p. 53 | THE HEART AS A MACHINE

Seventh-Day Adventist Publishing Association · Battle Creek, Mich. · Thursday, January 22, 1880

FromThe Advent Review and Sabbath Herald, Vol. 55, No. 4

THE HEART AS A MACHINE.

THE heart is probably the most efficient piece of physical apparatus known. From a purely mechanical point of view it is something like eight times as efficient as the best steam engine. It may be described, mechanically, as little more than a double force pump, furnished with two reservoirs and two pipes of outflow; and the main problem of its action is hydro-dynamical. The left ventricle has a capacity of about three ounces; it beats 75 times a minute; and the work done in overcoming the resistance of the circulating system is equivalent to lifting its charge of blood a little short of ten feet (9.923 ft.). The average weight of the heart is a little under ten ounces (9.39 oz.). The daily work of the left ventricle is, in round numbers, ninety foot-tons; adding the work of the right ventricle, the work of the entire organ is nearly one hundred and twenty-five foot-tons. The hourly work of the heart is accordingly equivalent to lifting itself twenty thousand feet an hour.

An active mountain climber can average 1,000 feet of ascent an hour, or one-twentieth the work of the heart. The prize Alp engine, “Bavaria,” lifted its own weight 2,700 feet an hour, thus demonstrating only one-eighth the efficiency of the heart. Four elements have to be considered in estimating the heart’s work: (1.) the statical pressure of the blood column equal to the animal’s height, which has to be sustained; (2.) the force consumed in overcoming the inertia of the blood-vessels; (3.) the resistance offered by the capillary vessels; (4.) the friction in the heart itself. This, in a state of health, is kept at its minimum by the lubricated serous membrane of the pericardium.—Scientific American.