Introduction to Organismal Biology (BIOL221) - Dr. S.G. Saupe; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321; ssaupe@csbsju.edu; http://www.employees.csbsju.edu/ssaupe/

Study Guide & Review for Gas Exchange

I. Goal:  The goal of this unit is to provide a basic understanding of the general principles of gas exchange in plants and animals

II. Reading(s):  Chapter 42.4

III.  Objectives:  Upon completion of this unit you should be able to: 

1. Define Fick's law.  Identify how each of the terms in the equation influence gas exchange.
2. Compare and contrast diffusion and bulk flow.
3. Explain why animals use bulk flow to move gases to respiratory surfaces, while plants and a few animals like hydra, use diffusion.
4. A necessary evil of obtaining required gases (carbon dioxide and/or oxygen) is water loss.  Explain how organisms minimize water loss while maximizing gas uptake.
5. Compare and contrast how frogs, fish and humans get gases to their respiratory surfaces.
6. Define partial pressure and explain how it influences diffusion across respiratory surfaces.
7. Describe how the need for circulatory and respiratory systems changes with increasing animal body size.
8. Define gas exchange and distinguish between a respiratory medium and a respiratory surface.
9. Describe the general requirements for a respiratory surface and list a variety of respiratory organs that meet these requirements.
10. Describe respiratory adaptations of aquatic animals.
11. Describe the advantages and disadvantages of water as a respiratory medium.
12. Describe countercurrent exchange in fish gills. Explain why it is more efficient than the concurrent flow of water and blood.
13. Describe the advantages and disadvantages of air as a respiratory medium and explain how insect tracheal systems are adapted for efficient gas exchange in a terrestrial environment.
14. For the human respiratory system, describe the movement of air through air passageways to the alveolus, listing the structures that air must pass through on its journey.
15. Describe the role of surfactants in alveoli.  Explain why the absence of surfactants may lead to respiratory distress in severely premature infants.
16. Compare positive and negative pressure breathing. Explain how respiratory movements in humans ventilate the lungs.
17. Compare the respiratory systems of birds and mammals, explaining the greater efficiency of oxygen exchange in birds.
18. Explain how breathing is controlled in humans.
19. Describe the adaptive advantage of respiratory pigments in circulatory systems.
20. Describe the hemoglobin molecules.
21. Draw the Hb-oxygen dissociation curve, explain the significance of its shape, and explain how the affinity of hemoglobin for oxygen changes with P_O2 and pH.  Explain how it differs between a fetus and mom.
22. Describe how carbon dioxide is picked up at the tissues and carried in the blood.
23. Discuss the advantages and disadvantages of water and of air as respiratory media.
24. Compare and contrast breathing in adult amphibians, birds and mammals.
25. For humans, describe the exchange of gases in the lungs and in tissues.
26. Draw and explain the hemoglobin-oxygen dissociation curve.
27. Draw the two major types of guard cells.  Identify four features common to all guard cells and the function of each.
28. Explain how guard cells mechanically open/close the stoma.
29. Explain the physiology of guard cell action and response to the environment.
30. If a persons lives one mile above sea level in Denver (CO) where teh atmospheric pressure is 630 mm Hg, what is the PO2 of the inspired air?
31. Explain why it is dangerous to voluntarily hyperventilate to lower the arterial PCO2 before going underwater.

IV.  Common Terms/Concepts (can you use the following terms/concepts conversationally?) 

• Bulk flow
• Carbonic anhydrase
• Cellulose microfibril
• Concentration gradient
• Counter current mechanisms
• Diffusion
• Fick�s law
• Negative pressure breathing
• Partial pressure
• Positive pressure breathing
• Ventilation

V. Activities (Some learning activities and tips for studying):

1. Check out the tips in the Plant Structure/Function Study Guide
2. Make a concept map for the unit
3. Be sure to visit the Study Area of the textbook website

VI. Questions: After completing the activities, write any question(s) that you still have concerning the objectives or that pertain to related areas.  Check the text or other sources for the answers.  Or, contact me!

VII. Application: Write one or more ways in which you can immediately apply this information to your daily life.

VIII. Assessment: Meet with one or more members of the class to help assess that you have attained the objective and to help deepen your understanding of the material. Answer the questions at the end of the chapters. Write your own exam questions. Visit the text book web site.