Life’s Balancing Act


Here is a concise definition of homeostasis:  Homeostasis is a dynamic state of internal equilibrium that all living things must maintain to stay alive and healthy.


In order to stay healthy our bodies need to maintain certain ranges of such things as oxygen, glucose, blood pressure, temperature, electrolytes, water, etc.  These are all part of the environment in which our cells live, and we need to keep a healthy balanced environment for those living cells.  That’s homeostasis.


Example homeostatic ranges:

  • Blood oxygen:  95-100% hemoglobin saturation is the homeostatic range.
    • Our cells need a certain amount of available oxygen at all times.  Oxygen saturations lower then 90% sturation can cause dizzyness, rapid breathing (as the body tries to maintain oxygen homeostasis), and if it gets to low we can pass out and ultimately die.  Asthma, COPD, and other respiratory disorders cause problems with oxygen homeostasis.  It’s less likely, but possible to become hyperoxic (too much oxygen in the body).  If this happens the oxydative molecules produced can damage many molecules in the cells including DNA and proteins which can cause multiple problems.
  • Body temperature:  Around 97 to 99 F (36.4 to 37.6 C) is the normal homeostatic range for oral temperature.
    • If we go above or below that level the enzymes in our cells decrease their function and this can cause widespread organ failure if it goes to far.  Oral temperatures above 104 F (40 C) is worse because not only do the enzymes stop functioning but that can be damaged.  Reviving someone with deadly hypothermia is more successful that reviving someone with deadly hyperthermia.
  • Blood sugar:  90-100 mg/dL is the homeostatic range
    • If blood sugar gets to high for long periods long term problems with small blood vessels develop (blindness, kidney failure, neuropathies, etc) and if it gets to low we can get shaky and lethargic and may pass out…  further drops can be deadly.  Diabetes mellitus and hypoglycemia are disorders involving glucose homeostasis.

After reading this you should understand that homeostasis is very important.  You should also get that there are several factors to the bodies internal environment that have to be maintained within a certain homeostatic range in order to stay healthy and alive.  It’s a balancing act that our bodies maintain 24 hours a day for our entire lives.  Our bodies have multiple ways to maintain homeostasis depending on the environmental variable, but pretty much all of them have the same basic mechanism called negative feedback…  Let’s cover that next.


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