chapter  19
35 Pages

The renal system

The kidneys are organs specialized to filter the blood. As such, they make an important contribution to the removal of metabolic waste products as well as to maintenance of fluid and electrolyte balance. Specific functions of the kidneys include:

• Regulation of extracellular fluid volume • Regulation of inorganic electrolyte concentration in extracellular fluid • Regulation of the osmolarity of extracellular fluid • Removal of metabolic waste products • Excretion of foreign compounds • Maintenance of acid-base balance • Hormone and enzyme production

The

regulation of extracellular fluid volume

, in particular, plasma volume, is important in the long-term regulation of blood pressure. An increase in plasma volume leads to an increase in blood pressure and a decrease in plasma volume leads to a decrease in blood pressure. Plasma volume is regulated primarily by altering the excretion of sodium in the urine. Other

inorganic electrolytes

regulated by the kidneys include chloride, potassium, calcium, magnesium, sulfate, and phosphate.