The mitral valve is on the left side of the heart. It lets blood flow from the upper to the lower heart chamber. Mitral valve regurgitation is diagnosed when the mitral valve in the heart does not close well, which causes blood to leak back from the left ventricle into the left atrium. Mitral valve regurgitation forces the heart to work harder to pump extra blood out of the heart.
Measurement of a track. The proper length for a competitive running track is 400 m (1,312.3 ft). Some tracks are not built to this specification, instead some are legacy to imperial distances like 440 yd (402.3 m). Prior to rule changes in 1979, distances in Imperial units were still used in the United States.
One reason for this is that the football fields have different dimensions. A Canadian football field is a little wider than its US counterpart. Their football fields are a 65 yards wide. The length of the Canadian field is 150 yards and the end zones are twenty yards each. Without the endzones, the length is effectively 110 yards. American high schools have slightly different football field dimensions than the NFL. The goal posts of a high school field in the USA are ten feet high.