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Figure 1-1  A cross-section of the renal architecture
Figure 1-2  Major sections of the nephrons and their position within the cortex and medulla.
Figure 1-3  A cartoon of the nephron and its associated blood supply. The basic steps in urine formation are illustrated. 1. Filtration. 2. Reabsorption. 3. Secretion. 4. Excretion.

Figure 2-1  Pressure gradients and control points in the renal circulation. H.P. = hydrostatic pressure. p_b = colloid osmotic pressure.
Figure 2-2  Balance between hydrostatic and colloid osmotic pressures in the two capillary beds.
Figure 2-3 The filtration pathway.
Figure 2-4  Pressures involved in filtration.
Figure 2-5  Hydrostatic and colloid osmotic pressure profiles in the glomerular capillary bed.
Figure 2-6  Effect of factors altering pressures in the glomerular capillaries on mean filtration rate.
Figure 2-7  Effect of changes in afferent and arteriolar resistance on GFR and RBF.
Figure 2-8  The juxtaglomerular apparatus.
Figure 2-9  The juxtaglomerular apparatus is a major control point.
Figure 2-10  Autoregulation. The effect of changes in arterial pressure on RBF and GFR.
Figure 2-11  The tubuloglomerular feedback mechanism.
Figure 2-12  The effect of the autoregulatory mechanisms and PGE₂ on the response of the renal arterioles to extrinsic factors.

Figure 3-1  The basic structure of epithelial cell layers.  The width of the zonula occludens and the paracellular space have been greatly exaggerated for purposes of emphasis.
Figure 3-2  Changes in the urine to plasma concentration ratio (U_x/P_x) of various substances along the length of the nephron.  Note that the ordinate is a log scale.
Figure 3-3. Changes in the fraction of the filtered amount of substances remaining in the tubular fluid along the length of the nephron.
Figure 3-4. An example of the generation of a transepithelial electrical gradient by a tubular cell. 
Figure 3-5. An illustration of a gradient-limited transport system.

Figure 4-1. Measurement of filtration rate. 
Figure 4-2. Measurement of solute reabsorption rate.
Figure 4-3. Measurement of solute secretion rate.
Figure 4-4. Effect of plasma concentration of a substance on its clearance. A. Substance that is filtered only. B. Substance that is reabsorbed. C. Substance that is secreted.
Figure 4-5. The effect of changes in P_g on its rates of filtration, reabsorption, excretion and clearance.
Figure 4-6. Changes in plasma creatinine concentration and 1/P_cr as a function of changes in GFR.
Figure 4-7. Illustration of the utility of measuring P_cr in a patient with chronic renal disease.
Figure 4-8. Calculation of fractional water excretion.
Figure 4-9. Calculation of the fractional excretion of a solute, FE_s.

Figure 5-1. The effect changes in urine flow rate on the fractional excretion of urea.
Figure 5-2. Proximal tubule reabsorption and secretion of urate.
Figure 5-3. Transport mechanisms for glucose reabsorption in the proximal tubule.

Figure 6-1. The transepithelial chemical and electrical gradients along the length of the proximal tubule. TF/P = tubular fluid to plasma concentration ratio; V_t = transepithelial voltage gradient; A.A. = amino acids.
Figure 6-2. The mechanisms for Na reabsorption in the proximal tubule.
Figure 6-3. The mechanism for HCO₃ reabsorption in the proximal tubule.
Figure 6-4. Mechanisms for Cl reabsorption in the proximal tubule.
Figure 6-5. Water reabsorption in the proximal tubule.
Figure 6-6. Mechanisms for NaCl reabsorption in the thick ascending limb of the loop of Henle.
Figure 6-7. Mechanisms of NaCl reabsorption in the distal convoluted tubule.
Figure 6-8. Na+ and Cl- reabsorption by the principal cells in the collecting tubule.

Figure 7-1. The negative feedback mechanism that regulates the osmotic concentration of the extracellular fluid.
Figure 7-2. The relationship between the plasma osmotic concentration and plasma ADH concentration. The maximum effective concentration is that which causes the kidney to maximally concentrate the urine.
Figure 7-3. The mechanism of action of ADH on principal cells. V2 = vasopressin 2 receptor. Gs = stimulatory G protein, AC = adenylyl cyclase, AQ2 = aquaporin 2.
Figure 7-4. An illustration of the use of the countercurrent principle to conserve heat and improve the efficiency of a furnace. The thick arrows indicate the direction of heat flow.
Figure 7-5. The loop of Henle, the "countercurrent multiplier". The numbers indicate the osmotic concentration. The large circles to the right represent cross-sections of the medulla. Dlh, alh = descending and ascending limbs of Henle's loop.
Figure 7-6. The role of the distal tubule and collecting tubule in the countercurrent process. CD = collecting tubule.
Figure 7-7. The vasa recta, the "countercurrent exchanger". Dvr, avr = descending and ascending vasa recta.
Figure 7-8. Countercurrent concentration of urea by the vasa recta and inner medullary collecting tubules.
Figure 7-9. An illustration of the effect of an increase to flow on net Na reabsorption.

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