Describe renal handling of potassium (60% marks), including factors that may influence it (40% marks).
This question covers a core physiology topic. The detail required is well described in the recommended reference texts. Generally, this question was poorly answered. From an answer template perspective, a "describe question" in this context involves both the stating the relevant potassium handling mechanism and then giving a description of how it occurs and how this system is regulated. Many answers that scored poorly simply listed sites of potassium handling but excluded the details surrounding the specific receptors and channels involved as well as the processes that exist to perpetuate and regulate these biological processes. Simple identification as to whether the potassium was being secreted or reabsorbed as well as the location as to where this may occur within the nephron, were often not specifically detailed or used interchangeably. Such answers scored poorly.
Palmer, Biff F., and Deborah J. Clegg. "Physiology and pathophysiology of potassium homeostasis: core curriculum 2019." American Journal of Kidney Diseases 74.5 (2019): 682-695.
Wright, Fred S. "Sites and mechanisms of potassium transport along the renal tubule." Kidney international 11.6 (1977): 415-432.
Ludlow, M. "Renal handling of potassium." ANNA journal 20.1 (1993): 52-58.
Malnic, Gerhard, et al. "Regulation of K+ excretion." Seldin and Giebisch's The Kidney. Academic Press, 2013. 1659-1715.
De Rouffignac, C., and F. Morel. "Micropuncture study of water, electrolytes, and urea movements along the loops of Henle in Psammomys." The Journal of clinical investigation 48.3 (1969): 474-486.
Burg, Maurice B. "Thick ascending limb of Henle's loop." Kidney international 22.5 (1982): 454-464.
Ellison, D. H., H. Velazquez, and F. S. Wright. "Mechanisms of sodium, potassium and chloride transport by the renal distal tubule." Mineral and electrolyte metabolism 13.6 (1987): 422-432.
Subramanya, Arohan R., and David H. Ellison. "Distal convoluted tubule." Clinical Journal of the American Society of Nephrology 9.12 (2014): 2147-2163.
Nichols, C. G., K. Ho, and S. Hebert. "Mg (2+)‐dependent inward rectification of ROMK1 potassium channels expressed in Xenopus oocytes." The Journal of Physiology 476.3 (1994): 399-409.
Huang, Chou-Long, and Elizabeth Kuo. "Mechanism of hypokalemia in magnesium deficiency." Journal of the American Society of Nephrology 18.10 (2007): 2649-2652.
Young, DAVID B. "Quantitative analysis of aldosterone's role in potassium regulation." American Journal of Physiology-Renal Physiology 255.5 (1988): F811-F822.
Siani, Alfonso, et al. "Comparison of variability of urinary sodium, potassium, and calcium in free-living men." Hypertension 13.1 (1989): 38-42.