Your kidneys are complex organs. They regulate the amount of water lost from the body and get rid of waste products, especially urea. Urea is made when any excess amino acids are broken down in your liver.
Middle Class Income for a Family. The annual average income for a middle class family of four is approximately $70, 354. This is based on a 2006 report by the U.S. Census for a family of four. This figure is in the middle of the range of incomes for this section of the population. The median income during this time for all households was $48,561.
Middle class a matter of income, attitude. CINCINNATI -- Strictly speaking, the median, or middle, household income in the United States today is $50,054. That's easy. The hard part is figuring out how far above or below the middle someone's income can go and still be considered middle class.