PRINCIPLES OF PHYSIOLOGY \\^ 



i. How would you define a vitamin? What difficulty is involved in formulating this 

 definition? 



5. Compare the circulatory systems of a proboscis worm, an earthworm and a caterpillar. 



6. Define "partial pressure" and "tension" of a gas. 



7. Contrast direct and indirect respiration. What are the characteristics of an effective 

 respiratory surface? 



8. Discuss briefly the role of hemoglobin in the transport of oxygen and carbon dioxide. 



9. Compare the excretion of nitrogenous wastes in ameba, earthworm, insect and man. 



10. Discuss the advantages and disadvantages of exoskeletons and endoskeletons. 



11. What functions may be served by the skin of an animal? 



12. Compare the processes of ameboid, ciliary and muscular motion. 



13. What is the explanation of the "all-or-none ' response of a motor unit to stimulation? 



14. Describe the sequence of events in a single muscle twitch. 



15. What is meant by tetanus, tonus and oxygen debt? 



16. Compare the transmission of an impulse along a nerve fiber and across a synapse. 



17. Compare the physiologic properties of the two major coordinating systems of verte- 

 brates. To what extent are these present in invertebrates? 



Supplementary Reading 



The subjects and concepts discussed in Chapters 4 and 5 are covered in much greater 

 detail and at a more technical level in L. V. Heilbrunn's An Outline of General Physiol- 

 ogy and P. H. Mitchell's General Physiology. A wealth of information about the physio- 

 logic adaptations of both vertebrate and invertebrate animals is to be found in C. L. 

 Prosser's Comparative Animal Physiology, in B. T. Scheer's Comparative Physiology and 

 in E. B. Baldwin's An Introduction to Comparative Biochemistry. The lectures given in 

 the Phvsiology course at the Marine Biological Laboratory have been collected as Modern 

 Trends in Physiology and Biochemistry, edited by E. S. G. Barron. The papers given in 

 a symposium on certain aspects of comparative neurophysiology have been published as 

 Physiological Triggers, edited by T. H. Bullock. 



