Steroids

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 group 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). Corticosteroids are synthesised from plasma cholesterol which is stored in the adrenal gland and assimilated to corticosteroids as they are required. Endogenous glucocorticoid levels are regulated by the hypothalamus-pituitary adrenal axis, whereas the renin angiotensin aldosterone system controls mineralocorticoid levels.