Urinary- GFR and RBF

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Mawad
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307031
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Urinary- GFR and RBF
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2015-09-02 22:24:58
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vetmed urinary
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vetmed urinary
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  1. The virtual volume of plasma from which a given substance is removed by the kidneys in one minute.
    clearance
  2. Clearance is a ________.
    rate
  3. What is the equation for renal clearance?
    Px Cx = Ux V

    • Px=plasma conc of substance X (mg/mL)
    • Cx=clearance of substance X (mL/min)
    • Ux=urine conc of substance X (mg/mL)
    • V=urine flow rate (mL/min)
  4. Most of the renal blood flow goes to the ________.
    cortex
  5. Blood flow to the ________ is similar to that of resting muscle.
    medulla
  6. Describe the pattern of flow through the nephron.
    afferent arteriole--> glomerular capillaries--> efferent arteriole--> peritubular capillaries--> ultrafiltrate in Bowman's space
  7. What are solutes are filtered from the ________ into _______, then pass through the _______.
    capillary spaces; Bowman's space; tubules
  8. What are the 3 structures that are the primary controls of the ultrafiltrate composition?
    capillary endothelium, glomerular basement membrane, visceral epithelium/podocytes
  9. The capillary endothelium is _______, so that ________ are excluded from the ultrafiltrate, but _______ are not.
    fenestrated; blood cells; large macromolecules
  10. The luminal surface of the capillary endothelium is covered by __________, which contribute to the _________.
    negatively-charged sialoglycoproteins; charge selectivity
  11. The capillary endothelium filtered based on...
    charge selectivity
  12. What is the innermost barrier of the glomerular filtration barrier?
    capillary endothelium
  13. What are the components of the glomerular basement membrane?
    lamina rara interna, lamina densa, lamina rara externa
  14. The lamina rara interna and the lamina rara externa contain ____________, which contribute to __________.
    negative polar noncollagenous proteins; charge selectivity
  15. The lamina densa contains _________, which contribute to ________.
    nonpolar collagenous proteins; size selectivity
  16. The glomerular basement membrane filters based on...
    charge selectivity, size selectivity
  17. What is the outermost layer of the glomerular filtration barrier?
    visceral epithelium (aka podocytes)
  18. Describe the morphology and construction of the podocytes on the visceral surface of the glomerular basement membrane.
    interdigitating secondary foot processes that form filtration slits
  19. A complex of proteins, such as ________, on the interdigitating foot processes form a _________, which contributes to __________.
    nephrin; slit diaphragm; size and shape selectivity
  20. Podocytes are __________, enabling them to...
    phagocytic; engulf macromolecules trapped by the slit diaphragm.
  21. Podocytes have a __________ coat, which contributes to ___________.
    negatively-charged sialoglycoprotein; charge selectivity
  22. Podocytes filter based on...
    size and shape selectivity, charge selectivity
  23. The ___________ synthesized part of the glomerular basement membrane.
    visceral epithelium
  24. What is the purpose of the mesangium?
    stabilizing core and anchor for the glomerulus
  25. Describe how the mesangium is part of the juxtaglomerular apparatus.
    extraglomerular mesangium fills the space b/w the macula densa and the glomerular arterioles
  26. Mesangial cells are smooth muscle and therefore can...
    alter the amount of surface area available for filtration.
  27. Mesangial cells are _______ and cant therefore clear residues of filtration from the mesangial space.
    phagocytic
  28. Particles are restricted on the basis of size primarily by the __________; but _________ also contribute to size selectivity.
    lamina densa; podocytes
  29. Particles are restricted on the basis of charge by...
    negatively-charged sialoglycoproteins and peptidoglycan of the endothelium, lamina rara interna, lamina rara externa, and podocytes.
  30. Negatively-charged macromolecules experience __________ restriction to filtration than do neutral and positively-charged ones.
    greater
  31. Rigid molecules are _______ likely to pass through the _________ than flexible ones.
    less; podocyte slit diaphragm
  32. What are the Starling forces?
    hydrostatic pressure, oncotic pressure
  33. The total filtration rate of both kidneys.
    GFR
  34. Juxtamedullary nephrons have ________ loops of Henle that penetrate the ________; they tend to...
    long; inner medulla; conserve solute and water.
  35. Superficial cortical nephrons have ________ loops of Henle that penetrate the _________; they tend to...
    short; outer medulla; excrete more water and solute.
  36. Hydrostatic pressure drives fluid into _________.
    Bowman's space
  37. Oncotic pressure keeps fluid __________.
    within the capillary bed
  38. Oncotic pressure is driven by __________.
    proteins within the glomerular capillary
  39. SNGFR=
    Kf [(Pgc- Pbs)- (Pigc)]

    • Pgc= hydrostatic pressure of glomerular capillary
    • Pbs= hydrostatic pressure of Bowman's space
    • Pigc= oncotic pressure of glomerular capillary
  40. The oncotic pressure of the glomerular capillary increases along the length  of the capillary due to...
    the loss of protein-free ultrafiltrate into Bowman's space, thus increasing the concentrations of proteins in the remaining plasma.
  41. Describe filtration equilibrium.
    By the efferent end of the glomerular capillary, the rise in oncotic pressure in the glomerular capillary due to hemoconcentration balances out the hydrostatic pressure difference and filtration stops
  42. The ultrafiltration coefficient (Kf) depends on... (2)
    the surface area available for filtration and the permeability per unit area of the capillary.
  43. Kf can change in response to _________ that cause the mesangium to ________, thus ________ the surface area available for filtration.
    vasoactive; contract; decrease
  44. Factors that DIRECTLY affect GFR.
    oncotic pressure, hydrostatic pressure, surface area, permeability
  45. Factors that INDIRECTLY affect GFR.
    plasma flow, mean arterial pressure, resistance in afferent and efferent arterioles
  46. What effect does dehydration (hemoconcentration) have on GFR?
    hemoconcentration--> increase in plasma protein--> increase in oncotic pressure in capillary bed--> decrease in GFR
  47. What effect does hypoproteinemia have on GFR?
    hypoproteinemia--> decrease in plasma protein--> decrease in oncotic pressure in capillary bed--> increase in GFR
  48. What effect does urinary tract obstruction have on GFR?
    obstruction of outflow--> increase in hydrostatic pressure in Bowman's space--> decrease in GFR
  49. What effect does nephrotic syndrome (proteinuria) have on GFR?
    proteinuria--> protein enters Bowman's space--> increase in oncotic pressure in Bowman's space--> increase in GFR
  50. When there is low flow through the glomerulus, oncotic pressure in the capillary bed ________ more rapidly, ________ is reached sooner, and GFR ________.
    increases; filtration equilibrium; ceases prior to the end of the glomerular capillary bed
  51. What are the major sites of resistance in the kidney?
    afferent and efferent arterioles
  52. Changes in resistance in the afferent arterioles result in ________ changes in GFR and RBF.
    parallel
  53. Changes in resistance in the efferent arterioles result in ________ changes in GFR and RBF.
    opposite
  54. Contraction of mesangial cells -->
    decrease in SA--> decrease in Kf--> decrease in SNGFR
  55. Vasorelaxants affecting mesangial cells-->
    increase in SA--> increase in Kf--> increase in SNGFR
  56. How does decreased resistance in afferent arteriole affect RBF and GFR?
    increase in RBF and GFR
  57. How does increased resistance in the afferent arteriole affect RBF and GFR?
    decrease in RBF and GFR
  58. How does decreased resistance in the efferent arteriole affect RBF and GFR?
    increase RBF, decreased GFR
  59. How does increased resistance in the efferent arteriole affect RBF and GFR?
    decreased RBF, increased GFR
  60. What vasoactive substances can cause constriction of glomerular arterioles? (5)
    norepinephrine, angiotensin II, endothelin, vasopressin, throboxane
  61. With moderate sympathetic activation, the _______ arteriole constricts more then the _______ arteriole; thus, _____ falls more than ______.
    efferent; afferent; RBF; GFR
  62. With _____________, the afferent and efferent arterioles constrict the same, and both GFR and RBF fall.
    high sympathetic activation
  63. With vasoconstriction, there is a ________ in Kf; it also stimulates granular cells to release ______ and activate the _________.
    decrease; renin; renin-angiotensin system
  64. Describe the renin-angiotensin system.
    vasoconstriction--> renin released from granular cells--> renin converts angiotensinogen to angiotensin I--> ACE converts angiotensin I to angiotensin II--> Ang II induces release of endothelins--> efferent arterioles constrict and RBF falls
  65. With the RAS, the _______ arteriole constricts more then the ________ arteriole; ______ falls, while ________ remains constant.
    efferent; afferent; RBF; GFR
  66. Angiotensin II induces the release of _________, which are potent vasoconstrictors
    endothelins
  67. Endothelins constrict __________ to decrease the ______; it also decreases ________ by _________.
    afferent and efferent arterioles; GFR; Kf; mesangial contraction
  68. Atrial Natriuretic Peptide __________ the afferent arteriole, _________ the efferent arteriole, causing ______ and ______ to increase and inhibits ________ release.
    vasodilates; +/- vasoconstricts; GFR; Kf; renin
  69. Prostaglandins, dopamine, and nitric oxide are _________.
    vasodilatory
  70. What is the equation for filtration fraction?
    FF= GFR/RPF
  71. Fraction of plasma that becomes ultrafiltrate; determines the water and solute load to tubules.
    filtration fraction
  72. Intrinsic ability of an organ to maintain blood flow at a nearly constant rate despite changes in arterial perfusion pressure.
    autoregulation
  73. What is the equation for flow Q?
    Q=P/R

    • P=pressure
    • R= resistance
  74. If flow Q is to remain constant as pressure P changes, ...
    resistance R must change proportionately to P
  75. Autoregulation of the kidney is mediated by the _________.
    afferent artiole
  76. What are the mechanisms of autoregulation of glomerular flow?
    myogenic control, tubuloglomerular feedback
  77. As perfusion pressure increases and stretches the afferent arteriole, it _________ and limits transmission of this increased pressure to the _________.
    constricts; glomerulus
  78. Describe tubuloglomerular feedback.
    juxtaglomerular apparatus- increase in glomerular pressure--> increased colloid pressure in distal tubule--> macula dense senses [Cl-] [K+] [Na+]--> MD releases adenosine--> vasoconstriction to decrease flow-->decrease in SNGFR
  79. Volume expansion shifts the TGF curve to the _________ to _______ water and sodium; this is because volume expansion causes _______ sensitivity to tubuloglomerular feedback.
    right; waste; decreased
  80. Dehydration/blood loss (volume contraction) shifts the TGF curve to the _________ to ________ water and sodium; this is because volume contraction causes _________ sensitivity to tubuloglomerular feedback.
    left; conserve; increased
  81. A high protein diet increases __(2)__ resorption by the __________, which registers as decreased flow by the macula densa, decreasing the TGF signal and allowing higher ____________; RBF and GFR ________, which can contribute to renal damage.
    Na and Cl; Loop of Henle; glomerular pressure and flow; increase
  82. Ideally a solute used to measure GFR has the following characteristics. (4)
    freely filtered at glomerulus, not secreted/resorbed by tubules, not metabolized by the kidney other organ, not excreted by another organ
  83. What is the equation for measurement of GFR?
    GFR=UxV/Px

    • Ux=conc of solute in urine
    • V=volume
    • Px=conc of solute in plasma
  84. If solute X is neither resorbed or secreted, clearance of X ____ GFR.
    =
  85. If solute X is reabsorbed, clearance of X _______ GFR.
    <
  86. If solute X is secreted, clearance of X _____ GFR.
    >
  87. Clearance of x/ clearance of inulin= net handling of x

    if ratio > 1, then net __________
    if ratio < 1, then net __________
    secretion; reabsorption
  88. Ideally a solute used to measure RPF has the following characteristics. (4)
    freely filtered at glomerulus, completely excreted by the tubules, not metabolized by the kidney or another organ, not excreted by another organ
  89. When determining  renal plasma flow, assume _______ and _______ are the same.
    renal arterial; venous plasma flow
  90. What substance is used to determine GFR?
    inulin, creatinine
  91. What substance is used to determine RPF?
    PAH
  92. Renal disease implies the presence of __________.
    histologic lesions
  93. Renal failure implies __________ but not __________.
    75% of nephrons are non-functional; histologic lesions
  94. Pre-renal azotemia is due to...
    decreased renal perfusion- dehydration, shock
  95. Primary renal azotemia is due to...
    renal parenchymal disease
  96. Post-renal azotemia is due to...
    impaired elimination of urine from the body- obstruction, ruptured bladder
  97. Clinical and biochemical abnormalities associated with a critical loss of functioning nephrons.
    uremia
  98. Urea is an end product of ____________; it is synthesized in the _________.
    protein and AA catabolism; liver
  99. Urea is ________ across _________; it is distributed throughout TBW.
    freely permeabile; cell membranes
  100. Urea is filtered in the ________; it is _________ from the renal tubules.
    glomeruli; passively resorbed
  101. _______ urea is passively resorbed with more rapid tubular flow rates, and vice versa.
    Less
  102. Urea is not ________ by the renal tubules.
    secreted
  103. __________ can increase GFR and urea excretion.
    High-protein meals
  104. Non-renal factors for increased BUN. (4)
    high protein meal, hemorrhage in the GI, increased catabolism, drugs
  105. Renal factors of increased BUN.
    pre-renal (dehydration, shock), renal (parenchymal dz), post-renal (obstruction, rupture)
  106. Non-renal factors for decreased BUN. (4)
    low protein diet, severe liver disease, portosystemic shunt, anabolic steroids
  107. Creatinine is a breakdown product of ____________.
    phosphocreatinine in muscle
  108. Creatinine is released into the blood at a _________ rate for __________.
    constant; a given individual (compare to Hx, not normal values range if possible)
  109. Creatinine for a given individual can depend on... (3)
    age (young have lower), sex (males have higher), muscle mass (skinny have lower)
  110. Creatinine is excreted by the kidneys almost entirely by ____________.
    glomerular filtration
  111. Creatinine is __________ from the renal tubules.
    neither reabsorbed nor secreted
  112. _________ may constitute up to 50% of the measured creatinine at normal serum creatinine concs; as creatinine goes up due to pathology, it is less significant.
    Non-creatinine chromagens
  113. Renal factors for increased creatinine.
    pre-renal, renal, post-renal
  114. Factors for decreased creatinine. (3)
    severe loss of muscle mass, small body size, young age
  115. What is SDMA?
    increases in serum earlier than creatinine; not affected by muscle mass
  116. The slope of the hyperbola (serum cre/BUN vs GFR) is _______ when GFR is mildly or moderately decreased.
    small
  117. The slope of the hyperbola (serum cre/BUN vs GFR) is ________ when GFR is severely reduced.
    large
  118. When non-renal variable have been eliminated from consideration, an increase in BUN/Cre conc about normal implies...
    at least 75% of the nephrons are not functioning
  119. Pre-renal azotemia tends to be _______.
    mild
  120. Post-renal azotemia tends to be _______.
    severe
  121. Compare endogenous creatinine clearance when compared to exogenous.
    endogenous requires 24hr of urine collection (difficult), endogenous underestimates GFR because of non-cre chromagens, exogenous eliminates error due to chromagens, exogenous more closely approximates inulin clearance
  122. The main indication for determination of creatinine clearance is...
    PU/PD and no azotemia, leading to suspicion of renal disease
  123. What is Iohexol?
    contrast agent that allows estimate of GFR with limited number of plasma collections and no need for urine collection

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