The blood that flows into the glomerulus under great pressure which is much greater than in the capillaries elsewhere, this high pressure causes the liquid part of the blood to filter out from the glomerulus into the renal tubule. This filtration under force is ultrafiltration. Therefore, the blood that comes out of the glomerulus is relatively thicker. The glomerular filtrate that enters the renal tubule is not urine. It is just an extremely dilute solution that contains several usable materials - glucose, salts such as sodium.
As this filtrate passes down into the tubule, more water is reabsorbed, however, keeping the concentration of blood in check.
This process is termed selective reabsorption. A Certain substance like Potassium ions and another large number of foreign chemicals including drugs like penicillin are passed into the forming urine in the distal convoluted tubule.
The uriniferous tubule is divided into the proximal tubule, the intermediate thin tubule, the distal tubule and the collecting duct. The present chapter is based on the chapters by Maunsbach and Christensen on the proximal tubule, and by Kaissling and Kriz on the distal tubule and collecting duct in the edition of the Handbook of Physiology, Renal Physiology.
It describes the fine structure light and electron microscopy of the entire mammalian uriniferous tubule, mainly in rats, mice, and rabbits. The structural differences along the uriniferous tubule strictly coincide with the distribution of the major luminal and basolateral transport proteins and receptors and both together provide the basis for the subdivision of the uriniferous tubule into functional subunits.
Data on structural adaptation to defined functional changes in vivo and to genetical alterations of specified proteins involved in transepithelial transport importantly deepen our comprehension of the correlation of structure and function in the kidney, of the role of each segment or cell type in the overall renal function,and our understanding of renal pathophysiology.
0コメント