Stress: What it is, Types and Causes of Stress

The term stress comes from physics: the pressure exerted by one body on another, with the one that receives the most pressure being the one that can be torn apart. 

What is stress?

It is similar in humans and animals and is a physiological reaction of the organism, not a disease. It is a defence mechanism to cope with a situation that is perceived as threatening. It is a natural and necessary response for survival. If permanent stress occurs, then it is a disease

Types of stress

Eustress or Positive Stress

With positive consequences for the stressed subject (survival). Among its characteristics we find that it motivates, focuses energy, improves performance, and increases confidence. On the other hand, it is a short-term stress.

Distress or Negative Stress

With negative consequences (illness or pathology), whose characteristics: produces anxiety and/or worry, decreases performance, unpleasant or uncomfortable feeling. It can be short or long term. It can also produce mental and physical problems.

Sometimes, for a short period of time, stress can be helpful in accomplishing a task.

Stress components

Stress is the body’s response to a change. In this sense, we can speak of an alteration of homeostasis, triggering a series of physiological reactions within our organism, enabling it to cope with guarantees and come out of the stressful situation with flying colours, in the event of an imminent risk.

Stress is, after all, a strain placed on an organism, forcing it to change and adapt according to conditions.

Stress and nervous system

The nervous system can be considered as a system with somatic (voluntary) or autonomic (involuntary) functions. The former is responsible for the activation of skeletal muscles, while the latter controls involuntary actions, such as heart rate. Therefore, it is precisely the sympathetic system that will rule in a stressful situation as opposed to the autonomic system.

This procedure is what allows us to survive when we come across any dangerous situation and makes us react almost immediately (dodge, jump, sprint…). 

Main causes of stress

There are variables that make this change, the emotions, which are ways of adapting to the stressor: anger, fear, guilt, sadness, relief…

How do we react to stress?

When faced with a threat that may involve unusual mental or physical exertion, and preparation for possible injury or emotional distress, the body has instinctive mechanisms to prepare and ensure that we are in the best possible state to combat the problem and survive.

These changes involve the brain, nervous system, blood circulation and muscles, as well as mental and emotional attitudes that work differently from normal. 

Stress response

This process prepares the body to fight or flee from a perceived threat (known as the fight or flight response).

What changes occur in the body when we are under stress?

When the source of the threat is detected by our senses, the signal is sent to the amygdala, an area of the brain responsible for emotional processing, where images and sounds are interpreted. If danger is perceived, the hypothalamus is instantly alerted (a “distress signal” is sent). The hypothalamus communicates with the rest of the body via the autonomic nervous system. It also activates the sympathetic system by sending signals that will affect the adrenal glands. This organ is responsible for releasing certain hormones into the bloodstream, such as epinephrine.

All these changes occur at such a speed that the person is not able to fully visually perceive and process the threat or risk in front of them.

Once they circulate in the blood, a series of physiological changes will occur:

Cortisol and stress

As epinephrine release decreases, the hypothalamus triggers another component of the stress response, known as the Hypothalamic-Pituitary-Adrenal Axis (HHA Axis). This interconnects the hypothalamus, the pituitary gland and the adrenal glands. The sympathetic system remains activated. If the brain continues to detect threat, the hypothalamus releases adrenocorticotropic hormone-releasing hormone (CRH) which travels to the pituitary gland, releasing adrenocorticotropic hormone (ACTH), which releases cortisol.

The body thus remains accelerated and alert. When the threat passes, cortisol levels drop, and it is again (if all goes well) the parasympathetic nervous system, which dampens the stress response, and is once again “in control”.

How does stress affect the brain?

The amygdala is not only the first to alert us to the potential risk of threat, but it is also responsible for storing the experience in our memory. Any stressful situation that involves making a decision to fight or flee will be recorded in our brain, so that although it may seem illogical, by imagining the possible situation or remembering it, the whole process described above can be restarted.

The stress response can be initiated by a perceived threat or a real threat. The threat does not even have to be real for this to start. An imagined threat can initiate a physical response.

Effects of chronic stress

When stress goes from being a one-off event to becoming a constant almost every day, it produces a series of alterations at all levels within the organism, so that our organism is unable to return to a state of homeostasis, substantially reducing our well-being and even affecting our professional, academic or social life:

Tips for managing stress

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