Why are stressful moments so painful? - A guide on biology of stress!

 Human Brain

Stress and low phase in life are not only limited to thoughts and memories but get captured in our body through different mechanisms. Any kind of pain - physical or psychological manifests in the body via the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal axis (HPAA) of the endocrine (hormonal) system.

Social and emotional conditions impact like physical ones since psychological pain draws on many of the same neural networks as physical pain (Eisenberger and Lieberman 2004); this is why situations like a car cutting us off, getting rejected, getting a root canal and even just a worrisome thought trigger similar pains in the body.

Whenever the brain encounters anything as a source of threat, the amygdala sounds the alarm, cascading following reactions:

  • The thalamus wakes up the brainstem, which further releases norepinephrine, a neurotransmitter responsible for narrowing blood vessels and increasing blood pressure.
  • The SNS sends signals to different organs and muscle groups in the body, readying them for fighting.
  • The hypothalamus prompts the pituitary gland to signal the adrenal glands to release epinephrine (adrenaline) and cortisol, commonly known as “stress hormones”.

Within few seconds of above reactions, the brain and body light up like a Christmas tree and are on high alert. We start thinking of what’s going on in the body and are a little upset by now.

Epinephrine increases the heart rate and dilates the pupils (so the eyes can gather more light). Norepinephrine increases the blood pressure and pushes blood to large muscle groups. The lungs also dilate more in order to deal with heavy breathing.

Cortisol shuts the immune system to withdraw energy from healing of wounds. It increases amygdala activation and suppresses hippocampal activity which inhibits the amygdala; turning all brakes off the amygdala.

Other functions such as reproduction and digestion are also sidelined. Salivation decreases so the mouth starts to feel dry and we become constipated.

A worrisome thought intensifies and mobilizes the whole body and brain for action as if we’re running for cover from danger. SNS/HPAA arousal stimulates the amygdala, which is hardwired to focus on negative information and react intensely to it. Consequently, feeling stressed sets us up for fear and anger.

The activation of so many bodily systems helped the early man to survive given the harsh and physical and social environments that he lived in. But are we supposed to pay this unnecessary cost given our comfortable modern living? We live in a society that relies on nonstop SNS/HPAA arousal; unfortunately which is completely unnatural in terms of our evolutionary template.

 

Key words to remember

Sympathetic Nervous System - one of the two main divisions of autonomic nervous system. The autonomic nervous system functions to regulate the body's unconscious actions. The sympathetic nervous system's primary process is to stimulate the responses to harmful attack and threat.

Endocrine System - a group of ductless glands which regulate bodily processes by secreting hormones.

Amygdala - a part of the brain that responds particularly to emotionally charged and negative stimuli (Rasia-Filho, Londera, and Achaval 2000). A kind of siren for the brain.

Thalamus - a relay station for sensory information in the middle of the brain.

Hypothalamus - regulates hunger and sex and activates pituitary gland.

Hippocampus - forms new memories and detects threats; one of the few regions in the brain that can actually grow new neurons.

 

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1 comment

  • Wonderful.

    R.S. GUPTA

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