Table of Contents
- 1 What is filtered reabsorbed and secreted?
- 2 Which ion is both secreted and absorbed by nephron?
- 3 What is the difference between filtration reabsorption and secretion?
- 4 Where is sodium filtered in the nephron?
- 5 Which material is secreted into the filtrate in the kidney tubule?
- 6 Where does tubular reabsorption and secretion take place?
- 7 How is the reabsorption of water regulated in the nephron?
What is filtered reabsorbed and secreted?
The filtrate absorbed in the glomerulus flows through the renal tubule, where nutrients and water are reabsorbed into capillaries. At the same time, waste ions and hydrogen ions pass from the capillaries into the renal tubule. This process is called secretion.
Which ion is both secreted and absorbed by nephron?
Learning Objectives
| Substances Secreted or Reabsorbed in the Nephron and Their Locations (Table 25.5) | |
|---|---|
| Substance | PCT |
| Sodium | 65 percent actively reabsorbed |
| Chloride | Reabsorbed, symport with Na+, diffusion |
| Water | 67 percent reabsorbed osmotically with solutes |
Is glucose filtered reabsorbed and secreted?
Material is also actively secreted depending on conditions in the body such as pH and potassium concentrations. The final concentrated urine passes through the ureters, into the bladder, and is excreted. D-glucose is filtered and almost completely reabsorbed under normal conditions.
Is sodium filtered reabsorbed and secreted?
Regulated reabsorption, in which hormones control the rate of transport of sodium and water depending on systemic conditions, takes place in the distal tubule and collecting duct. Even after filtration has occured, the tubules continue to secrete additional substances into the tubular fluid.
What is the difference between filtration reabsorption and secretion?
As the filtrate flows through the renal tubule, water, and essential solutes are returned into the blood through the process of reabsorption while excess ions and metabolic wastes are excreted into the urine through the process of secretion.
Where is sodium filtered in the nephron?
proximal nephron
The proximal nephron absorbs about two-thirds of filtered sodium, without dissociating salt and water absorption. The thick ascending limb absorbs 25% of filtered Na+, but no water. The distal nephron absorbs 10% of filtered Na+ in close relation with K+ and, to some extent, H+ secretion.
How is glucose filtered and reabsorbed?
Under normal circumstances, up to 180g/day of glucose is filtered by the renal glomerulus and virtually all of it is subsequently reabsorbed in the proximal convoluted tubule. This reabsorption is effected by two sodium-dependent glucose cotransporter (SGLT) proteins.
Is glucose actively reabsorbed?
Glucose is actively reabsorbed in the proximal convoluted tubule.
Which material is secreted into the filtrate in the kidney tubule?
Secreted substances largely include hydrogen, creatinine, ions, and other types of waste products, such as drugs. Tubular secretion is the transfer of materials from peritubular capillaries to the renal tubular lumen and occurs mainly by active transport and passive diffusion.
Where does tubular reabsorption and secretion take place?
Tubular secretion occurs mostly in the PCT and DCT where unfiltered substances are moved from the peritubular capillary into the lumen of the tubule. Secretion usually removes substances that are too large to be filtered (ex: antibiotics, toxins) or those that are in excess in the blood (ex: H +, K +).
What happens to filtered plasma when it is reabsorbed?
Less than 1% of the filtered plasma is excreted from the body. Hence, 99% is reabsorbed. Changes in the GFR can have a large impact on how much must be reabsorbed and GFR needs to be closely regulated. The GFR will change with MAP. Increases in MAP would cause an increase in GFR and vice versa.
How are substances secreted into the renal tubules?
In tubular secretion molecules move from the plasma into the renal tubules to become part of the filtrate. Secretion involves the same mechanisms as reabsorption except in reverse. Substances secreted include potassium, H ions, waste product s such as choline and creatinine and foreign substances such as penicillin.
How is the reabsorption of water regulated in the nephron?
Various portions of the nephron differ in their capacity to reabsorb water and specific solutes. While much of the reabsorption and secretion occur passively based on concentration gradients, the amount of water that is reabsorbed or lost is tightly regulated.