Hyponatremia
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…
SLC4 Sodium-Driven Bicarbonate Transporters
The SLC4 ( s o l ute c arrier 4) family is a group of a membrane proteins that share sequence homology and in general mediate the transport of bicarbonate….
Chemoreceptors, Breathing and pH
The regulation of acid–base balance depends on renal mechanisms that determine net excretion of acid or base and breathing mechanisms that alter the partial pressure of carbon dioxide (PCO 2…
Thirst and Vasopressin
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…
Biophysical Basis of Glomerular Filtration
Marcello Malpighi (1628–1694) discovered the renal corpuscle and proposed that each glomerular body embraces the ampullar extremity of a tubule to form a “glandular follicle”. Thereafter, progress toward understanding the…
Renal Cortical and Medullary Microcirculations: Structure and Function
Approximately 170 liters per day of glomerular filtrate is formed in the human renal cortex. Nephrons and collecting ducts perform the enormous task of reabsorbing ~99% of the filtrate while…
Aquaporin Water Channels in Mammalian Kidney
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…
Extrarenal Potassium Metabolism
Internal potassium homeostasis is defined as the regulation of potassium distribution between the intracellular and extracellular fluid compartments, as distinct from the net gain or loss of potassium from the…
Sodium and Chloride Transport: Proximal Nephron
The principal function of the proximal tubule is the reabsorption of some two-thirds to three-quarters of the glomerular filtrate. This means, primarily, reabsorption of Na + , Cl − ,…
Physiology and Pathophysiology of Hypertension
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,…
