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.
Detail of collar showing D-rings. In a BDSM context, a collar is a device of any material worn by a person around the neck to indicate their submissive or slave status in a BDSM relationship. A person wearing a collar to symbolize their relationship with another is said to be collared.