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ELEMENTARY PHYSIOLOGY 



QUESTIONS ON LESSON XXI. 



1. Describe the appearance of the corpuscles of the blood as seen with the 



aid of a microscope. How do the red corpuscles differ from the white ? 



2. Describe the changes which take place when a vessel of freshly-drawn 



blood is left exposed to air. 



3. What are the materials dissolved in the fluid part of the blood ? 



4. Describe an experiment by which you would deprive blood of its fibrin. 



5. What is clot ? Of what is it composed ? 



6. What is meant by defibrinated blood ? Illustrate your answer by an 



experiment. 



7. What is meant by the term ' buffy coat ' as applied to blood ? Under 



what circumstances is it formed ? 



8. How would you convert venous into arterial blood ? Where does this 



change take place in the body ? 



9. What are the differences between arterial and venous blood ? 



10. Where and how, in the body, is arterial blood changed into venous ? 



11. What is the cause of the high temperature of the body ? By what means 



is the temperature uniformly distributed ? 



12. Mention some of the chief uses of the blood. 



LESSON XXII. 

 THE HEART AND ITS DISSECTION. 



THE heart is a hollow muscular organ 

 which, by its contraction, forces the 

 blood through the whole system of 

 blood-vessels. A general description 

 of this organ has already been given 

 in Lesson XII., and we shall now pro- 

 ceed to study its structure and action. 

 The student is strongly recom- 

 mended to procure a sheep's heart 

 from the butcher, and dissect it with 

 the help of the simple instructions 

 here given. 



Many of the sheep's hearts sold have a 

 deep cut on the front. This is made on 

 opening the carcase of the animal, while 

 Fig. 113. The Sheep's Heart, carelessly chopping through the breast-bone. 

 viewed from behind. Select one which is free from this defect, and 



i, right ventricle ; 2, left ventricle ; one in which the blood-vessels at the base 

 3, right auricle ; 4, a small portion (upper and broader portion) are not closely 

 cu t. If a superabundance of fat surrounds 

 the base of the heart, remove the greater por- 

 tion of it Without cutting any of the vessels. 



, 

 of the left auricle ; 5. the aorta ; 



inferior ; 9, vena cava superior. 



