What is meant by the term homeostasis and why does it matter?

Homeostasis has become the central unifying concept of physiology and is defined as a self-regulating process by which an organism can maintain internal stability while adjusting to changing external conditions. Homeostasis is not static and unvarying; it is a dynamic process that can change internal conditions as required to survive external challenges. (Billman, G. E. (2020). Homeostasis: the underappreciated and far too often ignored central organizing principle of physiology. _Frontiers in Physiology, 200.)_

_Homeostasis denotes the maintenance, or regulation, of vital internal variables in a state of relative constancy. Automatic cellular mechanisms, neural and endocrine controls, and behavior all contribute importantly to homeostasis. Organisms that function in wider ranges of external environments tend to regulate more internal variables and to have more complex systems regulating important variables – for example, the adaptable mechanisms with which we mammals regulate body temperature allow us to function in a much wider range of external temperatures than reptiles. Most physiological homeostatic mechanisms rely on negative feedback; that is, signals related to the regulated variable are sensed and cause the system to react in a way that reduces the signals. (_Asarian et al. Homeostasis. Encyclopedia of Human Behavior (Second Edition), 2012).

So homeostasis matters because it allows us to continue functioning in a wide variety of environments and to cope with changing demands.