A state of balance between continuing processes is fundamental to life. This condition arises when opposing forces or actions occur at equal rates, resulting in a stable overall state. In biological systems, it signifies a situation where processes such as synthesis and degradation, or movement into and out of a compartment, proceed concurrently but do not lead to a net change in concentration or amount. An example is the constant concentration of glucose in the blood maintained by the balance between glucose production (through food intake and gluconeogenesis) and glucose consumption (by cells and tissues).
This balanced state is crucial for maintaining homeostasis, the ability of an organism to regulate its internal environment despite changes in external conditions. Failure to maintain it can lead to disease or death. The understanding of these balanced biological states has roots in the early development of thermodynamics and physiology, where researchers observed and quantified the consistent internal conditions of living organisms.