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Aldosterone

ENDOCRINE PHYSIOLOCY

Blood volumc

Renal factors

Hyperkalemia    Cardiac factors

Fnhanc.es excretion ot potas$ium and

hydrogen ion

Aldosterone plays supportive role in raising blood pressure

Atrial naturetic peptide

Adrenal gl

Circulating blood Sweal gland Salhrary gland

Intestine-

J0HNA.CRAie_M3

Figurę 8.16 Actions of Aldosterone

The mineralocorticoid aldosterone plays an important role in regulat-ing the extrac ellular fluid {ECF) and blood volumes and in maintain-ing K" balance. When ECF and blood volumes are reduced (e.g., hemorrhage, diarrbca), ronin is released trom the kidney. which in tum inereases angiotensin II levels. Angiotensin II is a polent stimula-tor of aldosterone secretion by the adrenal gland. Aldosterone acts on a number of organs, causing the retention o i Na * and water, a response that serves to inerease ECF and blood volume. The kidney is the most important organ in this response (see Figures 6.12 and 6.14). When the ECF and hlood volurnes are inereased (e.g., conges tive heart failure), atrial natriuretie peptide is secreted and acts on the adrenal cortex to inhibit aldosterone secretion (see Figurę 6.13). An inerease in the |K*| of the ECF (hyper-kalemia) also stimulates aldosterone secretion by the adrenal cortex Aldosterone at is primarily on the kidney to stimulatc K‘ excretion (sec Figurę 6.15}. Finally, aldosterone inereases urinary H‘ excretion (see Figurę 6.17).

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