Examples of homeostasis include the regulation of body temperature, the pH of extracellular fluid, or the concentrations of sodium, potassium and calcium ions as well as that of glucose in the blood plasma, despite changes in the environment, diet, or level of activity.
Blue-collar workers perform labor jobs and typically work with their hands. The skills necessary for blue-collar work vary by occupation. Some blue-collar occupations require highly skilled personnel who are formally trained and certified.
In the United States as a whole, there are almost as many immigrants in white-collar jobs (46 percent) as in all other occupations combined. In some states, more than half are in white-collar jobs. However, not all white-collar jobs pay well, and the share of U.S.-born workers in white-collar jobs is even higher.