8 December 2010 Renal Physiology Lab this week: Urinalysis Review website for instructions. Avoid caffeine on lab day, come to lab well hydrated. Exam options: Tuesday PM, Thursday AM, Friday AM

Fig. 14.02a 14.02a.jpg

Calculating clearance Clearance of s = Urine concentration of s X Urine Volume Plasma concentration of s “24 hour urine catch” + blood sample Special cases: Clearance of Inulin and creatinine (filtered only; use to measure Glomerular Filtration Rate.) Para Amino Hippurate (filtered and completely secreted, use to measure Renal Plasma Flow)

Clearance of Inulin is 120 ml/min Clearance = volume of plasma from which a substance is completely removed (cleared) by the kidneys per unit time. Clearance of Inulin is 120 ml/min Cinulin or Ccreatinine = Glomerular Filtration Rate If C x is greater than GFR ( which is Cinulin) then that substance undergoes NET TUBULAR SECRETION If C x is less than GFR ( which is Cinulin) then that substance undergoes NET TUBULAR REABSORPTION

Renal Handling Net Reabsorption Ex: Sodium Complete Reabsorption Ex: Glucose Net Secretion Ex: PAH & RPF

Reabsorption and secretion in proximal tubule is NOT under hormonal control. Primary active transport of Na+ establishes a gradient for reabsorption of glucose, amino acids, etc. Reabsorption and secretion in DCT & CD is under hormonal control. Hormones that act here: ANH, ADH, Aldosterone. Here, reabsorption of Na+ is linked to the secretion of K+.

Effect of Aldosterone: insertion of more Na+K+ATPase into basolateral membrane Effect: Increase Na+ reab and Increase K+ Secretion

Figure 14.30 Apply this information to each of the three Test Beverages used in the Urinalysis Lab! Cell in the adrenal cortex that respond to AII are also receptors for plasma K+ concentration. Sodium reabsorption and potassium secretion are coupled.

Effect of ADH: insertion of more aquaporins in th the membranes Effect: Increase H2O reabsorption

Figure 14.31 Normally, all filtered bicarbonate is “reabsorbed”