The outlines of anatomy, physiology, and hygiene Being an edition of The essentials of anatomy, physiology, and hygiene, rev to conform to the legislation making the effects of alcohol and other narcotics upon the human system a mandatory study in public schools . o pre-vent it, the valves would not only be pressed back- THE HEART, 153 ward toward the auricle when the ventricle con^tracted, so as to meet at their edges and close theopening, but, on account of their flexibility, theirborders would be bent still farther back, so as toopen into the auricle, and allow a reflux of bloodinto that ca
The outlines of anatomy, physiology, and hygiene Being an edition of The essentials of anatomy, physiology, and hygiene, rev to conform to the legislation making the effects of alcohol and other narcotics upon the human system a mandatory study in public schools . o pre-vent it, the valves would not only be pressed back- THE HEART, 153 ward toward the auricle when the ventricle con^tracted, so as to meet at their edges and close theopening, but, on account of their flexibility, theirborders would be bent still farther back, so as toopen into the auricle, and allow a reflux of bloodinto that cavity. This difihculty is obviated in the following man-ner : There are numerous fine but strong fibrousthreads or cords attached to the edges of the valves,and from that point running downward to the wallsof the ventricle. These cords are just long enoughto allow the valves to close perfectly, but not passany farther back toward the auricle. But here an-other difficulty arises. If the cords are long enoughto allow the valves to close at the beginning of thecontraction of the ventricle when the cavity is atits full size, then they will be too long when thecontraction is toward its end and the cavity is di-minished in size, and allow the valves to be pressed. Ftg. 43.—Illustrating the action of the valves in the right side of the heart:. 154 ORGANS OF REPAIR. too far back. In other words, to fulfill their object,these cords must be able to become longer or short-
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