WSU BIOLOGY 251 - Topic 21 (6 pages)

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Topic 21

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Topic 21-the urinary system: reabsorption, secretion, and urine concentration


Lecture number:
21
Pages:
6
Type:
Lecture Note
School:
Washington State University
Course:
Biology 251 - Introductory Human Physiology
Edition:
1

Unformatted text preview:

BIO 251 1st Edition Lecture 21 Outline of Last Lecture I Overview a Function b Components c Kidney structure d Nephron structure e 3 basic renal processes f II Important notes Glomerular filtration a Process of filtration b Problem of GFR BP c Intrinsic regulation d Extrinsic regulation Outline of Current Lecture I Tubular reabsorption a Process b Reabsorption of Ba in proximal tubule c Reabsorption of Na in distal tubule d Reabsorption of substances via Na dependent secondary active transport These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute e Reabsorption of substances via Na dependent passive processes f II Reabsorption of phosphate Tubular secretion a H b K c Waste ions III Urine concentration a Countercurrent multiplication b Controlling urine concentration Current Lecture I Tubular Reabsorption A Introduction 1 Highly selective process a Need to get essential materials out of tubules and back in blood b Most wastes other than urea are too big to be reabsorbed and so are excreted in the urine 2 Examples of reabsorption rates Table 18 1 a 99 of filtered water 47 gallons day b 100 of filtered sugar 2 5 pounds day c 99 5 of filtered salt 0 36 pounds day B Process of Reabsorption Transepithelial Transport 1 Reabsorption requires molecules to cross two membranes apical membrane and basolateral membrane Fig 18 13 2 Two types of reabsorption Fig 18 14 a active at least one of the steps requires energy Fig 18 14a b passive none of the steps requires energy Fig 18 14b c C Reabsorption of Na in the Proximal Tubule Fig 19 14a 1 Na uses facilitated diffusion to cross apical membrane going down concentration gradient from tubular lumen into proximal tubule epithelial cell Can do so either by cotransport with glucose or an amino acid or by counter transport with H 2 Na actively crosses basolateral membrane using the Na K ATPase pump which moves Na against concentration



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