Biomedical Engineering Reference
In-Depth Information
accompanied by higher physical readiness. The stress axis is taking
care of the body that is being made ready for action.
Physical readiness is a result of an autonomous brain process that
takes place without much interference from external circumstances or
consciousness. The stress axis is an activity of the basic brain, that is,
the hypothalamus and the brain stem (the top part of the spine in the
skull). The hypothalamus sends signals to the adrenal gland that is sit-
uated on top of the kidney. This gland produces two hormones, corti-
sol and adrenalin. Both hormones have a comparable effect. Cortisol
is mostly associated with stress and works fast and in short spurts. It
shakes up the body, makes it awake, and increases the sugar level in
the blood. Adrenaline covers a longer-lasting raise of general activity
in the body by raising blood pressure and heart frequency, which
results in a strong blood circulation. Due to this combination, muscles
receive extra blood, filled with fuel. They are ready for action. The
basic muscle tone increases, which can create a
“
”
sensation.
Readiness requires energy. As soon as it is no longer needed, the body
changes to a normal mode. The stress axis can be activated by activity
in the amygdala and the hippocampus (risk sensitivity), and can be
reduced by the prefrontal cortex (safety intuition) (Root et al., 2009).
speedy
6.4 SUMMARY
Consciousness makes life special but it is hard to define. Unlike other
functions, consciousness is not generated by a single area, but only if a
