Stress is an emotion that appears when we find ourselves in a situation in which we perceive that our life or well-being is threatened. This emotion involves the activation of several organic mechanisms that are oriented towards having sufficient energy to be able to face the perceived threat.
As an emotion, it has a neurological substrate, it affects our nervous system. Depending on whether it is a one-time or chronic stress, it will affect our body in one way or another.
Next we will discover What changes occur in our nervous system when we are stressed
What effects does stress have on the nervous system?
Stress is an emotion that arises when some change or unforeseen event is perceived in the environment. The function of such emotion is to prepare our body to give a satisfactory response to such changes, arising when the individual feels that the situation exceeds the resources he believes he has available.
Definitely, Stress helps us gather all the necessary forces to emerge victorious from the emotionally tense situation.
This mechanism involves a physiological response, activating a series of processes at an organic level to be able to face whatever is necessary. When we are stressed our cardiovascular, metabolic, immune and neuroendocrine systems undergo several changes, all of them to obtain enough energy in the form of glucose so that the muscles can perform fight or flight behavior and overcome the situation.
Next we are going to see in detail what changes occur in different components of the nervous system when a stress response occurs.
The autonomic nervous system It takes on a very important role in situations that cause us stress When we perceive a threat, half of this system is activated and the other is inhibited. These systems are the sympathetic and the parasympathetic.
sympathetic nervous system
The part of the autonomic nervous system that is activated is the sympathetic Although its origin is in the brain, its projections radiate from the spinal cord, contacting all the organs, blood vessels and sweat glands of the body. This component of the nervous system is activated when the brain considers that it is in an emergency situation.
When this system is activated, the hypothalamus gives the order to increase the activity of the adrenal glands This is a rapid activation of the so-called sympathetic-adrenal-medullary (SAM) axis, releasing adrenaline and norepinephrine, two fundamental neurotransmitters in the stress response.
parasympathetic nervous system
The other half of the nervous system, the one that is inhibited, is the parasympathetic, which behaves this way so as not to hinder the work of the sympathetic system and facilitate the activation of the necessary structures. to be able to give an adequate response to what has activated the response stressful on the body.
Effects of stress on the brain
Stress increases the activity of various brain structures to prepare it for future demands. This is the hypothalamic-pituitary-adrenal or HPA axis which allows you to resolve short-term stress situations in the face of threats in the following way.
First, The hypothalamus releases a special hormone, corticotropin (CRH) This hormone stimulates the pituitary gland to release another substance: adrenocorticotropin (ACTH). This action causes the adrenal glands to secrete three more hormones: adrenaline, norepinephrine and cortisol.
Adrenaline and norepinephrine are catecholamines and these increase blood pressure and heart rate. It is also what causes when we are nervous and stressed the blood flow to be diverted from the gastrointestinal system to the muscles, paralyzing digestion and focusing all the forces and energies to be able to react physically if necessary.
Cortisol causes glucose to be released, necessary action so that the body has enough energy to be prepared for the demands of the situation. Furthermore, in case of wounds or injuries, cortisol serves to prevent inflammation. The muscles receive blood and sugar to increase strength, the brain increases its concentration so that body and mind can work together to survive.
Effects of chronic stress on the nervous system
Stress triggers glucocorticoid levels in the bloodstream, so Chronic stress can have harmful effects on the body, especially with neurons and their branches being sensitive There are structural and functional changes caused by chronic stress in the brain, which as a consequence induce mood disorders and behavioral and physiological changes.
Chronic stress inhibits glucose uptake by neurons, which alters its development and growth. Additionally, too much stress triggers a biochemical cascade in the form of more neuronal synapses, especially in the hippocampus and prefrontal cortex.
This causes overactivation in these areas, damaging neurons and causing the degradation of their cytoskeleton. Also malformation of neuronal proteins and generation of oxygen radicals occur, which cause neuronal death
The hippocampus, amygdala and prefrontal cortex are structures that are very susceptible to changes, and stress is one of those factors that contributes to their remodeling. The degree of reversibility of such alterations will depend on the duration and potency of the stressors and the amount of neurochemical substances that the stressful episode has released. This brings with it not only cognitive effects, but also involves changes in emotionality, behavior and neuroendocrine functions of the individual.
As we said in the previous section, one of the brain structures most sensitive to changes is the hippocampus. This structure has a high concentration of glucocorticoid receptors and, as a key structure in learning, it is very susceptible to change due to its brain plasticity, necessary to house new knowledge. The hippocampus is involved in creating new memories by strengthening neuronal connections. It does not store memories, but it promotes networks that allow previous experiences to be associated.
In the short term, stress causes more oxygen and glucose to reach the brain, which is positive because it increases the activity of this structure and enhances the memory of the stressful situation. This has the advantage that, if what caused us stress happens again, we quickly remember how we handled the situation and thus emerge victorious more quickly.
But if stress becomes chronic, Glucose and oxygen levels decrease and hippocampal neurons begin to atrophy damaging the connections between them and causing memory problems. This also induces neuronal death.
Effects on the prefrontal cortex
In people exposed to constant stress, The prefrontal cortex presents a general reduction in size a consequence of structural and functional changes in their neurons associated with prolonged exposure to glucocorticoids.
Silk a general decline in executive functions, with worse decision making, low emotional self-regulation and loss of attention, affecting the individual’s coping abilities. Working memory is also affected.
Effects on the brain amygdala
Stress increases neuronal activity in the amygdala and connections with other regions of the brain. This makes people under chronic stress more aggressive with fear and anxiety. This makes them more susceptible to behavioral and emotional alterations, with psychopathology such as depression.
