Cortisol

Cortisol (hydrocortisone, C₂₁H₃₀O₅, ), is a corticosteroid hormone synthesized in the zona fasciculata of the cortex of the adrenal glands. Its systematic name is 11ß,17,21-Trihydroxypregn-4-ene-3,20-dione and its CAS number is 50-23-7.

The amount of cortisol present in the serum undergoes diurnal variation, with the highest levels present in the early morning, and lower levels in the evening, several hours after the onset of sleep. Serum cortisol levels fluctuate in response to a number of other variables, including ACTH levels, psychological stress, and such physiological stressors as hypoglycemia, illness, fever, trauma, surgery, fear, pain, physical exertion or extremes of temperature.

Cortisol is usually released in response to long term stress. Some effects of cortisol being secreted into the bloodstream are an increase in blood pressure and glucose concentrations. Also it increases the glycogen formation in the liver. (Freeman, 853) The release of cortisol inhibits functioning of the immune system, and bone formation.

Cortisol also inhibits the secretion of corticotropin releasing hormone (CRH), resulting in feedback inhibition of ACTH secretion. This normal feedback system is overridden in situations of stress.

Most serum cortisol, all but about 4 percent, is bound to proteins including corticosteroid binding globulin, CBG, and albumin. Only free cortisol is available to most receptors.

As an oral or injectable drug, cortisol is used medically in the treatment of anaphylaxis and other severe allergic reactions, and to reduce certain forms of swelling or edema.

References

• Freeman, Scott (2002). Biological Science. Upper Saddle River, Prentice Hall Inc.

Related topics

Post-traumatic stress disorder, HPA axis, Cushing's syndrome