1. The kidney consists of specialized vascular and tubular structures (the nephron) which collaborate in the production of urine:

a. The glomerular capillary is surrounded by an epithelial structure which forms the beginning of the tubule.

b. The afferent arterioles of every nephron are in close contact with the inner medullary collecting duct of the same nephron.

c. The vasa recta capillaries surround the proximal convoluted tubules.

d. The specialized macula densa at the junction between thick ascending limb of the loop of Henle and the distal tubule is in direct contact with the renal artery.

a) is Correct. The glomerulus is surrounded by the podocytes on the outside of the capillaries which transforms into the parietal epithelium which forms the Bowmans capsule, leading to the tubule.

b) all afferent arterioles are in cortex.

c). All vasa recta are in medulla.

d). Macula densa is in contact with its parent afferent arteriole.

2. A diagnostic renal clearance experiment is conducted and the following steady state (= equilibrium) measurements are obtained on a 34 year old male subject, weighing 60 kg (assume that the renal plasma flow (RPF) is the same as the effective renal plasma flow (ERPF):

Urine inulin = 200 mg/100ml

Plasma inulin = 4 mg/100ml.

Urine flow (V) = 2ml/min

Urine PAH = 1200 mg/100ml

Plasma PAH = 6 mg/100ml

200/4 x 2 ml/min =GFR= 100 ml/min.

ERPF = 1200/6 x 2 ml/min = 400 ml/min.

FF = GFR/ERPF = 100/400 = 0.25.

3. Any substance which is freely filtered at the glomerulus, is reabsorbed and is not secreted, will have a renal clearance that is: Choose one best answer.

A. Equal to the free water clearance during an antidiuresis.

B. Equal to the clearance of inulin.

C. Less than the clearance of inulin.

D. Greater than clearance of para aminohippuric acid (PAH).

E. The same as the creatinine clearance.

A fractional clearance (ratio of clearances of substance to inulin) < 1.0 indicates net tubular reabsorption of freely filtered substances.

4. An increased protein excretion (proteinuria) can indicate glomerular damage. Which of the following changes are likely to cause proteinuria? Choose 1 best answer:

A. An increase in glomerular water permeability

B. A fall in filtration surface area

C. Increased negative charge at the glomerulus

D. Loss of nephrin from the epithelial slit pore diaphragm

E. Increased proximal reabsorption of filtered protein.

D

Nephrin is an essential protein in the epithelial slot pore diaphragm and mutations are associated with heavy proteinuria.

a) And b) influence water not protein handling at the glomerulus.

b) And e) . More glomerular negative charge and more proximal tubule protein reabsorption would reduce urinary protein excretion.

5. Maintenance of a high glomerular filtration rate (GFR) is required for optimal kidney function. Which of the following options would be most likely to associate with a below optimal GFR in man?

A. High glomerular number at birth

B. A slow rate of rise of plasma protein concentration as blood flows through the glomerular capillary.

C. A low fluid pressure in Bowman’s space.

D. A high filtration fraction.

E. A low glomerular capillary water permeability.

Only e) is associated with low GFR (through low Kf).

6. A selective increase in renal plasma flow (RPF) due to parallel relaxation of the afferent and efferent arterioles leads to: Choose one best answer

A. A fall in glomerular blood pressure..

B. No change in GFR.

C. A rise in filtration fraction.

D. A rise in glomerular blood pressure.

E. A rise in GFR with no change in filtration fraction.

e). Parallel relaxation of afferent and efferent arterioles allows flow to increase (due to fall in renal vascular resistance) without a change in glomerular blood pressure or filtration fraction.

7. An increase in renal blood flow will lead to which of the following changes within the kidney: Choose one best answer

A. A fall in tubular fluid flow rate.

B. A fall in plasma flow through the peritubular capillaries.

C. An increase in plasma aldosterone concentration.

D. An increase in plasma angiotensin II concentration.

E. Increased total renal oxygen consumption but little change in the renal venous oxygen content (arterial – venous difference).

E

e): Increased RBF mans increases RPF and GFR. More Na filtered so more to reabsorb so total renal oxygen consumption will increase but because this is matched by the increased RBF, the oxygen extraction (A-V difference) across the kidney will stay about constant.

a). Filtration and tubule flow will increase

b) Peritubular capillary plasma flow will increase

c) and d). Increased renal blood flow is consistent with volume expansion, so aldosteroneand angiotensin II are suppressed

8. In which tubule segment is there active sodium reabsorption by the Na/K/2Cl (NKCC2) transporter but never any water reabsorption?

a. Proximal convoluted tubule

b. Descending limb of the loop of Henle

c. Thick ascending limb of the loop of Henle

d. Collecting duct

c) is correct.

a). water and Na are reabsorbed together in the proximal tubule. There is no NKCC2 in proximal tubule, only thick ascending limb of loop of Henle.

b). There is no active Na transport in the descending limb of the loop of Henle, and always passive water reabsorption..

d). There is active Na reabsorption in collecting duct (via ENaC) and also water reabsorption, if ADH is present.

9. The release of renin from the kidney, into the circulation is stimulated by:

a). Increased sodium delivery to the macula densa.

b). A small increase in the plasma potassium concentration.

c). A fall in renal perfusion pressure.

d). Increased sodium intake.

e). Plasma volume expansion.

c). Is correct. A fall in renal perfusion pressure is one of the volume depletion signals that stimulate renin release.

a), d) and e) are all consistent with volume expansion signals and these will suppress renin release. B). Plasma K+ does not regulate renin release, although an increase will stimulate aldosterone release by a direct action.

10. An extracellular fluid volume expansion leads to:

a) Increased aldosterone release.

b) Increased right atrial pressure

c) Activation of the sympathetic nervous system

d) Inhibition of nitric oxide production

e) Inhibition of atrial natriuretic peptide release.

b). Is correct. ECF volume expansion will raise right atrial pressure – signal to ANP release.

All the other options are consistent with ECF contraction.

11. A reduction in sodium excretion occurs when:

a) Nitric oxide is released by the tubules

b) The renal perfusion pressure increases abruptly

c) Glomerulotubular balance is disrupted and the fractional reabsorption of sodium falls.

d)  Septic shock occurs

e) The effective circulating volume is perceived as increased.

d). Is correct. When septic shock develops the perceived fall in circulating blood volume leads to excessive Na retention and therefore a fall in Na excretion.

a). NO inhibits Na reabsorption (increases UNaV).

b). Increased BP increases UNaV (pressure natriuresis).

c). a fall in fractional reabsorption will increase UNaV.

e). Increased volume increases UNaV.

12. An increased in renal sympathetic nerve activity will lead to which combination of changes:

a). Increased renal renin release and a fall in renal plasma flow.

b). Renal vasoconstriction and inhibition of tubular Na reabsorption.

c). Suppression of renal renin release and a constant GFR

d). Increased renal blood flow and increased active Na reabsorption in the thin ascending limb of the loop of Henle.

a). Is correct. Alpha adrenergic fibers stimulate renal arterioles and small arteries to vasoconstrict, lowering renal plasma flow. Beta adrenergic nerve fibes stimulate renin release from the granular cells in afferent arteriole.

b). Renal nerves stimulate tubular Na reabsorption in proximal tubule and TALH.

c). Renin release is stimulated and GFR will fall. d). Blood flow falls (due to renal vasoconstriction) and there is no active Na reabsorption in thin ALH.

13. An increase in antidiuretic hormone (ADH) release will occur when

a). Plasma osmolality increases by 2%

b). Blood volume falls by 2%

c). The plasma sodium concentration falls below normal

d). Renal blood flow increases

e). None of the above are correct.

a). is correct. When plasma osm increases by greater than ~ 1% above normal, ADH is released.

b). Blood volume has to fall by ~ 10% or more before ADH is released.

c). A fall in plasma Na lowers plasma osm, which will suppress ADH release.

d). Increased renal blood flow will not directly influence ADH release

14. A patient with nephrogenic diabetes insipidus is most likely to present with which combination of plasma and urine osmolality?

a). Normal plasma osmolality, low urine osmolality

b). High plasma osmolality, high urine osmolality

c). Low plasma osmolality, high urine osmolality

d). Low plasma osmolality, low urine osmolality

e). High plasma osmolality, low urine osmolality

e) is correct. Nephrogenic diabetes insipidus means the collecting duct cannot reabsorb water, so urine is dilute and plasma osm increases due to renal water loss.

15. ADH (antidiuretic hormone) stimulates the reabsorption of _________ and _________ in the kidney collecting ducts of a normal individual.

Choose 1 best answer:

a). Water and glucose

b). Sodium and glucose

c). Glucose and amino acids

d). Water and urea

e). water and phosphate.

d). Is correct.

a,b,c and e are wrong because: glucose, amino acids and phosphate are reabsorbed in the proximal tubule which is not controlled by ADH.

16. Urine concentration will increase when the following events occur:

a). Blood volume falls by 15%.

b). Decreased plasma osmolality

c). Increased proximal tubule reabsorption.

d). Decreased reabsorption of sodium from the thick ascending limb of the loop of Henle.

e). Increased vasa recta blood flow.

a). Is correct. When blood volume falls by >10% ADH is released in large quantities, water is retained and urine concentration increases.

b). Decreased plasma osm will suppress ADH release and produce a dilute urine.

c). Changes in proximal reabsorption have no impact on final urine concentration.

d) and e). Both cause a decreased medullary interstitial concentration gradient and therefore decreased urine concentration.

17. The primary regulation of renal potassium (K) excretion occurs in which segment?

a. Proximal tubule

b. Thin descending limb of the loop of Henle

c. Thick ascending limb of the loop of Henle

d. Distal convoluted tubule

e. Collecting duct

Answer e). K is reabsorbed in proximal tubule and TALH and usually secreted in the collecting duct (from the principal cells), unless the body needs to retain K in which case further reabsorption can occur in the collecting duct (via intercalated cells type A).

18. The kidney plays a role in maintaining calcium and phosphate balance in the body. Choose 1 best answer:

a). Approximately 99% of the filtered calcium is excreted in the urine.

b). Parathyroid hormone (PTH) inhibits tubular calcium reabsorption.

c). Activation of vitamin D to calcitriol occurs in the kidney and inhibits urinary phosphate excretion.

d). People with calcium containing kidney stones should never be given thiazide diuretics.

e). Patients with advanced chronic kidney disease usually have very low levels of plasma PTH.

C

c) is correct. The terminal hydroxylation step which activates Vitamin D to 1-25 dihydroxy vitamin D (calcitriol) takes place in the kidney, and calcitriol decreases tubular phosphate reabsorption (increases excretion).

a). ~ 99% filtered calcium is reabsorbed

b). PTH stimulates distal Ca reabsorption.

d). Thiazides are routinely prescribed to Ca stone formers, since they reduce Ca concentration in the distal tubule and collecting duct fluid.

e). Patients with CKD exhibit secondary hyper-parathyroidism.

19. In the kidney the long term maintenance of acid base balance is due to the renal excretion of H+ and replenishing of the bodies buffer stores. Renal hydrogen ion excretion has the following characteristics.

a. When aldosterone is present the secretion of H+ in the collecting duct is inhibited

b. Renal hydrogen ion secretion is directly stimulated when the PCO2 decreases.

c. Hydrogen ion secretion in the proximal tubules is responsible for most of the reabsorption of the filtered HCO3.

d. Hydrogen ion secretion in collecting duct occurs in the principal cells.

C

c). Is correct. H+ secreted into the proximal tubule lumen combines with filtered HCO3 which is converted to water and CO2. The CO2 diffuses into the cell and is re-formed to create H+ and HCO3 (which is reabsorbed).

a). Aldosterone stimulates collecting duct H+ secretion.

b). A fall in PCO2 makes the body fluids more alkaline, which inhibits renal H+ secretion.

d). H+ is secreted from the type A intercalated cells in the collecting duct.

20. In a normal person, a fall in plasma pH leads to:

a). A reduction in the rate of respiration.

b). A reduction in secretion of H+ by the collecting duct.

c). A reduction in proximal tubule bicarbonate reabsorption.

d). A rapid increase in H+ uptake by all the body buffer systems.

e). Nothing, as long as the plasma pH stays above 4.5 there is no problem.

D

d). Is correct. All the bodies buffers participate in buffering H+

a). A fall in plasma pH stimulates respiration to lower PCO2 and restore pH towards normal.

b). A fall in pamsa pH stimulates H+ secretion

c). A fall in plasma pH stimulates renal HCO3 reabsorption, to resteore pH towards normal.

e). If plasma pH falls below ~ 7.0 it is likely to be fatal

21. An hysterical patient at the dentist office is most likely to develop which of the following acid base disturbances:

Choose 1 best answer:

a). Mild chronic respiratory acidosis.

b). An acute respiratory alkalosis.

c). Metabolic alkalosis.

d). Acute respiratory acidosis.

e). Metabolic acidosis.

b). Is correct. Hysterical overbreathing causes PCO2 to fall very quickly which results in an acute respiratory alkalosis.

A), d) and e are all wrong because low PCO2 causes alkalosis.

c). Is wrong because the origin of the alkalosis is respiratory (primary effect on PCO2) not metabolic (primary effect on HCO3).

22. Advanced chronic kidney disease (CKD) can cause:

a). Salt sensitive hypertension.

b). Falls in plasma creatinine.

c). Increased hematocrit.

d). Metabolic alkalosis

a) Is correct. Due to our high Na diet, renal Na retention usually occurs in advanced CKD leading to hypertension. Dietary Na restriction is required.

b) GFR falls leading to increased plasma creatinine

c) Erythropoetin production falls leading to anemia.

d) The damaged kidney cannot adequately excrete H+ or make new HCO3, leading to a metabolic acidosis.