05.08 - Reg of Body Fluid Osmolarity (Rao) - PP + Handout, No reading Flashcards Preview

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Flashcards in 05.08 - Reg of Body Fluid Osmolarity (Rao) - PP + Handout, No reading Deck (64):
1

4 Causes of Loss of Medullary Hyperosmolarity

(1) Diuretics; (2) Excessive delivery of fluid into LOH; (3) Decreased urea production; (4) Age, renal failure

2

Ability of kidneys to dilute or concentrate urine depends on

Difference between osmolar clearance and clearance of water

3

Activation of V2 in CD results in

insertion of Aquaporins into luminal membrane

4

Actual fluid flow - Cosm =

Free water clearance

5

ADH receptor in Epithelial cells of CD

V2

6

ADH responds to both

Posm, ECFV

7

At what plasma osmolarity does AVP reach max

295 mOsm

8

At what plasma osmolarity is AVP detectable

270-285 mOsm

9

AVP increase requires what threshold of ECFV loss

10-15% decrease in ECFV

10

Cause of Osmotic Diuresis

Hyperosmotic Plasma

11

Central Diabetes Insipidus results from

Pituitary gland doesn't release AVP

12

Common symptom of decreased ability to concentrate urine

Nocturia

13

Complications of Polydipsia

Hyponatremia, Coma, Death

14

Cwater =

UF x (1 - Uosm/Posm)

15

Dec PV after GI loss causes ___, but decreased plasma osmolarity causes ____

Inc AVP, Dec AVP

16

Difference between osmolar clearance and water clearance is

Free Water Clearance

17

How does ADH affect Posm, Uosm in Osmotic Diuresis

Remains: High, High

18

How does ADH affect Posm, Uosm in Primary Polydipsia

Low to Normal, Low to High

19

How does CD help with Medullary Hyperosmolarity

Active transport of Na into ISF

20

How does GI fluid loss lead to hyponatremia

(1) AVP release in response to volume; (2) Dilution of plasma; (3) Inc ECF volume; (4) Reduced osmolarity, Hyponatremia

21

How does heart failure cause hyponatremia

Loss of pressure stimulates hypovolemic hormone release

22

How does IMCD help with Medullary Hyperosmolarity

Passive diffusion of urea into ISF

23

How does liver failure cause hyponatremia

Loss of PV stimulates hypovolemic hormone release

24

How does Thick AL help with Medullary Hyperosmolarity

Active NaCl transport, Co-transport of K and Cl into ISF

25

How does Water Deprivation affect Posm, Uosm, and ADH in Nephrogenic DI

Increase, No change, Increase

26

How does WD affect Posm, Uosm, and ADH in Osmotic Diuresis

Inc, Inc, Inc

27

How does WD affect Posm, Uosm, and ADH in Primary DI

Increase, Remain low, No change

28

How does WD affect Posm, Uosm, and ADH in Primary Polydipsia

Normalize, Normalize, Increase

29

If free water clearance is negative, it means

Urine is being concentrated and BW is retained

30

If Uosm is greater than Posm

Negative Cwater -> Concetrated Urine -> Dec Posm

31

If Uosm is less than Posm

Positive Cwater -> Dilute urine -> Inc Posm

32

In condition of sever ECFV loss, it doesn’t matter what ___, ___ will rise

Doesn’t matter what serum osmolarity is, AVP levels will rise

33

Manifestations of Hyponatremia

Lethargy, Hyporeflexia, Mental confusion

34

Mutations that can cause Nephrogenic Diabetes Insipidus

V2 receptor, Aquaporin-2 --> CD doesn't respond to AVP

35

Na imbalance with GI fluid loss

Hyponatremia

36

Normal Cosm

2 +- 0.5 mL/min

37

Obligatory Urine volume

.5 L / day

38

Osmolar Clearance =

(UF x Uosm) / Posm

39

Osmolar clearance is elevated under condition of

Plasma Hyperosmolarity

40

Osmolar clearance measures

kidney's ability to concentration urine

41

Calculated Plasma Osmolarity =

2 x Na + (glu/18) + (bun/2.8)

42

Positive free water clearance indicates

Dilution of urine and concentration of plasma

43

Resting Posm, Uosm, and ADH in Osmotic Diuresis

High, High, Normal

44

Substantial dec in ECFV stimulates ADH release even

under condition of hypo-osmolar plasma

45

T/F: ADH increases linearly with decreased ECFV

False, logarithmic - Very slow increase at first until threshold met

46

Thick Ascending Limb is permeable to

Active NaCl transport, (K, Cl)

47

Thin Ascending Limb is permeable to

Passive NaCl, some urea

48

Thin Descending Limb is permeable to

H20, some urea

49

To assess efficacy of kidney to concentrate or dilute urine, must first

quantitate the rate of excretion of solute (using Osmolar Clearance)

50

Two other conditions besides GI Fluid Loss that lead to Hyponatremia with no change in ECFV

(1) Heart Failure - Loss of pressure stimulates hypovolemic hormones; (2) Liver failure - Reduce PV stimulates hypovolemic hormones

51

Two special features that contribute to preservation of medullary interstitial hyperosmolarity

(1) Meduallry BF is low; (2) Vasa recta serves as countercurrent exchanges

52

Tx of Hyponatremia due to GI Fluid Loss

Infusion of Isotonic Saline, avoid quick change

53

Under condition of severe volume loss, effect of ___ on ___ overides ___

Effect of ECFV loss on AVP overrides osmolarity effect

54

Urea contributes what % of osmolarity in Medullary ISF

40%

55

Water clearance is how much

water without any solute is cleared in urine

56

Water deprivation in DI must be stopped if

BW falls >5%, Posm > 300 mOsml/kg

57

What can override normal response to plasma osmolarity

Severe decrease in ECFV

58

What is dilemma with severe volume loss and low serum osmolarity

Low osmolarity inhibits ADH so as to correct; But severe volume loss overrides in order to maintain volume

59

What signals mediate V2 activity

AC -> cAMP -> PKA

60

Where are osmoreceptors in the brain that stimulate ADH release in response to increase osmolarity

Supraoptic and Paraventricular Nuclei of Hypothalamus

61

Where is AVP degraded

PT and Liver

62

Where is the thirst center in the brain?

Lateral Preoptic Nucleus of the Hypothalamus

63

Which is more efficient: Clearing water or conserving

Clearing fo sho

64

Which part of CD is permeable to Urea

Inner Medullary