Posted by Click Aquí para leer este post en español
Hey Life Warriors!
Not long ago we published a post about arguably the greatest threat to our health in the developed World: the metabolic syndrome, and in that post we explained to you how stress is one of the main rooting factors of this problem. Since stress seems to be one of the greatest issues we will probably have to face (if you are not facing it already), we are going to share a short post series that will help us:
- Understanding stress and its effects on our health
- Learning how to identify the different sources of stress
- Developing strategies to fight it
There are some concepts that probably are not totally clear today and we need to understand. Once again, with the help of my good friend Nuria, great MD and oncologist, and some sources that we consider reliable (check the bottom of the article to see them) we will try to shed some light.
From a psychological perspective, we can define stress as a situation which the individual perceives as difficult or impossible to manage with the available resources. This situation will cause a series of physiological and behavioral reactions.
One important aspect of this definition is that stress is based on our own perception that a certain event or situation will pose a threat or a difficulty for us, which does not have to be necessarily true. Very frequently we anticipate these difficulties which may end up not being real, which we will deal with when we talk about the anti – stress strategies in an upcoming post.
How does our body react to a stressful situation?
When we are facing a difficult situation, either physical (a risk to our physical integrity, like an external attack or extreme weather conditions) or intellectual (an upcoming deadline, a presentation or any other work related challenge), our body reacts, turning on the “alert mode”. The information is sent to the amygdala, which interprets it and sends an alarm signal to the hypothalamus, our body’s communications center.
The hypothalamus is a bit like a command center. This area of the brain communicates with the rest of the body through the autonomic nervous system, which controls such involuntary body functions as breathing, blood pressure, heartbeat, and the dilation or constriction of key blood vessels and small airways in the lungs called bronchioles. The autonomic nervous system has two components, the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system functions like a gas pedal in a car. It triggers the fight-or-flight response, providing the body with a burst of energy so that it can respond to perceived dangers. The parasympathetic nervous system acts like a brake. It promotes the “rest and digest” response that calms the body down after the danger has passed.
After the amygdala sends a distress signal, the hypothalamus activates the sympathetic nervous system by sending signals through the autonomic nerves to the adrenal glands. These glands respond by pumping the hormone epinephrine (also known as adrenaline) into the bloodstream. As epinephrine circulates through the body, it brings on a number of physiological changes. The heart beats faster than normal, pushing blood to the muscles, heart, and other vital organs. Pulse rate and blood pressure go up. The person undergoing these changes also starts to breathe more rapidly. Small airways in the lungs open wide. This way, the lungs can take in as much oxygen as possible with each breath. Extra oxygen is sent to the brain, increasing alertness. Sight, hearing, and other senses become sharper. Meanwhile, epinephrine triggers the release of blood sugar (glucose) and fats from temporary storage sites in the body. These nutrients flood into the bloodstream, supplying energy to all parts of the body.
All of these changes happen so quickly that people aren’t aware of them. In fact, the wiring is so efficient that the amygdala and hypothalamus start this cascade even before the brain’s visual centers have had a chance to fully process what is happening. That’s why people are able to jump out of the path of an oncoming car even before they think about what they are doing.
As the initial surge of epinephrine subsides, the hypothalamus activates the second component of the stress response system, known as the HPA axis. This network consists of the hypothalamus, the pituitary gland, and the adrenal glands.
The HPA axis relies on a series of hormonal signals to keep the sympathetic nervous system — the “gas pedal” — pressed down. If the brain continues to perceive something as dangerous, the hypothalamus releases corticotropin-releasing hormone (CRH), which travels to the pituitary gland, triggering the release of adrenocorticotropic hormone (ACTH). This hormone travels to the adrenal glands, prompting them to release cortisol. The body thus stays revved up and on high alert. When the threat passes, cortisol levels fall. The parasympathetic nervous system — the “brake” — then dampens the stress response.
Why stress is negative?
Stress is necessary for our own safety and survival, and it really helps us when the situation requires immediate action, so we should not think of it as something negative per se.
The problem comes when this physiological reaction is sustained over long periods of time. In the same way that we are not able to maintain a 100 metres sprint intensity during a 10 km race, stress is designed to provide a rapid response and should disappear as rapidly as it appears.
When this does not happen and the stress situation is sustained, allostatic load appears. This means that our body tries to recover after a stressful event, but it fails to do it because the stressor remains active, so we make the arrangements to be able to live with this stress overload. In this way, a new balance is generated but in this new state, our capacity to deal with new stressors is much lower (ref). Allostatic load produces very negative effects in our health: repeated epinephrine surges damage our circulatory system by the increased blood pressure, which increases our chances of suffering a stroke. On the other hand, high cortisol levels impair our cognitive capacities. More specifically, our capacity to consolidate information, execution and decision making are affected. It also makes us hungrier but it decreases our fat burning capabilities, which means that another undesired effect of stress is fat gain.
We hope we have not got too technical and that this post helps you understand a bit better all the mechanisms and reactions triggered by stress. In our opinion, the first step we should take to tackle an issue is getting a complete undestanding of how that issue is originated and what all its effects are, with the intention of being more efficient to fight it.
That will be it for today; in our next post we will be talking about the main sources of stress and how to identify them. Don’t miss it!!
References:
- Carga alostática, estrés y soluciones – National Geographic
- Understanding the stress response – Harvard Health Publishing. Harvard Medical School
- Efectos del estrés en el cerebro y la depresión con Carmen Pedraza – Fitness Revolucionario
Main Post Image: Foto de Ordenador creado por master1305 – www.freepik.es