. Essentials of biology presented in problems. Biology. B C Three classes of levers. A, a lever of the first class; B, a lever of the second class; C, a lever of the third class. (See text.) A lever of the second class has the fulcrum at one end, and the weight between it and the power; when we rise on our toes, we use this kind of lever. In a le%'er of the third class, the fulcrum is at one end, with the power between it and the weight. This is the kind of lever seen most frequently in the human body. The flexing (drawing up) of the lower leg or the fore- arm is an example of the use of this
. Essentials of biology presented in problems. Biology. B C Three classes of levers. A, a lever of the first class; B, a lever of the second class; C, a lever of the third class. (See text.) A lever of the second class has the fulcrum at one end, and the weight between it and the power; when we rise on our toes, we use this kind of lever. In a le%'er of the third class, the fulcrum is at one end, with the power between it and the weight. This is the kind of lever seen most frequently in the human body. The flexing (drawing up) of the lower leg or the fore- arm is an example of the use of this kind of lever. In such a lever, a wide range of movement is obtained. General Structure and Uses of the Skeleton. — Evidently bones form a framework to which muscles are attached; thus they are used as levers for pur- poses of movement. Second, they give pro- tection to delicate or- gans ; they form a case around the brain and spinal cord; as ribs they protect the or- gans in the body cavity. Third, they give rigidity and form to the body. The skeleton of a dog; a. typical Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hunter, George William, 1873-1948. New York, Cincinnati [etc. ] American Book Company
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbiology, bookyear1911
