Homeostatic Control
Living organisms have a limited range of environmental and physiological conditions in which they can operate. When these conditions change rapidly, organisms must adapt quickly to preserve their life. To maintain a delicate equilibrium for survival, living organisms have processes that allow them to counter potentially dangerous external or internal stimuli. This concept of always trying to return to a state of balance is called homeostasis. Homeostatic systems address a variety of stimuli and dangers within an organism.
The human body has numerous homeostatic regulation pathways, including:
- body temperature
- blood pH
- breathing and gas exchange,
- body water and electrolyte content
- blood pressure
- calcium levels
- feeding and digestion
- hormonal regulation
- blood sugar levels.
Homeostatic pathways typically have a basic workflow that includes sensors, a control center, effectors, and a feedback loop.
When the intensity of a stimulus exceeds a tolerance threshold value, the body activates homeostatic pathways to counteract it. For example, when the body gets too warm, it starts sweating and dilates blood vessels to dissipate body heat. The body reaches a stable state, different from the normal resting state, but stable enough not to cause irreversible damage. When the stimulus decreases or disappears, the homeostatic systems return the body to the initial balance. However, if the intensity or duration of the stimulus is too great, the homeostatic control may be unable to cope, leading the body to enter a state of shock or rapid self-degradation.
Homeostatic regulation pathways are not always independent from each other, and some may impact similar physiological variables. For instance, the homeostatic response to cold temperatures triggers muscles to shiver, consuming blood sugar by muscle tissues. Therefore, another homeostatic process has to act to maintain blood sugar levels.