National League for Nursing (NLN) Science Practice Exam

Homeostasis refers to the processes and mechanisms that organisms use to maintain a stable internal environment despite changes in external conditions. This involves regulating various physiological parameters such as temperature, pH, hydration, and the concentration of ions, which are crucial for the proper functioning of cells and overall health. For example, when the body temperature rises due to external heat, mechanisms such as sweating and increased blood flow to the skin help cool the body down. Conversely, when the temperature drops, shivering and conservation of heat can help raise the body temperature back to normal levels.

In contrast, the other options describe different biological processes that do not pertain to the concept of homeostasis. Cell division is a process through which cells reproduce; cellular respiration involves the metabolic processes that convert food into energy; and neurotransmitters are chemical messengers that affect communication between neurons. These functions, while essential to biological systems, do not encapsulate the idea of maintaining stability in the internal environment of organisms. Thus, the maintenance of stability in biological systems accurately defines homeostasis.