OCR A Biology
Loop Conc Na+ Cl Fluid Tissue Descending Medulla
The loop of Henle functions as a countercurrent multiplier, creating concentration gradients in the kidney medulla by actively transporting ions. The descending limb is permeable to water, becoming hypertonic, while the ascending limb actively pumps out ions, becoming hypotonic and concentrating the medullary tissue fluid, which ultimately allows for the formation of concentrated urine.
The loop of Henle functions as a countercurrent multiplier, creating concentration gradients in the kidney medulla by actively transporting ions. The descending limb is permeable to water, becoming hypertonic, while the ascending limb actively pumps out ions, becoming hypotonic and concentrating the medullary tissue fluid, which ultimately allows for the formation of concentrated urine.
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loop of henle |
| Back |
- it acts as countercurrent multiplier (uses energy to form conc gradients resulting in movement of substances)
- descending loop leads from PCT, conc of Na+ and Cl- in tissue fluid of medulla gets higher and higher moving from cortex to pyramids (due to activity of ascending limb of loop)
- filtrate entering descending limb of loop isotonic with blood, as it travels down, water enters tissue fluid via osmosis, it then moves down conc gradient into blood of surrounding cappilaries
- descending loop impermeable to Na+ and Cl- so no AT, fluid at bend is hypertonic to blood in capillaries
- first section of ascending loop very permeable to Na+ and Cl-, so diffuses out, then when filtrate isotonic to fluid, Na+ and Cl- actively pumped out into medulla tissue fluid (now high Na+ and Cl- concs in medulla tissue), ascending loop impermeable to water so it doesnt follow Na+ and Cl- down conc gradient, now filtrate hypotonic to blood and tissue fluid has high conc of ions (for kidney to form urine thats more conc than blood)
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OCR A Biology