Water reabsorption from the proximal convoluted tubule by:

(Osmosis): Ref: 719-G, 254-55-SL (652- Ganong 23rd)Water reabsorption from proximal convoluted tubule - obligatory reabsorption of waterWater reabsorption from distal convoluted tubule and collecting duct - Facultative reabsorption of water* PCT is highly permeable to water, However water reabsorption is secondary (obligatory) to sodium reabsorption, when sodium is reabsorbed from the tubule, the osmotic pressure in the fluid present in lumen is reduced. This causes osmosis of water* Normally the DCT and CD are not permeable to water, but in the presence of ADH, these segments become permeable to water. So water is reabsorbed from the DCT and CD. This type of reabsorption in the presence of ADH is called facultative reabsorption.Countercurrent exchange is a passive process: 117-GFacilitated diffusion: - The transport, although occurring via a carrier, occurs in such a way that the solute molecules moves from a region of higher concentration to a region of lower concentration. In our body glucose moves from ECF into the cytoplasm via-this process Examples. Insulin helps the facilitated diffuse of glucose from ECF to ICF.