"It seems to me that the left side of the heart has a great deal more work to do than the right, for the left has to force the blood into the main artery, and all over the body, to the toes, the fingers, the brain: but the right ventricle only has to force it through the lungs that are close by, touch the heart, and it is a short route."
"True, and for this reason, the muscles of the left ventricle, which force the red blood of the great circulation through the main artery, are much more numerous and stronger than those of the right, which has so much less work to perform. It is the powerful contraction of the muscles of the left ventricle, causing the point of the heart to strike the fifth or sixth rib, that creates the throb you can feel; they exert power enough to send all the blood of the body through the heart twenty-three times in an hour."
"I had no idea matters were going ahead inside of me at that rate."
"You must bear in mind that I have described these things separately, but in the order of nature, it is quite another matter. The red blood from the lungs arrives at the left, and the black blood from the veins at the right auricle at the same instant; both auricles contract at once, and force the blood into their respective ventricles; both ventricles contract together and force the blood into the arteries; and thus it goes on in a person of the feeblest pulse; these alternate motions occupy, when in a state of health, but a second; the pulse at your wrist is the throb of the artery, the stroke of the heart. What do you suppose now is the force of that stroke, when the left ventricle contracts?"
"I'm sure I don't know."
"Well, the blood has been known to spurt more than five feet from the artery of the neck (carotid) when first cut. You see, now, why it is so dangerous to wound a large artery: the blood spurts at every stroke of the heart, while in the veins there is no such pressure or direct connection; besides, as the veins are designed not to carry the blood from the heart, but to bring it back, they are also furnished with numerous valves that favor the flow of blood towards the heart, but not from it."
"There is one thing I can't understand. When a man's leg is cut off, all the arteries and veins cut, how does the blood get back to the heart when the ends of the arteries are tied, and there is no communication between them and the veins?"
"By a provision of nature, there are many minute twigs and branches given off by the arteries all along their course, scarcely observable when the circulation is in its normal state, that are connected with veins equally small; those become enlarged by pressure, and renew the connection."
"It seems to me, Mr. Richardson, that the heart is like two pumps in two wells, side by side, only one throws a bigger stream than the other, and with more force."