544 



VETERINARY PHYSIOLOGY 



If a markedly deficient supply of oxygen is long 

 continued, permanent damage may be done to many 

 important structures, such as the heart and the 

 central nervous system, and the respiratory centre may 

 be so seriously modified that it may fail to act. The early 

 implication of the higher centres in the brain may prevent the 



65 



37 



Fig. 221.— To show the eflfects of altitudes from sea-level to 8U00 metres 

 upon the pressure of oxygen in the alveoli of the lungs — — — 

 and the saturation of the blood with oxygen 



individual from noticing the onset of the symptoms till 

 consciousness is lost. It is therefore most important to 

 administer oxygen as early as possible in such cases. 



B. The Effects of Increased Atmospheric Pressure. — On the other 

 hand, the atmospheric pressure may be enormously increased 

 without any change in the respirations being produced. The 

 haemoglobin will not take up more than a definite amount of 

 oxygen, and any increase is due to the gas dissolved in the plasma. 



