Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 2: Dia-Ins
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit25760/616/
HEART. 
008 
Ilarvey and some of the older anatomists ob¬ 
served the movements of the venæ cavæ to 
continue in some of the lower animals after the 
auricles had ceased to move. The apex of the 
ventricles frequently remains longer contractile 
than the rest of the ventricle. Haller suggested 
that this might depend on the remaining blood 
gravitating to the apex, and there acting as a 
stimulant. 
Duration of contractility after death.—In 
the cold-blooded animals the heart may be 
made to contract fourteen, twenty, thirty-four 
hours, or even longer after death. In warm¬ 
blooded animals the heart remains contractile 
for a much shorter period after death than in 
cold-blooded animals. Haller found the heart 
contractile in a warm-blooded animal in one 
case four hours after death, and in another 
seven hours. He sometimes observed it to 
cease before the vermicular motion of the intes¬ 
tines. Wepfer found it irritable in a dog six 
hours after death. Nysten, who attended par¬ 
ticularly to this subject, found in one of his 
experiments on the human subject, that the 
ventricles refused to contract upon the applica¬ 
tion of galvanism one hour after decapitation, 
while the auricles continued contractile for 
seven hours five minutes after death.* § In ano¬ 
ther case the right auricle was still contractile 
eight hours after death ;+ and in a subsequent 
case which he relates, it remained contractile in 
the neighbourhood of the entrance of the supe¬ 
rior cava sixteen hours and a half after death.J 
In the Mammifera, Nysten found that the left 
ventricle often refused to contract thirty minutes 
after death ; that the right ventricle retained its 
contractility two hours, and sometimes longer, 
while the right auricle was not quiescent upon 
the application of the galvanism until eight 
hours after death. 
He found it to vary in birds according to the 
degree of muscular activity which they enjoyed 
during life. In those of high flight, and which 
exercise great muscular contractility during life, 
and have a rapid circulation, as the sparrow- 
hawk, the irritability of the heart and other 
muscles becomes much more speedily exhaust¬ 
ed than in those the movements of which are 
comparatively slow and feeble, as in most domes¬ 
tic fowls.§ Nysten supposes that the explana¬ 
tion of the greater persistence of contractility of 
the right ventricle over the left lies in the cir¬ 
cumstance that the left acts with greater vigour 
during life, thus referring it to the important 
general law which he has established by his 
experiments upon the comparative excitability 
of the muscular tissue in the various classes of 
animals, that the duration of the contractility 
after death is in the inverse ratio of the muscu¬ 
lar energy developed during life. || Before we 
* Op. cit. p. 316. 
t Page 318. 
t In these experiments all the other parts of the 
body lost their contractility before the right auricle. 
§ Op. cit. p. 349. 
|| Dr. Marshall Hall (Phil. Trans. 1832) has 
more lately laid it down as a general law that the 
irritability of the heart and other muscles is in the 
inverse ratio of the oxygen consumed in respiration. 
could admit this explanation, it would be ne¬ 
cessary to show, what we believe it will be 
found impossible to do, that the left ventricle, 
apart from its greater quantity of muscular fibre, 
exerts greater strength or exhibits more ener¬ 
getic contractions during life than the right 
ventricle. In young animals, immediately after 
birth, the contractility of the heart continues 
longer after death than in the adult animal. 
We would expect this to be most apparent in 
those which are born with their eyes shut, as 
puppies and kittens, and in those birds which 
are hatched without feathers, since these ani¬ 
mals at that period of life approach in their 
physiological conditions to the cold-blooded 
animals. There is a curious circumstance 
stated by Mangili, and confirmed by Dr. Mar¬ 
shall Hall, connected with the hybernation of 
animals, that if those mammalia which hyber- 
nate are killed while under a state of lethargy, 
the heart and other muscles remain contractile 
for a longer period than when they are killed 
in a state of activity, thus resembling, when 
under the influence of this lethargy, in this as 
in many other respects, the physiological con¬ 
dition of the cold-blooded animals. The con¬ 
tractions of the heart may frequently be renewed 
by the application of warmth after they have 
apparently ceased. I have repeatedly observed 
the fact which has been stated by Haller and 
Nysten, that when any of the cavities of the 
heart become congested with blood, their con¬ 
tractility becomes arrested, and, in their opi¬ 
nion, extinguished.* I have also found that 
unloading the right side of the heart soon after 
the congestion has taken place, which can be 
done in many cases by opening the external 
jugular vein, acts as a valuable adjuvant under 
certain circumstances in renewing the heart’s 
action. These it would be out of place to dis¬ 
cuss here ; but I may state that it appears to 
me to be principally useful in certain cases of 
poisoning, in asphyxia, and after the accidental 
entrance of air into the veins. Since the intro¬ 
duction of a considerable quantity of air into 
the veins produces death by mechanically ar¬ 
resting the movements of the right side of the 
heart, we believe that circumstances may occur 
in which the surgeon may be justified in intro¬ 
ducing a tube into one of the large veins pass¬ 
ing into the upper part of the chest, and suck- 
Various experimenter* distinctly show that as we 
descend in the scale of animals the quantity of oxy¬ 
gen consumed diminishes, and that Birds consume 
more than Mammalia. Dr. Edwards has also 
shown that the young of the Mammalia deteriorate 
the atmospheric air less rapidly than the adult ani¬ 
mals ; and the experiments of Mangili and Prinella 
prove that hybernating animals, when in a state of 
lethargy, consume exceedingly little oxygen, so 
that there is evidently some relation between irri¬ 
tability and the quantity of oxygen consumed in re¬ 
spiration ; but for the proof that the irritability is 
exactly in the inverse ratio of the respiration, we 
must wait for Dr. Marshall Hall’s promised experi¬ 
ments. 
* Haller supposed that this was effected, as must 
be if allowed to continue for any length of time, 
by the too great distension of the muscular fibres, 
in the same manner as distension of the bladder 
produces paralysis of its fibres.
        

Nutzerhinweis

Sehr geehrte Benutzer,

aufgrund der aktuellen Entwicklungen in der Webtechnologie, die im Goobi viewer verwendet wird, unterstützt die Software den von Ihnen verwendeten Browser nicht mehr.

Bitte benutzen Sie einen der folgenden Browser, um diese Seite korrekt darstellen zu können.

Vielen Dank für Ihr Verständnis.