Urine Concentration Physiology

  1. True/false: excess sodium alone leads to isotonic expansion of the ECF
    False; sodium alone would not be isotonic, it would lead to expansion of ECF by drawing water from ICF
  2. True/false: excess sodium and water leads to isotonic expansion of the ECF only
  3. What is the body osmolarity normally set at?
    290 mOsm/L
  4. What does isosmotic urine mean?
    Osmolarity of urine equals to blood osmolarity
  5. What is hyperosmotic urine in relation to blood osmolarity
    Higher concentration of solute
  6. What is hypoosmotic urine in relation to blood osmolarity
    Lesser concentration of solute
  7. How does the body respond to water deprivation?
    Osmoreceptors in the hypothalamus produces ADH for posterior pituitary releases ADH to principal cells in late distal tubule and collecting duct
  8. ADH ______ plasma osmolarity and _____ urine volume and _____ urine osmolarity
    • Decreases
    • Decreases
    • Increases
  9. High osmolarity is ______ in solute and ____ in water
    • High
    • Low
  10. Drinking water would ____ urine osmolarity
  11. Is the medullary interstitium hyper or hypo osmotic?
  12. True/false: overhydration can lead to washout of the medullary interstitium
  13. Water is pulled from the _____ loop of henle to equilibrate with the interstitium, while NaCl is pulled from the _____ loop to add to the interstitium gradient
    • Descending
    • Ascending
  14. True/false: NaCl absorption in the ascending limb increases the osmolality in the interstitial fluid
  15. Osmolality is higher ________
    Deeper into the medulla
  16. Where is urea filtered? Reabsorbed to the outer medulla? Secreted? Reabsorbed to the inner medulla?
    • Proximal tubule
    • Proximal tubule
    • Thin limbs of loop of henle (both thin descending and ascending)
    • Collecting ducts
  17. True/false: urea is reabsorbed in the proximal tubule
  18. True/false: urea is reabsorbed in the collecting ducts
    True, moving to the interstitial fluid to increase the osmotic gradient
  19. True/false: ADH stimulates a specific urea uniporter in the inner medullary collecting ducts to increase urea reabsorption
    True, this would draw more water out too
  20. True/false: the efferent arterioles from many of the juxtamedullary glomeruli extend down into the outer medulla
    true; forming parts to the vasa recta which helps move fluid in the interstitium back to the capillaries
  21. Vasa recta pulls solutes in as it is _____ and losing that solute as it _______
    • Descending
    • ascending
  22. Vasa recta flow is a ____ (high/low) flow
  23. True/false: sodium is reabsorbed from the thick ascending limb into the outer medulla and distributed to the inner medulla via descending vasa recta
  24. How is urine osmolarity regulated?
    Using ADH and medullary osmotic gradient
  25. Where is ADH produces and where are the neurons located
    Hypothalamic neurons located in the supraoptic and paraventricular nuclei
  26. Where is ADH released?
    Posterior pituitary
  27. How does ADH work?
    Through G-protein to insert aquaporin channels into the luminal membrane of the principal cells
  28. What happens to plasma osmolarity is ADH and thirst system is blocked?
    plasma osmolarity goes way up (aka high salt, low water)
  29. True/false: increased extracellular volume induces increased ADH
    False; decreased extracellular volume induces increased ADH
  30. True/false: Baroreceptors firing inhibits ADH release
  31. What happens to ADH when there is decreased cardiovascular pressure and less firing by the baroreceptors?
    The inhibition on ADH release is no longer there with baroreceptors not firing, so ADH release is increased
  32. ADH is also known as?
  33. True/false: ADH concentration can get so high that it has a direct effect on arterioles leading to an increased to total peripheral resistance and thus arterial blood pressure goes up
  34. True/false: Less ADH would lead to reduced pressure on the baroreceptors
    True; since less ADH means that less water getting reabsorbed so blood pressure would lower
  35. Paraventricular nuclei is more important for ______, while supraoptic nuclei are more important for _____.
    • ADH release
    • Osmoregulation
  36. True/false: Angiotensin II is also a potent thirst stimulator
  37. At which concentration does ADH start to circulate in the blood?
    280 mOSm/kg (normal is 290 mOSm/kg)
  38. True/false: body is more sensitive to volume changes than it is to osmotic changes
    False; body is more sensitive to osmotic changes, and would affect plasma ADH more
  39. Which is more sensitive osmoreceptors or baroreceptors?
    • Osmoreceptors
    • Unless it is a large pressure change, then baroreceptors take precedence
  40. True/false: pregnant women can have vasopressinase in their system produced by the placenta, and thereby breaking down ADH
  41. What would be an example nephrogenic deficit that would result in faulty ADH functioning?
    Lithium prevents the insertion of aquaporin channels in the collecting duct by limiting cAMP production
  42. What is pressure natriuresis?
    Increases in renal artery pressure leading to loss of sodium and water
  43. Na+/K+/2Cl- symporter is found in which segment?
    Thick ascending loop of henle
  44. Concentrated urine would have ______ solutes in the interstitial fluid composition.
    High; as in more solutes so drawing more water out of the ducts, therefore resulting in concentrated urine
  45. Maximum diuresis is ___ (maximum/no) ADH.
  46. Maximum antidiuresis is ____ (maximum/no) ADH.
  47. What is the most effective player in long-term control of sodium balance?
  48. True/false: aldosterone affects sodium transport in sweat and salivary ducts and the intestine
  49. Where is aldosterone produced?
    Adrenal glands (zona glomerulosa)
  50. True/false: aldosterone is produced in the hypothalamus
    False; aldosterone is produced in the adrenal gland, ADH is produced in the hypothalamus
  51. What stimulates the release of aldosterone?
    Angiotensin II and plasma potassium levels
  52. True/false: ADH stimulates the release of aldosterone
    False; angiotensin II does, it is part of the RAAS system
  53. Aldosterone has to do with ____ plasma level, and ADH has to do with _____ plasma level
    • Na+
    • Water
  54. True/false: decrease in NaCl at the macula densa leads to increase renin release from the granular cells
  55. Which type of nerve stimulates renin secretion from granular cells?
    Renal sympathetic nerve
  56. True/false: renal sympathetic nerve activity constrict the afferent arteriole to increase GFR and renal blood flow
    False; it decreases GFR and RBF
  57. Angiotensin II leads to _________
  58. How does angiotensin II affect renal sodium reabsorption?
    Increases renal sodium reabsorption to expand ECF volume
  59. Where in the tubule does angiotensin II act on?
    Proximal tubule to affect Na-H exchange
  60. Where in the tubule does aldosterone act on?
    Collecting tubule
  61. Angiotensin II mostly constrict ____ arteriole, but also to a lesser degree ___ arteriole as well.
    • Efferent
    • Afferent
  62. True/false: aldosterone is a steroid hormone
  63. What inhibits aldosterone secretion?
    Atrial natriuretic peptide inhibits aldosterone secretion by inhibiting renin release
  64. True/false: ANP inhibits renin and angiotensin II release thereby inhibiting aldosterone secretion
  65. True/false: ADH is involved in the RAAS
    False; it is Renin-> angiotensin II -> aldosterone
  66. Angiotensinogen is from the ______ , and converted to angiotensin II in _______.
    • Liver
    • Lungs
  67. True/false: atrial natriuretic peptide is made in the kidneys
    False; it is made in the heart by distension of the atria
  68. Atrial natriuretic peptide has what effect on afferent arteriole? Efferent arteriole?
    • Relaxes afferent arteriole and increases filtration
    • Constricts efferent arterioles
  69. ANP has what effect on GFR?
  70. ANP is secreted in response to what?
    increased sodium intake
  71. What is ANP’s effect on sodium reabsorption in the collecting duct?
    Inhibits it
  72. True/false: ANP is more effective at plasma volume control than ADH
    False; ANP is less effective than ADH for plasma volume control
  73. Which hormones indirectly increase sodium reabsorption?
    Cortisol, estrogen, growth hormone, thyroid hormone, insulin
  74. Which hormones indirectly decrease sodium reabsorption?
    Glucagon progesterone, PTH
  75. How is free water clearance calculated?
    • C(H2O) = V-C(osm)
    • V=urine flow rate
    • C(osm)= osmolar clearance = (UxV)/P
  76. True/false: if you’re dehydrated, you want to have your free water clearance to be high
    False; free water clearance should be low in dehydrated state so to retain water
  77. True/false: loop diuretic inhibits NaCl reabsorption in thick ascending limb
  78. When C(H2O) is >0, it means solute-free water is _______. When C(H2O) is < 0, it means solute-free water is _____.
    • Excreted
    • Absorbed
  79. True/false: If water clearance in dehydrated state is between -15 to +15, it means that there is imminent renal failure
  80. What is the normal water clearance rate in dehydrated state?
    -25 to -20 mL/hr as kidneys want to retain water instead of clearing them
  81. What is nephrogenic diabetes insipidus?
    Kidneys not responding to ADH
  82. What is central diabetes insipidus?
    Pituitary ADH is low
  83. True/false: high water intake and low ADH would lead to a positive water clearance value
  84. True/false: low water intake and high ADH would lead to a negative water clearance value
  85. What happens to extracellular volume when there is increased sodium intake?
    More water is brought in so ECF volume go up
  86. What is EABV?
    Effective arterial blood volume
  87. What happens to EABV when there is an increased Na+ intake?
    goes up
  88. Increase Na+ intake, the body would want to ______ sodium reabsorption and ______ excretion
    • Decrease
    • Increase
  89. Increased Na+ intake would _____ ANP
  90. Decreased Na+ intake would ____ RAAS activity
    Increase, thereby increase sodium reabsorption
  91. Which diuretic has action on proximal tubules?
    Osmotic diuretics
  92. Which diuretic has action on the thick ascending loop?
    Loop diuretics
  93. Which diuretic has action on early distal tubules?
    Thiazide diuretics
  94. Which diuretics have affect chloride transport?
    Loop diuretics and thiazide
  95. What is the mechanism of action for osmotic diuretics?
    Inhibit water and Na+ reabsorption by increasing osmolarity of tubular fluid
  96. What is the mechanism of action for loop diuretics?
    Inhibit Na+- K-Cl- co transport
  97. Which mechanism of action of thiazide?
    Inhibit Na+-Cl- cotransporter
  98. Where does carbonic anhydrase act on?
    Proximal tubule
  99. True/false: carbonic anhydrase has mild diuretic effect
  100. True/false: loop diuretics and thiazide are load dependent
  101. True/false: loop diuretic result in reduced reabsorption of Ca2+ and Mg2+
  102. True/false: thiazide increases Ca2+ reabsorption by stimulating Ca2+/Na+ exchange
  103. What condition could result with thiazide diuretics use?
  104. K+ sparing diuretics have affect on which cells?
    Principal cells of the collecting duct
  105. What is the effect of K+ sparing diuretics?
    Blocks Na+ channel so reduce Na+ reabsorption and reduce K+ secretion
  106. K+ Sparking diuretics can be used to treat which disease?
    Liddle syndrome
  107. What is overfill pitting edema?
    Too much EABV
  108. What is underfill pitting edema?
    • Too little EABV
    • Veins holding onto fluid and thus fluid leak out
  109. True/false: non-pitting edema is evenly distributed over areas of low tissue pressure
  110. What condition is an example of reduced EABV?
    Congestive heart failure
  111. True/false: underfill edema result in low blood pressure and thus would have increased release of renin and ADH
  112. What is the starling equation?
    Fluid movement (J) = Kf(constant) [(cap hydrostatic pres – interstitial hydrostatic press) – (cap oncotic pres – interstitial oncotic pres)]
  113. What are causes of edema:
    • Increased cap filtration pressure
    • Decrease cap osmotic pressure
    • Increase cap permeability
    • Obstruction of lymph flow
Card Set
Urine Concentration Physiology
Renal Midterm- Physiology