Hypernatremia can occur with normal, increased or decreased total body sodium content. In healthy individuals and in normal conditions, the plasma concentration of sodium ranges between 136 and 143 mEq/l of plasma, despite large individual variations in the intake of…
Sodium and its accompanying anions are the principle osmotically active solutes in extracellular fluid. When extracellular osmolality is low, intracellular osmolality is equally low. Therefore, although there are exceptions (Table 44.1), hyponatremia is usually associated with hypoosmolality and dilution of…
Concentrated urine is produced through the generation of an osmotic gradient in the renal medulla. The gradient in the outer medulla is widely believed to be generated by means of a mechanism in which an osmotic pressure difference is amplified…
Thirst and the antidiuretic hormone, arginine vasopressin, are the principal elements of a powerful homeostatic system that regulates the “effective” osmotic pressure of body fluids. This variable, usually referred to as “tonicity,” must be important for survival since mechanisms to…
Hypernatremia can occur with normal, increased or decreased total body sodium content. In healthy individuals and in normal conditions, the plasma concentration of sodium ranges between 136 and 143 mEq/l of plasma, despite large individual variations in the intake of…
The term diuretic derives from the Greek diouretikos , meaning “to promote urine.” Although infusion of saline or ingestion of water would therefore qualify as being diuretic, the term diuretic usually connotes a drug that can reduce the extracellular fluid…
Abstract Normal blood pressure (BP) regulation involves the integrated actions of multiple cardiovascular, renal, neural, endocrine, and local tissue control systems. Chronic hypertension is a disorder of long-term BP regulation, although short-term BP control systems may also be affected. Abnormal…
Extracellular fluid (ECF) volume is determined by the balance between sodium intake and renal excretion of sodium. Under normal circumstances, wide variations in salt intake lead to parallel changes in renal salt excretion, such that ECF volume is maintained within…
Hormones which enhance sodium excretion, i.e., natriuretic peptide hormones, are very important for the maintenance of extracellu/lar fluid volume within a narrow range, despite wide variations in dietary sodium intake. This regulation occurs through a complex interplay of the antinatriuretic…
Many of the mediators and regulators of renal salt reabsorption have been identified from physiologic studies. The manner in which these individual elements function in the context of integrated physiology in vivo is best understood from the consequence of mutations…