Widely known as the body’s main stress hormone, we have all heard about cortisol at some point in our lives. Whether it was in an article about enhancing our performance or whether we were taught about its importance during biology lessons, those settings strongly advised that both high cortisol levels and cortisol deficiencies herald unfortunate unravelings for the human body.
In the beginnings of humankind, survival mechanisms were salient to ensure that individuals were able to protect themselves in life or death instances. The near-instantaneous secretion of the most dominant glucocorticoid (steroid hormone which regulates glucose metabolism and synthesis in the adrenal cortex; glucose+cortex+steroid) in humans, the hormone cortisol, had a notable role in the body’s reactions evolvement to stressful situations into what is known as the “fight or flight” response. This sequence of hormonal changes and physiological responses enables humans and other mammals to either fight off the danger or completely flee from threats.
Beside the stress controlling role it is commonly associated with, cortisol can play many other important parts, such as controlling blood sugar and pressure, reducing inflammation or helping the body use food for energy. Although, as people have been in a constant and unending evolution, and as the surrounding world has taken a complete turn for the better, cortisol secretions oftentimes occur in instances where not only do we not find ourselves in a life-threatening situation, but we are simply overreacting the stressors with daily issues such as school or work pressure, traffic jams, family problems and many others.
The endocrine response of secreting cortisol takes place in the hypothalamic-pituitary-adrenal axis (HPA axis), beginning in the hypothalamus, the component of the brain which has a vital role in coordinating physiological responses from organs and maintaining homeostasis (the state of balance between the body’s systems). In this first part of the HPA axis, a hormone called corticotropin-releasing hormone (CRH) is synthesized, which activates the release of adrenocorticotropic hormone (ACTH) in the pituitary gland. From then on, ACTH enters the bloodstream and activates pathways in the adrenal cortex (the outer layer of the adrenal gland, situated on top of the kidneys) to produce cortisol. After it is synthesized, cortisol spreads in the bloodstream, thus maintaining a state of high alert. The aftermath of cortisol release seriously impacts in a negative sense a big proportion of the body’s normal proceedings; hyperglycemia (pancreas), decreased amino acid uptake (muscles), gastric acid secretion (stomach), reduced calcium absorption (intestine), formation of glucose (liver), etc.
HYPOTHALAMUS → CRH → PITUITARY GLAND → ACTH → ADRENAL CORTEX → CORTISOL → BLOODSTREAM
Chronic stress, the over-stimulation of cortisol for an extended amount of time, can have detrimental effects in the brain and central nervous system. Hypercortisolism, also known as “Cushing syndrome” is caused by the overproduction of ACTH, a factor which stimulates the adrenal cortex to produce cortisol in excess. This complication usually occurs when pituitary adenomas (non-cancerous tumors) confuse the gland to synthesize more ACTH than necessary. The main symptoms of the disease are weight gain, easily-bruised and frail skin, reduced fertility, the appearance of a fatty lump between the shoulders and depression. If not treated properly, it leads to infections throughout the body, hypertension and osteoporosis (loss of bone tissue).
However, the insufficient production of cortisol in the adrenal glands called hypocortisolism, Addison’s disease or adrenal insufficiency, refers to the complications that occur when there is a deficit of the stress hormone, as well as of another hormone, aldosterone. Hard to discover, hypocortisolism’s symptoms span on an indefinite period of time and among the most severe ones are unintended weight loss, hypoglycemia, extreme fatigue and irritability. The only treatment provided for this health complication is the replacement of the missing hormones in the patient’s body through medicine.
To conclude, cortisol has an irreplaceable function in the body’s homeostasis, aiding our stress response system and fulfilling many essential roles throughout different organs.
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