Renal System Pt. 2

Question 1

Indicates the volume of plasma cleared of a substance per unit time (ml/min or ml/24hr)

Answer 1

Renal clearance

Question 2

How do you calculate renal clearance?

Answer 2

C = (U x V)/ P

U= urine concentration
V= urine flow rate
P= plasma concentration

Question 3

RBF is _____ proportional to the pressure difference b/w renal artery & renal vein, & is _____ proportional to the resistance of the renal vaculature

Answer 3

Directly; inversely

Question 4

_______ of renal arteriols (dopamine) —> increase in RBF

Answer 4

Vasodilators

Question 5

_____ & _____ constrict efferent arterioles —> increase GFR “protective”

Answer 5

Sympathetic stimulation & Angiotensin-II

Question 6

Myogenic mechanism

Answer 6

⬆️ bloof flow - ⬆️ stretch in afferent arteriole —> increase entry of Ca into vascular smooth muscle —> vasoconstriction —> maintain constant blood flow

Question 7

Tubuloglomerular feedback

Answer 7

⬆️ blood flow - ⬆️ fluid rush to macula densa - vasoconstriction of afferent arteriole —> maintain constant blood flow

Question 8

Excess fluid retention by kidneys
Acute or chronic kidney failure
Glomerulonephritis
Mineralocorticoid excess
Decreased arteriolar resistance (vasodilators)
Increased venous pressure (CHF, venous obs, cirrohsis)

Answer 8

High capillary hydrostatic pressure

Question 9

Low oncotic pressure
Loss of proteins (burns, wounds, nephrotic syndrome. Gastroenteropathy)
Failure to porduce proteins (malnutrition “kwashiokor”, cirrhosis, hypoalbuminemia)

Answer 9

Decreased plasma proteins

Question 10

Immune reactions (histamine)
Toxins
Burns
Prolonged ischemia
Vitamin deficiency (vit C)
Pre-eclampsia & eclampsia

Answer 10

Increased capillary permeability

Question 11

Cancer cells
Surgery
Infections (filariasis or elephantitis)

Answer 11

Blockage of lymphatics

Question 12

⬇️ ADH
⬇️ serum osmolarity/ serum Na
Hyposomotic urine
High urine flow rate

Answer 12

Primary polydipsia

Question 13

⬇️ ADH
⬆️ serum osmolarity/ serum Na
Hyposomotic urine osmolarity
High urine flow rate

Answer 13

Central DI

Question 14

⬆️ ADH
⬆️ serum osmolarity/ serum Na
Hyposmotic urine osmolarity
High urine flow rate

Answer 14

Nephrogenic DI

Question 15

⬆️ ADH
High/normal serum osmolarity/ serum Na
Hyperosmotic urine osmolarity
Low urine flow rate

Answer 15

Water deprivation (lost in desert)

Question 16

⬆️ ⬆️ ADH
⬇️ serum osmolarity/ serum Na
Hyperosmotic urine osmolarity
Low urine flow rate

Answer 16

SIADH

Question 17

What does activation of the macula densa do when decreased Na is delivered to DCT?

Answer 17

Vasodilation of afferent arteriole -> Increase GFR

It also stimulates Jexta cells

Question 18

The first and fastest line of defense against a change in H concentration acting within seconds

Answer 18

Buffer system
Extracellular = bicarb
Intracellular = Hgb

Question 19

The second line of defense acting within minutes

Answer 19

Respiratory compensation

Question 20

The third line of defense acting within hours to days

Answer 20

Renal compensation

Question 21

Only _____ & ______ can be completely compensated

Answer 21

Respiratory acidosis & resp alkalosis

Question 22

Anion gap = ? Normal range?

Answer 22

= Na - (Cl + HCO3)

8-16 mEq/L

Question 23

Why does HCO3 decrease in metabolic acidosis?

Answer 23

It is used to buffer the extra fixed acid

Question 24

How does renal compensate for metabolic acidosis? For chronic met acidosis?

Answer 24

1) Increased excretion of the excess H as titratable acid and NH4
2) Increase reabsorption of HCO3
For chronic: adaptive increase in NH3 to aid in excretion of excess H

Question 25

Umeasured anions

Answer 25

Phosphate, citrate, sulfate, & proteins

Question 26

The serum anion gap is _____ if the concentration of an unmeasured anion is increased to replace HCO3

Answer 26

Increased

Question 27

The serum anion gap is _____ if the concentration of Cl is increased to replace HCO3

Answer 27

Normal

Question 28

How does renal compensate for metabolic alkalosis?

Answer 28

Increased excretion of HCO3 bc the filter load of HCO3 exceeds the ability of renal tubules to reabsorb it

Question 29

If metabolic alkalosis is accompanied by _____ the reabsorption of HCO3 increases, worsening the metabolic alkalosis

Answer 29

ECF volume contraction (vomiting); Contraction alkalosis

Question 30

Why does low Ca cause tetany (alkalosis)?

Answer 30

Hypocalcemia increases the permeability of Na, getting closer to the threshold for action potential

Question 31

Causes of high anion gap metabolic acidosis

Answer 31

``` Methanol Uremia DKA Propylene glycol Iron tab or INH Lactic acidosis Ethylene glycol Salicylate/Sepsis/Starvation ```

Question 32

Cause mixed metabolic acidosis and respiratory alkalosis

Answer 32

Salicylate

Question 33

Causes of normal anionic gap metabolic acidosis

Answer 33

Loss of bicarb (diarrhea MCC) or Decreased renal excretion of acids (renal tubular acidosis & Addison’s)

Question 34

Distal RTA= inability to excrete H and therefore regenerate HCO3

Answer 34

Type I

Question 35

Proximal RTA= inability to reabsorb filtered HCO3 (complication of Fanconi’s syndrome)

Answer 35

Type II

Question 36

RTA= “hyporenin hypoaldosterone” Low aldosterone impairs K & H secretion -> hyperkalemic non-anionic gap acidosis Failure to excret NH4 Seen in diabetes d/t destruction of juxta cells Mild renal insufficiency

Answer 36

Type IV

Question 37

MCC of metabolic alkalosis

Answer 37

Volume & chloride depletion

Question 38

How does renal compensate for metabolic alkalosis?

Answer 38

By conserving Na (and Cl) and exchanging with H secretion

Question 39

In hypovolumia kidneys avidly reabsorb NaCl and pee out H. This means urinary chloride is ____ and the alkalosis _____ to NaCl repletion

Answer 39

Low; responds

Question 40

In the case of hyperaldosteronism (Na reabsorption/H excretion) & hypokalemia (K conserved/H excreted), urinary chloride is ____ and the alkalosis _____ to NaCl repletion

Answer 40

Normal; does NOT

Question 41

____ urinary Cl = hypovolumia (dry); | ____ urinary Cl = Hypokalemia, hyperaldo (Conn’s)

Answer 41

Decreased; normal

Question 42

A carbonic anhydrase inhibitor that inhibits the reabsorption of HCO3 in the ______. Weak diuretic properties

Answer 42

Acetazolamide; PCT

Question 43

Loop diuretics inhibit the Na/K/2Cl cotransport in the _______ resulting in retention of Na, Cl, & water in the tubule These drugs are the most efficacious of the diuretics.

Answer 43

Ascending LOH; Bumetanide, Furosemide, Torsemide, Ethacrynic acid

Question 44

Inhibit reabsorption of Na and Cl in the _____ resulting in retention of water in the tubule. Most commonly used diuretics.

Answer 44

thiazides; DCT

Question 45

An aldosteron antagonist, inhibits the aldosterone-mediated reabsorption of Na and secretion of K

Answer 45

Spironolactone (collecting tubule & duct)

Question 46

Block Na channels

Answer 46

Amiloride & triamterene (collecting tubule & duct)

Question 47

MOA of acetazolamide

Answer 47

Increases Na excretion d/t decreased Na/H exchange

Question 48

Diuretics used to tx hypercalcemia

Answer 48

Loop diuretics (loops lose calcium)

Question 49

S/E of loop diuretics

Answer 49

Ototoxicity -> tinnitus, hypokalemia, hyperuricemia, hypomagnesemia, hypotension

Question 50

Treat calcium stone formation

Answer 50

Thiazide diuretics (decrease Ca excretion)

Question 51

S/e of thiazide diuretics

Answer 51

Hypokalemia, hyponatremia, hypercalcemia, hyperuricemia

Question 52

Used to prevent mountain sickness (met acidosis with normal gap)

Answer 52

Carbonic anhydrase inhibitor (acetazolamide)