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.
Next, how long is a football field? According to the NFL rule book, a field is 360 feet, or 120 yards, long. (By the way, did you know that NASAâs International Space Station is about the size of a football field?o letâs do some math. A person driving at 55 m.p.h. would cover 80.7 feet per second. Multiply that by 5 and the person would drive 403 feet over 5 seconds -- or more than the 300 feet or 360 feet length of a football field.