SYSTEMIC DEATH.
Systemic life is constituted by those actions which maintain the mutual dependence of the several parts of the organic whole. Such are the functions which provide new matter for the blood, (digestive secretion and absorp tion)—that which effects a chemical change in the blood, (respiration)—that which distri butes it through the orrans arid tissues (cir culation cardiac, arterial, capillary, and venous) —that which removes from the blood effete matters, (excretive secretion)—and that which is intimately connected with all these functions, though we are ignorant of the mode of its operation, viz. the function of nervous matter or innervation. The cessation of these actions, and the consequent solution of connection between the various parts of the body, is sys temic death. With the cessation of the re maining functions, or those which maintain certain relations between the organic body and objects external to it, constituting the animal life of Bichat, and the relative life of others, we have nothing to do in this place. (See SLEEP.) The obstruction of any one of the functions above enumerated must in a longer or shorter space of time bring the others to a termination. But, as the arrest of the circulation acts upon the other functions immediately, while the latter affect one another merely by the inter vention of the former, we may very properly consider the causes of systemic death under the general head of Syncope.
1. Syncope by asphyxia.— We shall not stop to inquire in what manner the suppres sion of respiration arrests the action of the heart, as the question has been very fully and satisfactorily considered in thearticle ASPHYXIA. For the same reason we shall waive the dis cussion of the accidental causes of this state, viz. strangulation, submersion, &c. &c. The diseases which are said to produce death by asphyxia are those in which syncope would not supervene when it does, but for the obstruc tion of the respiration. They are for the most part affections either of the 'respiratory ap paratus itself, or of the brain and spinal mar row ; and it is almost superfluous to add that they prevent the intercourse between the blood and pure air, either by blocking up the air passages, or by stopping those muscular actions which are essential to a change in the contents of the pulmonary tubes and cells. Certain organic diseases of the heart itself are said to produce death by asphyxia. In these cases there is an obstruction to the motion of the blood through the left side of the heart ; and in the majority of them. the asphyxial sym ptoms are not so much the direct effects of the impediment in the heart, as of the intermediate pulmonary affections, some of the most fre quent of which are bronchitis, cedema of the lung, and pulmonary apoplexy. When, how
ever, a person dies suddenly, with asphyxial sytnptoms resulting from an arrest of the circu lation at the left side of the heart, without any intervening derangement in the organs of re spiration, the case ought not to be considered an instance of genuine asphyxia. The ap pearances imitative of this state (we allude more particularly to various phenomena be longincr to venous congestion) are not occa sioned' as in true asphyxia by the stagnation of blood in the extremities of the pulmonary arteries, the consequence of its not being arterialized, but by the obstacle presented to the currents in the trunks of the pul monary yeins by the lesion of the heart. In.brief, the anatomical difference in the two states is, that in the one the pulmonary arte ries only, in the other both these and the pulmonary veins are the seats of congestion ; the physiolooical distinction is that in the former the obc'struction is chemica'1, in the latter mechanical.
2. Syncope by 11C7TOUS lesions.—The various parts of an animal body are bound together by a reciprocity of action, over and above that particular connection which exists between certain organs, and which results from a mu tual subservience of function. In the latter, the association is perceptible in the normal condition of the body, as, for instance, be tween the organs of digestion and those of secretion, or of digestion and sanguifaction, or in the sympathetic actions of the respiratory muscles ; but the other species of connection is only or chiefly observed in morbid con ditions; in other words, it is only when dan ger is threatened to one organ that the others give tokens of their intimacy and of their interest in its well-being. But for our know ledge of the existence of this community of feeling (a. phrase to be taken only in a me taphorical sense), it would be impossible to throw any light upon the fatal consequences of a great number of diseases and injuries. There can be little doubt that in all states of the system it contributes very materially to the production of that individuality which is one of the grand characteristics of org,anic beings, and which becomes more and more obvious as our survey rises to the higher departments of the animal kingdom. There is a manifest in equality in this respect, even among the su perior classes of animals. Many lesions that would be fatal to birds and Mammalia, are comparatively trivial to reptiles, not so much because the injured part is of less importance in the functional arrangements of the latter, as because other parts have less sympathy with it.