الفهرس 
Physiology of Sodium and water balanceOnly 14 pages are availabe for public view
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Abstract
Various physiological mechanisms regulate sodium and water balance in the human body. These processes achieve acute and chronic sodium regulation and the simultaneous or sequential changes can be explained using a single physiological model. Steady intracellular water and osmolality is necessary for cell membrane integrity and cellular processes. Body fluids protect circulatory blood volume by altering Na+ and water balance. This is the most vital homeostatic function of the body. Changes in ECF volume are sensed by various cardinal sensors. Physiologically, the main aim of Na+ and water balance is to permit variable salt and water intake without large fluctuations in blood pressure or volume status. Homeostatic processes act in an integrated fashion to protect against any perturbations. Characteristically, these mechanisms are sequential as well as parallel. These may be synergistic or antagonistic to each other. Rapidity, sensitivity and potency of these powerful feedback systems differ. Various physiological and pathological insults determine the magnitude of response of these systems.
Hyponatremia is a common electrolyte disturbance encountered in the intensive care unit setting. The underlying etiology is multifactorial and includes processes that lead to both a baroreceptor-mediated and a baroreceptor independent increase in antidiuretic hormone release. Patients with hyponatremia have an increased mortality rate and therefore an understanding of the cause and treatment of this disorder is of paramount importance.
The association with hyponatremia and adverse outcomes could be the direct result of hyponatremia, the comorbidities that lead to the electrolyte derangement, or both. Whatever the mechanism, hyponatremia should not be viewed as an innocuous condition. Rather, clinicians should view this disorder with urgency and institute measures to prevent any further decline in the serum sodium concentration and initiate appropriate therapy for its correction.
The correct diagnosis and management of hyponatremia is complex and requires a systematic approach. Vasopressin receptor antagonists are potential tools in the management of hyponatremia. Further studies are needed to determine their role in the treatment of acute, severe, life-threatening hyponatremia as well as chronic hyponatremia.