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Burt's Renal Final > Mechanisms to Adjust Urine Conc > Flashcards

Mechanisms to Adjust Urine Conc Flashcards

1
Q

TF:U = 1

A

The concentration of the substance in the tubule is the same as the plasma

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2
Q

The TF:U greater than 1

A

Substance is reabsorbed to a lesser extent than water

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3
Q

TF:U less than 1

A

Substance is reabsorbed more avidly than water

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4
Q

The loop of henle descending limb thin segment is permeable to? But impermeable to what

A

Water; NaCl which becomes more concentrated during descent

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5
Q

The primary cilia does what

A

Senses changes in osmolarity

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6
Q

The loop of henle ascending limb is permeable to what? Impermeable to what

A

NaCl (serves to dilute gradient); water

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7
Q

What is the main transporter in the thick ascending limb that we care about

A

NKCC and NaH antiporter

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8
Q

What ion drives luminal electrical voltage

A

K

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9
Q

What diuretics act on the thick ascending loops

A

Loop diuretics

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10
Q

When the luminal positive potential is reduced absorption of what is affected

A

Mg, Ca

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11
Q

The early segment of the distal tubule is permeable to what? Impermeable?

A

Na, Cl, Ca; water

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12
Q

The late segment of the distal tubule contains what cell types

A

Principal and intercalated

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13
Q

What do principal cells do

A

Na and water reabsorption; K secretion

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14
Q

What do intercalated cells do

A

Acid/base balance

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15
Q

What diuretics act on the early distal tubule and what transporter do they act on

A

Thiazide diuretics; NCC transporter

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16
Q

What diuretics act on the late segment DT principal cells?

A

Aldosterone antagonists and ENaC

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17
Q

What is more specific and binds tighter than spironolactone

A

Eplerenone

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18
Q

What diffuses down its gradients in the late segment DT of principle cells

A

Na, K, Cl

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19
Q

α intercalated cells function to change pH by doing what

A

Secrete H and resorb HCO3 during acidosis

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20
Q

Late segment DT β intercalated cells function in what

A

Alkalosis

Bicarb is secreted; H reabsorbed

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21
Q

What does water and chloride normally follow in the nephron

A

Na

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22
Q

Where is Cl active reabsorption

A

NaCl co-transporter (distal tubule)

Na-K-2Cl co-transporter (TAL)

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23
Q

What inhibits NaCl co-transporter

A

Thiazide in the distal tubule

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24
Q

What inhibits the NKCC co-transporter

A

Loop diuretics in the thick ascending loop

25
Q

Na reabsorption causes what

A

Water reabsorption and increased lumen negative potential, increased luminal Cl concentration, increased luminal urea concentration

Which causes passive Cl and urea reabsorption

26
Q

What 3 spaces are regulated independently to concentrate urine

A

Tubular space, vascular space, interstitial space

27
Q

What two things function to concentrate the urine

A

Counter current multiplier and exchanger

28
Q

What is the single effect

A

NaCl leaves the ascending loop where water is impermeable

29
Q

What is fluid flow

A

Descending limb and collecting duct leak water to try and dilute the interstitium

30
Q

What determines the size of the gradient in the nephron

A

Length of the loop of henle

31
Q

The passive reuptake of water from interstitium is called

A

Countercurrent exchange

32
Q

What are the transporters of urea in the medullary CD

A

UT-A1 and UT-A3

33
Q

What are the urea transporters in the thin limb

A

UT-A2

34
Q

What are the urea transporters activated by

A

ADH

35
Q

If you eat high protein what is the urea conc in the medulla? Low protein?

A

High urea, low

36
Q

What is the location in which urea is reabsorbed mostly

A

thick ascending limb

37
Q

What 2 things lead to the salty medulla

A

NaCl and urea

38
Q

How do we calculate obligatory urine volume

A

Minimum solute exretion per day / max urine concentrating ability

39
Q

Antidiuresis requires high ____ and high ______ of the renal medullary intersitial fluid

A

ADH; osmolality

40
Q

What is the contribution of urea and NaCl the hyperosmolality of the medulla

A

50/50

41
Q

High levels of ADH leaves to high levels of permeability of what

A

Water at the collecting duct and NA in the thick ascending limb

42
Q

An increase/decrease in blood flow dissipates the medullary gradient

A

Increase

43
Q

Reduced O2 causes what in the medullary interstitium

A

Reduced medullary gradient

44
Q

What 2 things cause a decrease in the medullary gradient

A

Decreased blood (O2 reduction) and increased vasa recta flow

45
Q

Where does ADH start changing the Osm

A

Medullary collecting duct on

46
Q

How do you calculate osmolar clearance

A

U_osm * V / P_osm

47
Q

How do you calculate free water clearance

A

C_h2o = V - C_osm

48
Q

When C_h2o is negative? Positive?

A

Excess solute removed and water is conserved; water is being excreted forming dilute urine

49
Q

How do you calculate fractional excretion

A

Clearance_x / GFR

50
Q

What does it mean when fractional excretion is greater than 1? Less than?

A

Secreted; reabsorbed

51
Q

What if the fractional excretion of Na is below 1%? Above 2?

A

Pre-renal; intra or post renal

52
Q

What does SIADH result in

A

Euvolemic hyponatremia

53
Q

What causes SIADH to give you euvolemic hyponatremia

A

ADH is secreted when it isn’t supposed to —> compensatory mechanisms —> volume and Na excreted

54
Q

What are the possible causes euvolemic hyponatremia

A

SIADH, COPD, malignancy

55
Q

What are some common causes of hypervolemic hyponatremia

A

CHF, renal impairment, cirrhosis

56
Q

What is central diabetes insipidus

A

Deficient secretion of ADH from hypothalamus or pituitary

57
Q

What is nephrogenic diabetes insipidus

A

Lack of renal response to ADH

58
Q

What are the symptoms of diabetes insidpidous

A

Polyuria, polydipsia, polyphagia

59
Q

How do you differentiate diabetes insipidus cases

A

ADH challenge test

Inject ADH and see if the body responds appropriately

Burt's Renal Final (7 decks)

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