Kidney Water Reabsorption Occurs. Reabsorption of water and specific solutes occurs to varying degrees over the entire length of the renal tubule. This principal is referred to as water follows.
The nephron removes water and also other solutes from the tubular fluid fluid that passes through the distal tubule and returns them to the capillary network. Occuring more commonly within the nephron system than filtration this is a form of active transport which takes the the useful substances for the body from the tubules and places them back into the blood filled capillaries. The structural and functional unit of the kidney is the nephron as shown below.
An increase in osmolality causes the gland to secrete antidiuretic hormone adh resulting in water reabsorption by the kidney and an increase in urine concentration.
Bulk reabsorption which is not under hormonal control occurs largely in the proximal tubule. The two factors work together to return the plasma osmolality to its normal levels. Sodium moves out of lumen into the epithelium by diffusion or by ion channels or by cotransport with glucose which is also being reabsorbed or countertransport with h ions which are being secreted. The structural and functional unit of the kidney is the nephron as shown below.