The following steps are involved in muscle contraction: (1) The sequence of events leading to contraction is initiated somewhere in the central nervous system, either as voluntary activity from the brain or as reflex activity from the spinal cord.
The average Mexican man weighs 165 pounds and stands 5 feet 4 1/2 inches tall, while the median figures for Mexican women are 151 pounds and 5 feet 2 inches, according to a study released by a group representing Mexico's clothing industry.
In Mexico City the average annual temperature varies from approximately 12Â°C to 16Â°C, depending primarily on elevation. Winter falls from December to February and this is when the lowest temperatures are experiences, reaching as low as -5Â°C.