36 



EXEECISEVI 



AETEKIAL-PKESSUKE KECOED ; INFLUENCE OF ADEENAL EXTEACT ; OF 

 ASPHYXIA ; AND OF AMYL NITEITE ; MEASUEEMENT OF VENOUS PEES- 

 SUEE; OCCLUSION OF COEONAEY VESSELS. 



.^.'-A decapitated carcase supplied with pulmonary ventilation is 

 provided as for exerc. IV. See as in exerc. IV that it is in good order. 



II. Set the Ringer-Locke fluid warming and get ready the instruments 

 and apparatus for a kymographic record, and for intravenous injection by 

 the needle-syringe. Get ready also a manometer for observation of venous 

 pressure. This latter manometer contains half-saturated Na2So4 solution 

 instead of Hg, has no float, its junctional tubing is not pressure-tubing, 

 and it has no reservoir-bottle attached to it ; no graphic record is taken 

 by it, so that it need not be brought up to the kymograph, but it should 

 have a paper scale in cm. marked on its mounting for reading the venous 

 pressures by. Have ready glass cannula for insertion into vein. See that 

 you have also at hand (1) adrenal extract, (2) amyl nitrite, (3) a few fine 

 entomological pins. 



III. Operation. Expose one of the carotids (see exerc. V), preferably left, 

 leaving right side free for external jugular vein later ; attach to the artery 

 the Hg manometer, &c., as in last exercise, and obtain an arterial-pressure 

 record by the kymograph as last time. 



Obs. 22. IV. Give an injection of adrenal extract by the saphena vein (see exerc. 



Adrenal extract y\ rpj^^ ^^g^ j^^™ y^^ 1 ^ ^ ^^ ^^iq -01 per cent, solution of adrenalin provided 

 on arterial ./ z a x 



pressure. f^i' jou- It should be injected while the kymograph is running (text-fig. 17). 



Note the resulting rise of arterial pressure. 



Obs. 23. V. Set the kymograph running and after half a minute or so clamp 



Asphyxia and or detach the rubber tube from the respiration-pump to the trachea. 

 Note the resulting disappearance of respiratory undulations from the 

 arterial-pressure record. Observe the colour of the blood in the arterial 

 cannula ; its bright arterial tint will continue for many seconds, and the 

 pressure record will show little further change so long as the scarlet colour 

 in the cannula continues. After a variable but always lengthy period, e.g. 

 100-200 sees., the blood will rather suddenly darken, and then a rise of a. p. 



arterial 

 pressure. 



