Key renal physiology background – refresh your understanding

This resource is aimed at individuals who already have a textbook level understanding of renal physiology.  However, it’s always good to revisit your knowledge and understanding.  In this section, I will recap some basic, but key, renal physiology that will help you understand the clearance approach we will be reviewing.

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Key points:

1. The kidney is divided into outer (cortex) and inner (medulla) sections.
2. The functional unit is the nephron, which has a number of structural and functional sections.
3. Urine production is a process of filtration in the glomerulus, followed by modification of the filtrate down the nephron.
4. During filtration, 20% of the plasma moves from the glomerular capillaries into Bowman’s capsule, and then moves down the nephron.
5. The human glomerular filtration rate (GFR) is 125 ml/min (this is the total across both kidneys).  What do you think happens to GFR if you only have one kidney?
6. The modification process involves reabsorption (moving from the lumen of the nephron into the peritubular capillaries) and secretion (moving from the peritubular capillaries into the nephron lumen).
7. To understand renal physiology and pathophysiology we need to be able to measure GFR, and the transport and excretion of ions, solutes and water.
8. The clearance approach allows us to measure these.