BLOOD I'RESSVRE MODEL 



SSi'S 



Open e to a and force the fluid out into a collecting jar. Tlie a]>[)aratus is 

 now ready for another determination. 



{d) Micro appamfua (Fig. 113). This apparatus is easier to iuaiii|)ulate, and 

 as water, etc., never enters the gas pipette, it is easily kept clean. The 

 different parts are in the same relative pro{)ortions as the corresponding 

 parts of the larger apparatus. Each division of U-U02 c.c. on the smaller 

 corresponds to 0-01 c.c. on the larger. 



(1) It is advisable to mark the course of the canals with pencil on the 

 butt end of the tap d. 



(2) No froth preventer is necessary or advisable. It merely acts on the 

 tap lubricant. 



(3) All quantities are reduced to 1/5 of those given above, e.g. 0-2 c.c. 

 plasma, 0-1 c.c. water, and 0-1 c.c. acid. In all, exactly 0-5 c.c. of Huid is 

 used. 



Calculation of Results. 



Table for Calculation of CO2-C0MBINIXG Power of Plasma 

 (from Van Slyke and Cullen). 



Intermediate values may be obtained by interpolation. 



B = observed barometric pressure. 



Normal range — adult 53-77 c.c, infants about 10 per cent, lower. 



71. Blood Pressure Model. 



(a) Goieral distribution. Examine the schema (Fig. 114) of the circulation 

 given you and identify the parts representing arteries, capillaries and veins. 

 Disconnect the rubber ball H and the two Bunsen valves V, V. Attach 

 the arterial tube A to the water supply and lead the tube from G to the 

 sink. Cautiously turn on the water and measure the pressure in the arteries 

 (at B), and in the veins (at E). (It is more economical to have single vertical 

 tubes at B and E, the pressures read of¥ in millimetres of water may be 

 calculated in millimetres of mercury.) 



Note the effect of (a) varying the force of inflow* by manipulation of the 

 water tap, (b) varying the resistance to flow by tightening the clip at D. 

 With a steady pressure over its whole length, compress G and note alteration 

 in manometer levels. 



(6) Pulse. Fill with water and replace H and V-V in circuit. Gently 

 compress and relax H at regular rhythmic intervals of about a second. Note 



