BRAINCAKELoop of Henle
The loop of Henle is a hairpin-shaped section of the nephron that dips from the cortex down into the medulla and back up again. Its job is to create a region of high solute concentration (low water potential) in the tissue fluid of the medulla, so that water can later be reabsorbed from the collecting duct and concentrated urine can be produced.
The two limbs have different properties.
The descending limb is narrow, thin-walled and permeable to water, but relatively impermeable to sodium and chloride ions. As the filtrate flows down, water leaves by osmosis into the medulla, which has a low water potential. The filtrate becomes more concentrated, reaching its lowest water potential at the tip of the loop.
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Key terms in this lesson
- medulla
- The inner region of the kidney, containing the loops of Henle and collecting ducts.
- cortex
- The outer region of the kidney, containing the Bowman's capsules and convoluted tubules.
- vasa recta
- Blood capillaries running alongside the loop of Henle that carry away water without diluting the medulla.
More in Homeostasis
- Structure and Function of the Kidney
- Ultrafiltration
- Selective Reabsorption
- Proximal Convoluted Tubule
- Countercurrent Multiplier
- Distal Convoluted Tubule
- Collecting Duct
- Urine
All 41 lessons in Homeostasis · All Edexcel A-level Biology topics