Tubular fluid is the fluid in the tubules of the kidney. It starts as a renal ultrafiltrate in the glomerulus, changes composition through the nephron, and ends up as urine leaving through the ureters.
Composition table The composition of tubular fluid changes throughout the nephron, from the proximal tubule to the collecting duct and then as it exits the body, from the ureter.
+Concentration (mM) of substances in different segments of nephron and collecting duct systemSubstanceproximal tubuleloop of HenleDistal convoluted tubuleCollecting duct system S1 S2 S3 descending limb thin ascending limb thick ascending limb connecting tubule initial collecting tubule cortical collecting ducts medullary collecting ductsNa+ 142 Page 777 142 100 70 40
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