QUESTIONS AND ANSWERS 115 



Describe the different stages of asphyxia. How does asphyxia cause 

 death? 



First stage : labored breathing, all muscles of respiration being 

 brought into play ; convulsions ; blood-pressure rises. 



Second stage: inspiratory muscles less active; expiratory 

 muscles still powerful ; convulsions cease. 



Third stage: unconsciousness, occasional inspiratory gaspings, 

 mouth open, the pupils dilated, pulse imperceptible, blood-pressure 

 falls. Death occurs from five to six minutes after the beginning of 

 the first stage. 



Asphyxia causes death by creating a deficiency of oxygen and an 

 excess of carbon dioxide in the blood. Carbon dioxide is a poison 

 and affects the cardiac centre in the brain, causing death. 



Give the composition of normal air and state how it supports life. 



By volume. By weight. 



Oxygen 20.96 23.015 



Nitrogen 79.01 76.985 



Carbon dioxide 03 



Normal air supports life by supplying oxygen which it contains 

 in an uncombined state. 



What animals may, with effort, breathe through a broken long bone? 

 Why? 

 Birds, because they have a system of air sacs in the bones which 

 communicate with the lungs. 



Digestion 



Give the different steps in the process of digestion. 



Prehension, mastication, salivation, deglutition, gastric digestion, 

 intestinal digestion, absorption and defecation. 



Give the dental formula for the horse and the ox. 



Horse:lg,c5E^,.P^ 



3-^ 

 3-3, 



— M x-o- Total 40. No canines in mare, total 36. 

 or 



4rA' 



nrr. T 0~^. C 9l9, P^,M.?-^. Total 32. 

 O^- I 4I4 ' 0-0 3-3 3-3 



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