The characteristic that separates Y. pestis infection from disease by the other pathogenic Yersinia spp. is the former's ability to cause serious infection of healthy animals. The disease caused by Y. pestis, plague, can take three forms. Bubonic plague occurs following the bite of an infected flea. The inflammation is caused by the uncontrolled growth of the organism. The organism gains access to the circulatory system from the lymphatic system such that the liver becomes infected. Y. pestis reaches high numbers in the liver and spleen. The organism can be recovered from the blood shortly before death. Septicemic plague occurs when the organism can be recovered from blood in the absence of a bubo. Death occurs because of multiple organ failure as a consequence of lipopolysaccharide (LPS) toxicity. Discoloration of the individual, hence the name Black Death, occurs because of hemorrhage and cyanosis as a result of disseminated intravascular coagulation precipitated by LPS intoxication. The last form of the disease, pneumonic plague, is spread by aerosol. This infection results in a fulminate pneumonia followed by spread to deeper organs. Death can occur within 24 hr.
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The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.