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The biochemistry of stress: how the body responds to anxiety at the molecular level
What is the biochemistry of stress?
The biochemistry of stress is a branch of neurobiology and physiology that studies how the body's chemicals change in response to psycho-emotional or physical stress. Stress is not only a subjective feeling of anxiety, but also a clearly regulated response of the neuroendocrine system, which affects all organs and systems.
How stress works: a staged response
Activation of the hypothalamic-pituitary-adrenal axis (HPA axis)
When a person feels threatened (physical or psychological), the hypothalamus activates the production of corticotropin-releasing hormone (CRH), which stimulates the pituitary gland. The pituitary gland, in turn, produces adrenocorticotropic hormone (ACTH), which acts on the adrenal glands.Release of cortisol and adrenaline
The adrenal glands begin to massively produce cortisol (glucocorticoid) and adrenaline.
Cortisol: increases glucose levels, reduces immune response, affects mood and memory.
Adrenaline: speeds up the heartbeat, constricts blood vessels, prepares the body for the "fight or flight" response.Neurotransmitter changes
The brain changes level dopamine, serotonin, norepinephrine, which affects mood, attention, and motivation. In long-term stress, an imbalance of these substances is associated with depression and anxiety disorders.
Table: Main substances involved in the biochemistry of stress
| Substance | Source | Function under stress |
|---|---|---|
| CRH | Hypothalamus | Activation of the stress response |
| ACTH | Pituitary | Adrenal stimulation |
| Cortisol | Adrenal glands | Glucose, immune response, energy |
| Adrenalin | Adrenal glands | Cardiovascular activation |
| Noradrenaline | Brain, adrenal glands | Alertness, tone, vascular reactions |
| Dopamine | Brain (mesolimbic system) | Emotions, motivation |
| Serotonin | Brain, intestines | Mood, appetite, sleep |
The consequences of prolonged stress at the biochemical level
Increased cortisol level → decreased immunity, insulin resistance
Decreased serotonin → depressive symptoms, sleep disturbances
Excess adrenaline → tachycardia, blood pressure, arrhythmia
Inflammatory changes: prolonged stress activates pro-inflammatory cytokines (IL-6, TNF-α)
Loss of neuroplasticity: signal transmission is disrupted in the hippocampus, reducing the ability to learn and adapt
What the research says
In accordance with Mayo Clinic, chronic stress is directly linked to cardiovascular disease, diabetes, and obesity.
[NIMH (National Institute of Mental Health)] reports that long-term stress alters brain activity, particularly the prefrontal cortex, which affects decision-making.
WHO emphasizes that psychosocial factors (work stress, trauma, social isolation) are the main triggers for the development of mental disorders.
How to normalize stress biochemistry
Physical activity: increases dopamine and serotonin levels, reduces cortisol
Sleep: restores neurotransmitter balance
Meditation, breathing practices: reduce the activity of the sympathetic nervous system
Social support: reduces stress levels at the hormonal level
Rational nutrition: foods with tryptophan (nuts, bananas, eggs) increase serotonin
Psychotherapy: cognitive behavioral therapy helps change threat perceptions
The biochemistry of stress is body language that can be read. And while it’s not always possible to change the world around you, it is possible to influence your own response. That’s the power of stress science.
