URINE 557 



If, on the other hand, a condition of alkalosis (p. 531) 

 is produced, NaoHPO^ is excreted — OH ions being elimin- 

 ated. 



Under normal conditions the reaction of the urine varies 

 between Na„HPO^ and NaH.PO^. 



The administration of acids does not materially increase the 

 hydrogen ion concentration. They combine with the sodium 

 of the bicarbonate of the plasma, turn out the CO,, increase 

 the amount of dissolved COo, and thus stimulate the respiratory 

 centre to increase the ventilation of the lungs and then to 

 eliminate the COo and adjust the proportion of — 



H„CO, 1 



NaHCOg 20 



But when alkalies are given, or the citrates, malates, and tartrates 

 of sodium or potassium which are oxidised to carbonates in the 

 body, the kidneys then act in eliminating the increased OH 

 ions and thus readjusting the balance of ions in the blood 

 plasma. 



II. Physical Characters. 



The characters of the urine depend largely on the relative 

 proportion of water and of solids which are excreted in it : at 

 one time it may be very concentrated, while at another time it 

 may be very dilute indeed. For this reason its specific gravity, 

 which depends upon the percentage of solids in solution, varies 

 within wide limits. But the average specific gravity in the 

 horse is about 1036. It is possible from the specific gravity 

 to form a rough idea of the amount of solids present, for by 

 multiplying the last two figures by 2'22 the amount of solids 

 per 1000 parts is given. 



Since the percentage of pigments in the urine varies like 

 that of the other constituents, the colour of the urine shows 

 wide divergence in the normal condition. A concentrated 

 urine has a dark amber colour, while a dilute urine may in 

 some animals be almost colourless. Under average conditions 

 the urine has a straw-yellow colour. 



The reaction of urine is normally acid in dog and other 

 carnivora. 



