LSS Urinary System
3. Explain the phenomenon of “splay” In reality, the plasma concentration at which glucose begins to be excreted in the urine (threshold) is NOT identical to the plasma concentration at which the maximum rate of glucose reabsorption is first reached. In fact, the former is normally substantially lower than the latter. This phenomenon is known as splay.
4. What is the normal plasma glucose concentration? 3.6-5.8 mmol/l 5. Name the common disorder in which the primary abnormality is nothing to do with renal function but can lead to significant amounts of glucose appearing in the urine Diabetes – dysfunction of insulin production/regulation from beta cells within islets of Langerhans in pancreas, which normally act in conjunction with glucagon to regulate plasma glucose concentrations. 6. In renal glycosuria, significant amounts of glucose are present in the urine as a result of renal defect. How do you think the graphs you have drawn in answer to question 2 will differ from normal in someone with this disorder? The defect may occur in the glucose co-transporters in the proximal convoluted tubule, therefore glucose reabsorption does not occur nearly as efficiently, and the rate of glucose reabsorption does not increase to combat an increased rate of glucose filtration glycosuria.
The Renal Cortico-Medullary Osmotic Gradient CAL Practical Session
The ability of the kidney to produce hypertonic urine depends on the high osmolarity of the interstitial fluid in the renal medulla. This in turn depends on three properties f the loops of Henle: 1. Countercurrent flow: down the descending limb and up the ascending limb 2. Descending limb: permeable to water; relatively impermeable to solutes 3. Ascending Limb: Water impermeable; NaCl actively transported out of the tubular fluid into the interstitium 32