QUESTIONS AND ANSWERS 109 



"What morbid and dangerous states of the blood may be connected with 



the suspension of biliary secretion? 



Jaundice, intoxication with the waste products of the biliary 



secretion (cholesterin and lecithin) and the poisonous products in 



the alimentary canal, due to constipation following a lack of the 



stimulating action of bile on peristalsis. 



What is (a) oxyhaemoglobin, (b) methaemoglobin, (c) haematoidin? 



(a) Haemoglobin charged with oxygen. 



(b) A modification of oxyhaemoglobin in which the oxygen is 

 more firmly united than in ordinary oxyhaemoglobin. It occurs 

 pathologically whenever there is a sudden breaking down of the red 

 blood-corpuscles, e.g., as in azoturia. 



(c) A yellow-brown, crystalline, iron-free product, derived from 

 haematin. It is found in old blood clots. 



Heaet 

 What is the influence of the vagus nerve on the heart? What would 

 be the effect on the heart if the vagi nerves were cut? 

 The vagus (pneumogastric) has a restraining or, as it is termed, 

 an inhibitory effect on the heart movements. If cut, the inhibitory 

 action is removed, the heart rate is greatly increased, and the 

 blood-pressure rises. 



Describe the cardiac sounds. 



There are really four cardiac sounds, but, as they occur in pairs, 

 we recognize only two. The first sound is dull, deep, prolonged 

 and louder than the second, which is short, not so deep and not 

 so loud. The two sounds are best reproduced by pronouncing 

 the words "luih dupp." 



What are the cardiac sounds? What causes these sounds? 



See answer to preceding question. 



The first sound is caused by the closing of the auriculoven- 

 tricular valves and the contraction of the muscular fibres. The 

 second sound is due to the closure of the semilunar valves. 



Explain the action of digitalis on the heart. 



It reduces the frequency of the heart-beat and later excites the 

 cardiac muscle to a stronger and prolonged systole. It is a cardiac 

 tonic. 



Define (a) systole, (b) diastole, (c) cardiac cycle. 



(a) Systole is the term applied to the heart's contraction. It 

 occurs synchronously with the first heart sound ; by it, the blood is 

 driven into the aorta and pulmonary artery. 



