Homeostasis : "Same" & "Steady"

Homeostasis : 

The ability to maintain steady intracellular pH and constant osmotic differential across the cell membrane termed as "Homeostatis".

Homeostasis derived 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.

Homeostasis is the state of steady internal, physical, &  chemical conditions maintained by living systems.

The term was coined in 1930 by the physician Walter Cannon.

                Walter Bradford Cannon

About :

Walter Bradford Cannon was an American physiologist, professor and chairman of the Department of Physiology at Harvard Medical School. He coined the term "fight or flight response", and he developed the theory of "homeostasis"

                Walter Bradford Cannon

pH Homeostasis :

The external pH - internal pH is usually maintained within 1-2 units of neutrality which is necessary to maintain viability.

Examples :

1.Bacteria grow optimally between pH 1-4 (i.e.acidophiles) have an internal pH of about 6.5-7.That is to say they maintain ΔpH of greater than 2.5 units inside alkaline.

2.Bacteria grow optimally between pH 6-8 (i.e.neutrophiles) have an internal pH of about 7.5-8.They maintain ΔpH of 1.5 units, inside alkaline.

3.Bacteria grow at pH 9-12 or above (i.e.alkaliphiles) have an internal pH of 8.4-9. therefore, they maintain ΔpH negatively of about 1.5-2 units, inside acid.

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