Which of the following is the principal site for regulation of fluid and electrolyte balance?

A) Cardiac system
B) Vascular system
C) Pulmonary system
D) Renal system

A balance of fluid and electrolytes is essential to maintain homeostasis.Excesses or deficits can lead to severe disorders.The kidneys are the principal regulator of fluid and electrolyte balance and are the primary source of fluid output.Specific hormones (e.g.,ADH,aldosterone)cause the kidneys to regulate the body's fluid and electrolyte balance.The heart and vascular system are involved in fluid balance but not in electrolyte balance and not as dramatically in fluid balance as are the kidneys-that is,they do not actually regulate electrolytes.The pulmonary system plays a major role in regulation of acid-base balance.