Renal and Urinary Systems/Electrolyte Balance

Abstract

Renal physiology involves the regulation of fluid balance and blood pressure, absorption of glucose, amino acids, and other small molecules, maintenance of acid-base balance; regulation of sodium, potassium, and other electrolytes; clearance of toxins; production of various hormones, such as erythropoietin, which is responsible for production of red blood cells in the bone marrow, and renin which helps to regulate the extracellular fluid and osmolality. (1,2) The physiology of the kidneys is studied at the level of smallest functional unit of the kidney, the nephron. The filtration process begins by the nephron filtering the blood entering the kidneys (glomerular filtration). This filtrate flows along the nephron to promote reabsorption of water and small molecules and the secretion of wastes from the blood into the urine (tubular reabsorption and tubular secretion). At the end the remaining filtrate goes to the collecting duct to enter the renal pelvis. From the renal pelvis, the urine passes to the bladder and is excreted to the exterior.(1-3) In order to work properly the kidney must receive adequate blood flow, any reduction of blood flow to the kidneys, can result in damage of the kidney structure that can be reversible or not. Multiple studies can provide a qualitative assessment of the renal function and also look for structural abnormalities.(1) This review has 6 figures, 5 tables, and 36 references Keywords: renal blood flow, glomerular filtration, Glomerular Filtration Rate (GFR), vasopressin, antidiuretic hormone, aldosterone, juxtaglomerular cells, chronic kidney disease, pathophysiology, diabetes mellitus