Chapter 5 ( Renal And Acid-Base Physiology )

Question 1

Clearance of a substance equation ?

Answer 1

Clearance = ( urine concentration x urine volume ) / plasma concentration

Question 2

Vasodilators of the renal arterioles ?

Answer 2

Prostaglandins E2 
Interleukin 2
Bradykinin 
Nitric oxide 
Dopamine

Question 3

ANP action on renal arterioles ?

Answer 3

Vasoconstriction of efferent arterioles
Vasodilatation of afferent arterioles
Which leads to increased RBC and GFR

Question 4

Mechanisms of autoregulation of RBF ?

Answer 4

1- Myogenic mechanism : by stretch receptors in the wall of renal afferent arterioles
2- Tubuloglomerular feedback : by sensation of the macula densa of increased load of NaCl

Question 5

Renal plasma flow equation ?

Answer 5

Equals the clearance of PAH which

= ( urine concentration of PAH x urine volume ) / plasma concentration of PAH

Question 6

Renal blood flow equation ?

Answer 6

RBF = RPF / ( 1- hematocrit )

Question 7

GFR equation ?

Answer 7

Equals the clearance of Inulin which =

( urine concentration of inulin x urine volume ) / plasma concentration of inulin

Question 8

Filtration fraction equation ?

Answer 8

FF = GFR / RPF

Question 9

What restricts plasma proteins filtration in nephrons ?

Answer 9

Anionic glycoproteins lining the filtration barrier

Question 10

Glucose threshold ? Tm ? Splay range ?

Answer 10

Threshold : plasma concentration of 250 mg/dL
Tm : plasma concentration of 350 mg/dL
Splay range : plasma concentration of 250-350 mg/dL

Question 11

Compounds that compete for the non-specific organic anion secretion system that PAH uses ?

Answer 11

Penicillin
Furosemide
Acetazolamide
Salicylate

Question 12

Equation to measure the fraction of the filtered water that has been reabsorbed ?

Answer 12

= 1 - ( 1 / [TF/P]inulin )

Question 13

How to know the fraction of the filtered load remaining at any point along the nephron ?

Answer 13

[TF/P]substance / [TF/P]inulin RATIO

Question 14

Acetazolamide mechanism ?

Answer 14

Carbonic anhydrase inhibitor ( diuretic ) that act in the early proximal tubule by inhibiting reabsorption of filtered HCO3-

Question 15

Early Proximal tubule reabsorption ?

Answer 15

67% of Na and water
All of glucose , amino acids and HCO3-
Some phosphate and lactate

Question 16

Late proximal tubule reabsorption ?

Answer 16

Na with Cl

Question 17

Reabsorption of the thick ascending limb of loop of Henle ?

Answer 17

25 % of Na
Contains Na-K-2Cl cotransporter in the luminal membrane
Impermeable to water so TF/P Na and TF/P osm are < 1 therefore its called the Diluting Segment

Question 18

Mechanism pf action of loop diuretics ?

Answer 18

Inhibiting the Na-K-2Cl cotransporter in the thick ascending limb of loop of Henle

Question 19

Reabsorption of early distal tubule ?

Answer 19

NaCl by Na-Cl cotransporter

Impermeable to water so its called the Cortical Diluting System

Question 20

Mechanism of thiazide diuretics ?

Answer 20

Inhibiting Na-Cl cotransporter in the early distal tubule

Question 21

Function of principal cells in the late distal tubule and collecting duct ?

Answer 21

1-Reabsorb Na and H2O
2-Secret K
3-Site of action of Aldosterone which increases Na reabsorption and K secretion
4-Site of action of ADH which increases H2O permeability by directing the insertion of H2O channels in the luminal membrane

Question 22

Functions of alpha-intercalated cells in late distal tubule and collecting duct ?

Answer 22

Secret H+ by an H+ ATPase

Reabsorb K by an H+,K ATPase

Question 23

Causes of shift of K into cells ?

Answer 23

Insulin
Beta adrenergic agonists
Alkalosis
Hyposmolarity

Question 24

Causes of shift of K out of cells ?

Answer 24

Insulin deficiency 
Beta adrenergic antagonists 
Acidosis 
Hyperosmolarity 
Inhibitors of Na-K pump ( ex: digitalis ) 
Exercise 
Cell lysis

Question 25

Causes of increased distal K secretion ?

Answer 25

``` High K diet Hyperaldosteronism Alkalosis Thiazide and loop diuretics Luminal anions ```

Question 26

Causes of decreased distal K secretion ?

Answer 26

Low K diet Hypoaldosteronism Acidosis K sparing diuretics

Question 27

Mechanism of action of K sparing diuretics ?

Answer 27

Spironolactone : aldosterone antagonist | Triamterene and Amiloride : act directly on the principle cells causing decrease K secretion

Question 28

ADH action on renal regulation of urea ?

Answer 28

Stimulates a facilitated diffusion transporter for urea (UT1) in the inner medullary collecting ducts , urea reabsorption from inner medullary collecting ducts contributes to urea recycling in the inner medulla and to the addition of urea to the corticopapillary osmotic gradient

Question 29

PTH action on renal regulation of phosphate ?

Answer 29

Inhibits phosphate reabsorption in the proximal tubule by activating adenylate cyclase , generating cAMP and inhibiting Na-phosphate cotransport , therefore PTH causes phosphaturia and increase urinary cAMP .

Question 30

Product of phosphate buffering H+ ?

Answer 30

H2PO4- ( Titratable acid )

Question 31

Loop diuretics effect on renal regulation of Ca ?

Answer 31

Inhibit Na reabsorption which in turn inhibits Ca reabsorption , as Ca reabsorption is coupled to Na reabsorption in the loop of Henle . If the volume is replaced , loop diuretics can be used in ttt of hypercalcemia

Question 32

Thiazide diuretics effect on renal regulation of Ca ?

Answer 32

Increases Ca reabsorption in early distal tubule , and therefore decrease Ca excretion . Its used in ttt of idiopathic hypercalciuria

Question 33

PTH effect on renal regulation of Ca ?

Answer 33

Increases Ca reabsorption by activating adenylate cyclase in the distal tubule

Question 34

How the corticopapillary osmotic gradient is maintained ?

Answer 34

By countercurrent exchange in the vasa recta

Question 35

Equation of free water clearance ?

Answer 35

C H2O = V - C osm | Cosm = (U osm x V) / P osm

Question 36

CO2

Answer 36

33 - 45

Question 37

HCO3-

Answer 37

22-28

Question 38

Examples for fixed acids ?

Answer 38

``` Sulfuric acid Phosphoric acid Ketoacids Lactic acid Salicylic acid ```

Question 39

Extracellular buffers and their pK ?

Answer 39

HCO3- pK : 6.1 | HPO4-2 pK : 6.8

Question 40

Intracellular buffers ?

Answer 40

Organic phosphates Ex : AMP, ADP , ATP , DPG Proteins Ex : Hemoglobin ( deoxy is better than oxy )

Question 41

Henderson-Hasselbalch equation to calculate pH ?

Answer 41

pH = pK + log ( A- / HA )

Question 42

Winter’s equation ?

Answer 42

Pco2 = (1.5 x HCO3-) + 8 +-2

Question 43

Unmeasured anions thats responsible for the anion gab ?

Answer 43

Phosphate Sulfate Citrate Proteins

Question 44

Normal range of anion gab ?

Answer 44

8-16 mEq/L

Question 45

Mechanism of different types of renal tubular acidosis ?

Answer 45

Type l : failure to excrete titratable acid and NH4 Type ll : renal loss of HCO3- Type lV : hypoaldosteronism —> hyperkalemia —-> increased K-H exchange —-> decreased H in urine and decrease formation of NH4 —-> accumulation of NH3 in urin ——> increased intracellular NH3 due to failure of its secretion —-> inhibition of further synthesis of NH3 in tubular cells

Question 46

Percentage of Phosphate excreted in the urine ?

Answer 46

15 % | Only 85 % is reabsorbed in proximal convoluted tubule , maybe less under action of PTH ( inhibits Na - P cotransport )

Question 47

Action of Angiotensin ll on the kidney ?

Answer 47

Increases Na-H exchange and HCO3 reabsorption from proximal convoluted tubule