RESPIRATION xiii 



oxygenation of the blood in the tissues helps the blood to combine with CO2 and 

 thus partly prevents the pressure of CO2 from rising, 90. — CO2 may be given off 

 in the lungs although the CO2 pressure is lower in the venous blood than in the 

 alveolar air, 91 — Approximate mathematical treatment of the dissociation curve 

 for CO2, 92. — Effect of the CO2 in blood on the dissociation of oxyhaemoglobin 

 in the systemic blood, 94. — The physiological buffers which prevent abrupt rise 

 or fall of CO2 pressure in the respiratory center, 96. — Effects on the alveolar 

 CO2 pressure of holding the breath or forced breathing, 96. — Abruptness of 

 rises or falls of oxygen pressure in the respiratory center, 100. — This abrupt- 

 ness is the cause of periodic breathing when the alveolar oxygen pressure is low, 

 103. — Artificial production of periodic breathing in healthy persons, 103. — 

 Why shortage of oxygen and consequent periodic breathing do not occur nor- 

 mally, 104. — Addendum. Discussion of some recent theories of the carriage of 

 CO2 by blood, 105. — Interchange of acid between plasma and corpuscles, 106. 



CHAPTER VI. The Effects of Want of Oxygen. io8 



Immediate dependence of the body for its oxygen supply on air, 108. — Anox- 

 aemia produced by lowered pressure of oxygen in the air, 10 9. ^Effects, on the 

 breathing, 109. — These effects largely transitory, 109. — Lowering of the thresh- 

 old of alveolar CO2 pressure, but alveolar CO2 pressure still regulates the 

 breathing, no. — Variability of the effects in different individuals, ill". — 

 Death from anoxaemia caused by excessive removal of CO2 from the blood, 112. 

 — Excess of CO2 in the air counteracts the effects of deficiency of oxygen, ii2.> 

 — Mere increase of breathjng does not diminish the anoxaemia, though it dirnih- 

 ishes the cyanosi^7_JJLA)^--Yrhe pecu lia r sympt omsproducedby forced breathing 

 are apparently due mainly to anoxaemia, 115. — Subsidiary effects of CO2 in re- 

 lieving anoxaen3,ia, 117 . — Periodic breathing at high altitudes is caused by 

 anoxaemia^^Li?.- — Effects of anoxaemia on the frequency of breathing, 118. — 

 Effects in causing fatigue of the breathing, 121. — Effects of anoxaemia on the 

 circulation, 121. — Increase in pulse rate is largely transitory, 12 3, ---Cyanosis 

 and anoxaemia not the same thing, 125^— ::^Effects on the nervous system, 125. — 

 Insidious character of these effects, ^5.— -^Effects on muscular power, senses, 

 memory, and powers of judgment, i26T^^^Personal experiences, 128. — Moun- 

 tain sickness and conditions of its production, 128. — Nervous after symptoms 

 following severe anoxaemia, 129. — After effects on heart, J29. — After effects 

 on respiratory center, 130. — Adaptation to want of oxygen, 130. 



CHAPTER VII. The Causes OF Anoxaemia. . .132 



Defective saturation of arterial haemoglobin, 132. — One cause of this is 

 defective distributioji_.pf air in the lungs, 133. — Experimental proof and ex- 

 planation of this, 133.— rEffg cts of holding the breat h, and explanation of the 

 anoxaemia produceoTM^ i . — Cause of difference between clinical Cheyne- Stokes 

 breathing and periodic breathing produced artificially in healthy persons, 141. 

 — Significance of rapid breathing in cases of illness, 142. — Danger of sudden 

 attacks of restricted and rapid breathing, ijL^^^j^auses of anoxaemia in em- 

 physema, bronchitis, and asthma, 145. — Orthopnoea and its causes, 146. — A 

 second cause of arterial anoxaemia is defective pressure of oxygen in the in- 

 spired air, 146. — Immediate effects and after effects, 147. — The percentage 

 saturation of the arterial haemoglobin is lower than corresponds to the oxygen 



