Stress

Stress is quite normal

The word stress has a negative connotation when in fact stress is quite normal. Acute stress is good; it gets you moving. But too much acute or prolonged stress has a negative effect on the body.

Our body is always striving for a balance both physically and mentally. We distinguish between acute and chronic stress. Acute stress is short-term stress. If stress becomes long term then it is unhealthy and we call it chronic stress.

Our body has 2 nervous systems: the central nervous system and the autonomic nervous system. The autonomic nervous system can be divided into the parasympathetic and the sympathetic. The parasympathetic is responsible for rest and recovery, while when stressed, the sympathetic is active.

Acute, short-term stress

In acute or short-term stress, the stress hormones adrenaline and noradrenaline are secreted by the adrenal glands. The brain stem, the oldest part of our brain, responds by increased heart rate, accelerated breathing, muscles tighten and sensory stimuli are perceived more strongly. Then the limbic system, the emotional brain, will associate an emotion with this.

Finally, the hypothalamus in the brain releases the hormone CRH (corticotropin-releasing hormone). This stimulates the pituitary gland to produce ACTH (adrenocorticotropic hormone), which instructs the adrenal glands to produce cortisol.

During a stress response, the HPA axis is activated, in Dutch HHB axis; hypothalamic-pituitary-adrenal axis. This HPA axis regulates the control of the adrenal glands.

Chronic stress

Continuous activation of the HPA axis leads to constantly excessive levels of cortisol in the blood (hypercortisolemia). In such a situation there is chronic stress. The innate immune system* is stimulated and energy is released to the organs necessary for survival.

Because the body is always looking for a certain balance (homeostasis), it will conserve energy on processes that are not necessary to handle this (chronic) stress. Consequently, thyroid function may slow down. This affects digestion, among other things, resulting in decreased production of digestive enzymes. The effect is reduced nutrient absorption. In addition, the pressure on the pancreas and liver is increased because of the increased demand for glucose.

Chronic stress is detrimental to a variety of processes in the body, including regeneration and the production of various hormones.

If chronic stress persists for a long time then it progresses according to several stages to eventual exhaustion, or burnout. In this phase, cortisol is reduced (hypocortisolemia). Also, DHEA (a hormone also produced in the adrenal glands and a counterpart of cortisol) and thyroid hormones are lowered.

Only when the triggering stressor is resolved then the sympathetic is turned off.

The innate immune system is present at birth. There is also an acquired immune system. The innate system is a fairly primary system: it responds quickly but is not very selective. We also call it nonspecific defense. It responds to anything foreign to the body but it has no memory cells.

The acquired immune system, also called adaptive immune system, works much slower and after signaling, proceeds more precisely. It works very selectively and only becomes active after some time. It also keeps an archive by means of memory cells so that the next infection can be dealt with very quickly. Thus immunity is built up.

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Written by: Liesbeth Thoen
Reviewed and edited by: Peter Smeets

Updated on: March 17, 2022