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Homoeostasis – is defined as the tendency to move towards a state of equilibrium. It is performed by the hypothalamus in the Limbic brain, which forms a bridge between the nervous system (which sends the instructions) and the endocrine system (which controls the operating parameters of the physical body). The homoeostasis circuity operates within the unconscious limbic brain to keep the body running as it should – temperature, water, metabolism, growth, sexual reproduction, etc. We don’t think about it very much because in most people it works very well and helps ensure that our physical body is ready and willing when we need it to do something.
A hindrance on the spiritual journey
Our body decides at an early age what its preferred state of equilibrium is. From then on, it is something that we have to work against if we want to make spiritual progress. Homeostasis may be a state of rest for the body and mind, but it is counter-productive to progress. If you want to run a marathon then you need to exercise pushing the limits of your body. This works against the tendency towards homeostasis. The same applies if you are striving to improve how you use the brain. It is easier to work against the homeostasis circuitry than it is to fight the reward system.
The body maintains its working parameters through simple feedback circuits. Open and closed loop feedback circuits are widely studied in electronics, and the human body is little different (see diagram below) .
A reference input is required which is compared with the output being measured. Any difference is fed back and used to correct the error (negative feedback). The amygdala and hypothalamus are involved in maintaining the body’s homeostasis through negative feedback loops. Examples include:
- blood pressure
- glucose levels
- blood pH
- oxygen and carbon dioxide levels
- body temperature
Positive feedback loops result in oscillation. They are also useful in certain circumstances, and usually have an off switch to end the behaviour. Examples of positive feedback loops in the body include:
- child birth (contractions begin and increase until the baby is expelled from the Mother’s body)
- clotting of blood (the coagulation of platelets stops when the blood leak has been blocked)
- lactation (the process ceases when the baby is a certain age)
- nerve action potential
- cancer – this is an unwanted positive feedback condition. It may stop only when the body is dead.