BRAINCAKESelective Reabsorption
The glomerular filtrate contains many substances the body needs. Selective reabsorption is the process in which useful substances are taken back from the filtrate into the blood, while waste products such as urea are left behind or only partly reabsorbed. It is selective because different substances are reabsorbed by different mechanisms and in different amounts.
Most reabsorption, about two thirds of the filtrate, happens in the proximal convoluted tubule. Further reabsorption of ions and water happens in the loop of Henle, distal convoluted tubule and collecting duct.
Substances are reabsorbed by several mechanisms:
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Key terms in this lesson
- glomerular filtrate
- The fluid formed when blood plasma is filtered out of the glomerulus into the Bowman's capsule, containing water, ions, glucose, amino acids and urea.
- efferent arteriole
- The blood vessel that carries blood away from the glomerulus of a nephron.
- water potential
- A measure of the tendency of water molecules to move out of a solution, which determines the direction of osmosis.
More in Homeostasis
- Osmoregulation
- Osmoregulation in Mammals
- Structure and Function of the Kidney
- Ultrafiltration
- Proximal Convoluted Tubule
- Loop of Henle
- Countercurrent Multiplier
- Distal Convoluted Tubule
All 41 lessons in Homeostasis · All Edexcel A-level Biology topics