Changes

Steroids are 21-carbon, 4-ring molecules. Biologically active steroids have a double covalent bond between carbon atoms 4 and 5, and a ketone groups at C3. Substitutions to the molecule can change the nature of a steroid's activity.

Steroids are 21-carbon, 4-ring molecules, with biologically active steroids have a double covalent bond between carbon atoms 4 and 5, and a ketone groups at C3. The body endogenously produces steroids which are essential for life; they regulate a variety of functions under normal physiological conditions and have important roles in response to stress. These steroids are  produced in the adrenal cortex and are therefore known as "corticosteroids". The corticosteroids can be further divided to mineralocorticoids and glucocorticoids which are synthesised in different areas of the cortex. Mineralocorticoids (such as aldosterone) are produced in the zona glomerulosa; glucocorticoids include cortisol (from the zona fasiculata) and corticosterone (from the zona reticularis). There is some overlap in function of mineralo- and gluco-corticoids.

Endogenous corticosteroids are essential for life; they regulate a variety of functions under normal physiological conditions and also have effects when the body is under stress. All corticosteroids are produced in the adrenal cortex, but different sub-categories are synthesised in different areas of this. Mineralocorticoids, such as aldosterone, are produced in the zona glomerulosa. The glucocorticoids include cortisol (or hydrocortisone), which is produced in the zona fasiculata, and corticosterone from the zona reticularis.

Corticosteroids are synthesised from plasma cholesterol. This is stored in the adrenal gland and corticosteroids are assimilated and released as they are required.