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. What is a 'Blue Collar'. A blue collar is a working-class person historically defined by hourly rates of pay and manual labor. A blue collar worker refers to the fact that most manual laborers at the turn of the century wore blue shirts, which could hold a little dirt around the collar without standing out.