Animal organs and organ systems constantly adjust to internal and external changes through a process called homeostasis ("steady state"). Examples of these changes include regulation of the level of glucose or calcium in the blood or internal responses to external temperatures. Homeostasis requires  maintaining an internal dynamic equilibrium:

Maintaining homeostasis requires that the body continuously maintain its internal conditions. Each physiological condition has a particular set point, from body temperature to blood pressure to levels of certain nutrients. A set point is the physiological value around which the normal range fluctuates. A normal range is a restricted set of values that is optimally healthful and stable. For example, the set point for normal human body temperature is approximately 37°C (98.6°F).

Human anatomy is the scientific study of the body's structures. Some of these structures are very small and can only be observed and analyzed with the assistance of a microscope. Other larger structures can readily be seen, manipulated, measured, and weighed. The word "anatomy" comes from a Greek root that means "to cut apart." Human anatomy was first studied by observing the body's exterior and the wounds of soldiers and other injuries. Later, physicians were allowed to...

Homeostasis is the maintenance of a stable internal environment within the body, which is crucial for the proper functioning of cells, tissues, organs, and organ systems. The body has various control mechanisms that work together to regulate various physiological parameters such as temperature, blood pressure, pH balance, and fluid balance, to name a few. These control mechanisms are based on feedback loops that can be either positive or negative.
However, sometimes these feedback loops fail,...

Acid-base homeostasis is essential for maintaining normal physiological activities in humans. The pH of various body fluids is strictly regulated because it is critical for the optimal activity of enzymes involved in metabolic reactions. Enzymes are basically proteins, so, any significant change in pH can affect their structure and activity. In humans, pH is regulated using three primary mechanisms— chemical buffer systems, respiratory regulation, and renal regulation.
Respiratory...

An important concept in studying metabolism and energy is that of chemical equilibrium. Most chemical reactions are reversible. They can proceed in both directions, releasing energy into their environment in one direction, and absorbing it from the environment in the other direction. The same is true for the chemical reactions involved in cell metabolism, such as the breaking down and building up of proteins into and from individual amino acids, respectively. Reactants within a closed system...