stress fysiologi

Stress fysiology

What is stress and how does it affect our body?

Stress, that word so common in our society. When I ask my patients what they do for a living, I always ask if their work causes them stress and if it affects their body. And in most cases, it is a resounding yes.

We are all familiar with long working hours, fast food without taking off our screens, artificial light bombarding us at all hours, insufficient sleep that leads to the consumption of stimulants to get through the day, and social relationship problems both at work and at home. the group of friends and family.

Unfortunately, the pace of today’s society is far from what we would like. How many times have we wished for the weekend to come to turn off the alarm clock or escape to the mountains to relax and breathe fresh air? In fact, it is physiologically normal for our brains and bodies to seek peace, nature, real food, and rest. They are natural stimuli that we have received from our origins and that little by little have been diminishing.

Acute: Epinephrine and Norepinephrine

Physiologically, stress is an acute survival strategy that, evolutionarily, allowed us to save our lives.

When exposed to a situation of acute stress, the body activates the sympathetic nervous system, with the consequent release of hormones such as adrenaline and noradrenaline, which generate the necessary inflammation to escape from the acute stress situation, stay awake or overcome a challenge or difficulty. In addition, this situation allows us to prepare our body for the “fight” or “flight” response since most of the energy will be directed to the muscular, respiratory and circulatory systems to increase muscle tension, heart rate and blood pressure.

In short, acute stress generates a rapid response of short duration (30-50 minutes) in which adrenaline and noradrenaline play a key role.

For example, if I miss the bus and I’m late for a very important meeting, this acute physiological response is activated so that I can run and catch it.

The famous cortisol

Once the acute stress situation is over, our beloved and well-known cortisol enters the scene.

Physiologically, the inflammation generated by the activation of the sympathetic nervous system is unsustainable in the long term. For this reason, after 30 to 50 minutes, the generation of the hormone CRH is activated. It acts on the pituitary gland by releasing ACTH, which in turn controls the production of cortisol in the adrenal glands.

Cortisol has the function of modulating that inflammation and curbing that acute stress response. Therefore, adequate levels of cortisol fulfill beneficial functions:

  • Control of the immune system and anti-inflammatory effect.
  • Circadian regulation together with melatonin → We need a rise in cortisol early in the day. This allows us to activate, wake up and face the day. This cortisol spike decreases at night and allows melatonin to increase, making it easier to fall asleep.
  • Increased cognitive function → In optimal amounts, cortisol activates neurons and NMDA receptors that serve to increase cognitive function and memory.

The problem occurs when these stressful situations are prolonged over time and cortisol remains very high.

Using the same analogy as above, high workloads, complicated relationships or family problems can be situations of sustained stress that affect our body… During prolonged stress, the body activates the same mechanisms, but when these are not resolved, high levels of cortisol are keep in time. Physiologically, for the body it is as if a lion were chasing you all your life… As you will see below, this has certain long-term consequences.

Consequences of a stress axis maintained over time

Increased blood pressure → Other types of hormones, apart from cortisol, are also produced under the stimulation of ACTH. One of them is aldosterone, which will lead to the production of vasopressin, increasing blood pressure.

Difficulty losing weight → Cortisol triggers the release of glucagon in the liver, which constantly releases glucose into the blood. If we always have glucose available to our body, it will cost much more to burn fat.

Loss of muscle mass → In a situation of stress, our body can be affected: the body will save energy, which will cost allocate that energy to muscle growth and maintenance processes.

Joint pain → Cortisol can cause an imbalance in the bone synthesis-destruction balance, favoring bone resorption and decreasing calcium absorption, resulting in low bone mineral density.

Metabolic problems and insulin resistance → Insulin is the hormone that allows glucose to enter all body tissues to generate energy. However, due to the hierarchy of vital priorities, when we have an alarm situation, the body will allocate energy to resolve the inflammation and prevent that energy from being lost in other tissues by generating insulin resistance. As a result, the cells will be less sensitive to insulin and we will have more insulin and glucose in the blood, causing metabolic syndrome, diabetes, hypertension…

Digestive problems → To promote good digestive functionality, it is necessary to activate the parasympathetic nervous system, for relaxation. If, on the other hand, we have stress, the sympathetic nervous system is active, body functions of fight or flight are prioritized, so multiple digestive functions will be impaired, leading to the appearance of different functional disorders.

Second phase of stress:

Adrenal fatigue and cortisol depletion
We must also consider that at a certain point, the adrenal gland can become fatigued and stop synthesizing cortisol, and this also has negative consequences:

Recurrent infections and allergies → Due to the anti-inflammatory function of cortisol, if we have low levels in the long run we will tend to immunosuppression and therefore we will be more exposed to pathogens and allergies.

Problems in the menstrual cycle: Amenorrhea and hypothyroidism → In a situation of chronic stress, if the brain perceives that there is no energy, it will inhibit the entire reproductive and thyroid axis, since they are very energy-demanding processes. The result will be amenorrhea and hypothyroidism.

Sleep disturbance due to deregulation in melatonin → It is necessary to generate a rise in cortisol in the morning and a fall in the afternoon so that melatonin can increase. If we have very high cortisol throughout the day, it will be difficult for melatonin to rise. In the same way, if we have low cortisol all day due to adrenal fatigue, melatonin will not rise either.

Tiredness, apathy and difficulty starting the day → As we have mentioned, cortisol is necessary to start the day with energy and face tasks with motivation. If we are fatigued and do not generate enough cortisol, it will be difficult for us to start the day and we will be more tired.

And the eternal question, how to solve stress?

Throughout the post, we have learned that long-term stress in our body affects multiple functions of our body and can seriously affect our health. Now, how can we improve or reverse this situation?

Fortunately, we have many tools to alleviate stress, as well as improve our standard of living. For example, meditation, physical activity or relaxation techniques are highly recommended activities.

However, these techniques try to modulate the symptoms without treating the root problem or assessing the origin of the stress. In fact, decision-making, individualization, the biopsychosocial context of the person will be pieces that must fit together to eradicate the root causes of stress. And here lies the true key and essence of clinical NIP.

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