Homeostasis, which literally means ‘same standing’ from the Greek words for "same" and "steady," refers to any process that living things use to actively maintain fairly stable conditions necessary for survival (Clancy et al., 2011). It is a term introduced by Cannon in 1930 to describe the goal of all the body’s physiological processes. These processes dynamically maintain a relatively constant state called steady-state in the internal environment (CREDO, 2006). The internal environment is the fluid that surrounds cells, which refers to the direct cell survival and material exchange with the environment. The processes maintain the internal environment steady levels of temperature and other vital conditions such as the water, salt, sugar, protein, fat, calcium and oxygen contents of the blood by many systems operating together (Rodolfo, 2013). When the body cannot maintain homeostasis, cells cannot carry out their normal functions, which include considerable adverse effects, such as cellular rupture. Those who are not in Homeostasis are often accompanied by sickness (Silverthorn, 2009 and Kelly, 2004).
Because of the constantly changing environment of the body, adjustments must be made continuously to maintain the internal environment within the set point limit by a variety of homeostatic mechanisms. Therefore, Homeostasis can be considered as synthetic equilibrium, which means constant monitoring to achieve internal balance (Marieb, 2012).
To maintain homeostasis in the body, it requires all the body systems work together, while the nervous and endocrine systems play the most important role. The nervous system reacts quickly to external and internal stimuli, whereas the endocrine system is slower to act but its effects are longer lasting. In addition to the internal control mechanisms, our body's ability to maintaining cellular health is also influenced by external influences based primarily on lifestyle choices and environmental exposures such as medication invention (Barber et al., 2009).
When a homeostatic disturbance occurs, inbuilt and self-adjusting or regulating mechanisms come into effect (Clancy et al., 2011). These mechanisms operate as a feedback system, mainly on the negative feedback which is an automatic response that involves a corrective mechanism to reverse the original change and brings the variable or factor within the internal environment back to normal limit. It is continually ongoing to restore and maintain homeostasis (Marieb, 2012, CREDO, 2006 and Kelly, 2004). The feedback system involves three parts: the receptor, the controller and the effector. The receptor is a sensor to detect and collect the environment shifting information. Then the information from the receptor is received and processed by the controller. At last, the effector responds to the controller’ commands by either enhancing or opposing the stimulus. For instance, when the blood's pH level shifts out of the set point, nerve receptor cells...