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.
Blue-collar work is often paid hourly wage-labor, although some professionals may be paid by the project or salaried. There is a wide range of payscales for such work depending upon field of specialty and experience.