who thinks
breathing is
respiration.
http://www.last.fm/music/Mr.T/+images/27372765

6. 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: http://www.sciencequiz.net/jcscience/jcbiology/gapfilling/breathingsystem.htm

7. http://highered.mcgraw-
hill.com/sites/0072495855/student_view0/chapter25/animation__gas
_exchange_during_respiration.html

8. http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP15104

10. Which process(es) of membrane transport are being used in
gas exchange at the membranes of the alveoli?
http://www.footprints-science.co.uk/alveoli.htm

16. 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: http://www.healthandyoga.com/html/news/exercise.html
Image: '11,750 Foot Yoga Moment'
http://www.flickr.com/photos/94833286@N00/2838289483 Found on flickrcc.net

17. @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.