Understanding the Normal Stress Response of the body

<aside>

The normal response of our body to stress:

A. Activation of HPA axis

B. Sympathetic nervous system activation

</aside>

A. Activation of HPA Axis

Stress detection:

The hypothalamus is the initial region in the brain that responds to a stressor. It determines the severity of the stressor. In response, it releases corticotropin-releasing hormone (CRH) into the bloodstream, which acts on the pituitary gland to stimulate the release of adrenocorticotropic hormone (ACTH).

Cortisol release

ACTH acts on the adrenal cortex (outer part) and releases cortisol into the bloodstream. Cortisol is the most important component of stress response and it brings about the following effects on the body:

• Increases glucose availability by promoting gluconeogenesis and promotes glycogenolysis.
• Modulates immune response by reducing inflammation. However, prolonged exposure to cortisol suppresses the immune response.
• Increases sensitivity of BV to Nor-adrenaline to maintain BP
• Affects metabolism by promoting the breakdown of fats and proteins for energy use.

Feedback loop

Once cortisol reaches a certain level, it exerts negative feedback on the hypothalamus and pituitary gland, reducing the release of CRH and ACTH, which prevents excessive cortisol release.

B. Sympathetic nervous system activation

The sympathetic system stimulates the adrenal medulla to release catecholamines- primarily epinephrine and norepinephrine.

Epinephrine increases heart rate, increases blood flow to muscles, and increases glucose metabolism contributing to the body’s flight and fight response.

Norepinephrine increases BP and directs blood flow to critical areas, like muscles and the brain.

C. Other effects of Stress

Acute stress may result in the suppression of thyroid hormone release due to cortisol's inhibitory effects on the hypothalamus and pituitary.

Understanding the mechanism of Chronic Stress Response of the body

Hormonal balance in our body gets dysregulated due to chronic stress:

Cortisol imbalance:

• Flattened cortisol daytime production patterns and blunted release to stressors are observed. This results in:
• Increases cellular immunity resulting in increased production of proinflammatory cytokines such as tumor necrosis alpha (TNF-α), interleukin-6 (IL-6), and interleukin-12 (IL-12). It also suppression of anti-inflammatory mediators like IL-4 ,IL-10 ,and decreases lymphocyte function and disrupting T-cell signaling.
• It causes insulin resistance and increased abdominal fat. Individuals who regularly consume high glycemic foods and/or are insulin resistant will often experience a hypoglycemic “crash” after a meal which then triggers a rise in cortisol.

Altered HPA axis:

Elevation of baseline cortisol levels results in mood disturbances, anxiety, depression, and cognitive dysfunction.

Other hormones:

• Chronic suppression of the HPA axis results in reduced levels of sex hormones like estrogen, progesterone, and testosterone. This can result in menstrual irregularities in women, low libido, and fertility issues.
• It impairs the release of growth hormone and thyroid hormones, leading to metabolic disturbances and growth impairment in extreme cases.