Explain The Adrenal Gland
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The paired adrenal or suprarenal gland are yellow, caplike,roughly triangular, flattened gland situated ate the cranial pole of each kidney. They measure about 5 by 3 by 1 cm and together weight about 15 gm. Each gland is surrounded by an envelop of areolar tissue having adequate amount of fat. Each Gland is differentiated into two parts which are different from each other in their origin structure and function. The outer brighter part is called cotrtex while the inner part is know as medulla. The outer surface of cortex is bright yellow but its inner part is brownish red in color . on the outer hand medulla is grey in color.
cortical part of adrenal gland originates from the embryonic mesoderm. This part is essential to life. and differentiated into three regions.
- outer thin zona glomerulosa whose small polyhedral cell are arranged in dense circular bunches
- central zona fasciculate the large polyhedral cell of which are arranged in parallel rows
- Inner Zona reticularis the spherical cells of which are arranged in branched row and from netlike structure.
Hormones of adrenal cortex and their functions:-
All the hormones secreted from adrenal cortex are fat soluble steroids called corticosteroids or adrenocorticoids. Most of the steroid have alcohol side chain therefore they are generally called sterols. Corticosteroids have been classified into following three groups
These hormones are secreted by the cells of the zonz golmerulosa of the corlical region of adrenal gland. Hormones of this group include aldosterone, corticosterone and deoxycorticosterone. Out of these corticosterone and deoxycorticosterone. out of these aldosterone is secreted in largest amount (90-95%).
Glucocorticoids are secreted by the cell of zone fasciculata part of the adrenal cortex. Principal glucocorticoids are cortisone, hydrocortisome and corticosterome out of these corticosterone is included in the category of mineralocorticoids also. Hydrocortisone is secreted in largest amount (about 95%) This is also known as cortisol.
Sex Hormones are secreted by the cells of middle zone fasciculata and inner zona reticulris part of adrenal cortex. The cell of these regions produce very small amount of male hormones are androgens and minute amount of female hormones or estrogens.