Human Physiology

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hillab@warhawks.ulm.edu
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15262
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Human Physiology
Updated:
2010-04-20 21:43:16
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biology kidney physiology
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test 3
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  1. what are the fuxns of the kidneys
    • make urine
    • regulate osmotic pressure of plasma and other extracellular fluids
    • regulate the excretion of sodium and water
    • regulate the individual concentration of numerous electrolytes
    • regulate plasma bicarbonate concentration
    • eliminate metabolic waste products
    • produce hormones, proteolytic enzymes, paracrines, active D, and glucose
  2. what is the outer part of the kidney
    cortex
  3. what is the inner part of the kidney
    medulla
  4. what is the basic unit of kidney structure and fuxn.
    nephron
    • A - Proximal Convoluted Tubule
    • B - Loop of Henle
    • C - Distal Convoluted Tubule
    • D - Collecting Duct
  5. what are the two types of nephrons
    • cortical
    • juxtamedullary
  6. how do you id a cortical nephron
    loop of Henle is short
  7. how do you id a juxtamedullary nephron
    long loop of henle
  8. what is the ratio of cortical to juxtamedullary in humans
    • 85% cortical
    • 15% juxtamedullary
  9. what are the major structures of a proximal tubular cell
    • microvilli
    • brush border
    • tight junction
    • basolateral cell membrane
    • basement membrane
  10. what
  11. what is the flow of blood through the kidneys
    • artery
    • afferent arterioles
    • glomerulus
    • efferent arteriole
    • peritubular capillaries
    • vein
  12. what is the vasa recta
    capillaries that descend into and ascend from the medulla in parallel with the tubular structrures
  13. where is blood flow/pressure highest in the nephron and why
    glomerulus b/c filtration happens there
  14. where is blood pressure/flow lowest and why
    • peritubular capillaries for uptake of fluid reabsorbed by the tubules
    • maintain higher osmotic pressure
  15. what is the extrinsic mechanism in the kidney vessels
    innervation by SNS releases NE that binds to alpha receptors causing vasoconstriction of the afferent arterioles
  16. how are kidneys regulates without the sympathetic nerve fibers
    intrinsic mechanisms/renal auto regulation
  17. how does renal autoregulation fuxn
    • if BP/flow increases, the afferent arterioles constrict
    • if BP/flow decreases, the afferent arterioles dilate
  18. how does changes in BP/flow affect filtration and excretion
    changes in BP/flow = changes in filtration = big changes in excretion
  19. what can happen if BP/flow remains high
    permanent constriction of afferent arterioles leads to kidney failure
  20. what is the juxtaglomerular apparatus
    structure in the kidneys consisting of macula densa, extraglomerular mesangial cells, and granular cells, located in the region where the distal tubule touches afferent and efferent arterioles of its parent glomerulus
  21. what are granular cells
    cells embedded in the smooth muscle walls of afferent arterioles responsible for synthesizing and releasing renin
  22. where is renin released
    by the granular cells of the juxtaglomerular apparatus
  23. what is the fuxn of renin
    if BP/flow decreases to the kidneys then renin released end result is angiotensin II is formed that stims adrenal cortex to secrete aldosterone
  24. what is the fuxn of aldosterone
    stims Na reabsorption by the collecting ducts
  25. what are macula densa cells
    epithelial cells in the DCT
  26. what are extraglomerular mesangial cells
    messenger cells b/t the granular and macula densa cells
  27. what is the tubuloglomerular feedback
    NaCl composition of tubule fluid in DCT is relayed bact to afferent arterioles, changes in blood flow changes filtration
  28. what is the fuxn of the nephron
    form urine
  29. what are the steps of urine formation
    • glomerular filtration
    • tubular reabsorption
    • tubular secretion
  30. what is glomerular filtration
    • the first step in the formation of urine that is non-selective filtration of plasma
    • allows passage of anything w/ mw <10,000 out of blood into lumen of Bowman's capsule
  31. what is GFR
    the # of ozs. filtered out of blood at given amt. of time
  32. what is tubular reabsorption
    process whereby substances are transferred out of the tubular fluid and returned to the peritubular capillaries; much more selective
  33. where does the bulk of reabsorption occur
    PCT
  34. what is tubular secretion
    mvmt of substances across tubule epithelium in a direction opposite to reabsorption
  35. how much is excreted, filtered, and reabsorbed daily
    • excrete 1.5 -2L/day
    • filter 180 L/day
    • reabsorb 178L/day
  36. what is the fuxn of glomerular filtration
    always takes out of blood into lumen of tubule
  37. what is the glomerular filtration membrane
    three layers capillary endothelium, glomerular basement membrane, podocyte cell layer
  38. what is characteristic of the 1st layer of the glomerular filtration membrane
    fenestrae pores of about 50 -100 nm
  39. what is characteritic of the 2nd layer of the glomerular filtration membrane
    meshwork of fine fibrils embedded in a gel-like matrix
  40. how is the epithelium of the bowman's capsule
    has slit pores
  41. what does all three layers of the glomerular filtration membrane contain and what do they do
    contain glycoproteins that are negatively charged, which repel negative charged plasma proteins
  42. why is the measurement of GFR important
    valuable indication of renal fuxn
  43. what is necessary to measure GFR
    a cmpd that is not secreted or reabsorbed, allows the amt filtered to = amt excreted
  44. what cmpd is meets the requirements for GFR measurement
    inulin
  45. what is inulin
    cmpd form onion/artichoke
  46. what is the formula for clearance
    C = (U * V)/ P
  47. what is renal plasma clearance
    the rate of excretion of a substance divided by its plasma concentration
  48. what are the symbols in C=(U*V)/P
    • u - urine concentration
    • p - plasma concentration
    • v - urine flow rate
  49. what is the urine flow rate
    2ml/ min
  50. what is the clearance rate of inulin
    120ml/min
  51. what are the types of reabsorption
    • active
    • passive
  52. how much water do we excrete a day
    2L/day
  53. what is obligatory water loss
    the amt of we need to excrete a day which is 400ml/day
  54. what is actively reabsorbed
    • glucose
    • Na
    • uric acid
    • phosphate
  55. how is glucose reabsorbed
    • in PCT
    • coupled transport tw/ Na out of lumen
    • into PCT cell out basolateral membrane by facilitated diffusion
  56. how is Na reabsorbed
    • in PCT
    • coupled to glucose, some amino acids, phosphate, Cl, and water
  57. how is uric acid reabsorbed
    in PCT
  58. what causes gout
    high plasma levels of uric acid
  59. what is a symptom of gout
    big toe pain b/c crystal build up in the vessels of that region
  60. what is given to gout patients
    uricosuric agent to lower uric acid levels in plasma by blocking reabsorption of uric acid
  61. what is a uricosuric agent
    Probenecid
  62. what is passively reabsorbed
    • water
    • Cl
    • urea
  63. what is tubular secretion
    out of peritubular capillaries into tubule fluid
  64. why is tubular secretion necessary
    supplements filtration process
  65. what can be secreted
    • organic ion
    • penecillin
  66. what blocks reabsorption and secretion
    probenecid
  67. what is given to patients with penicillin and why
    • probenecid
    • to help patients that don't come back for next shot
    • inhibits peniciliin secretion
  68. what is related to Na reabsorption
    H and K secretion by antiport transport
  69. how is H secreted
    in PCT
  70. what causes acidified urine
    H in urine
  71. where is potassium secreted
    early in collecting ducts
  72. how is potassium secreted
    assoc. w/ Na/K ATPase pump
  73. what cmpd is necessary to measure total renal plasma flow
    PAH
  74. what happens to PAH
    almost completely cleared from the blood in 1 pass thru
  75. what is the total renal plasma flow rate
    625 ml/min
  76. why is Na reabsorption in the kidney important
    • Na reabsorption causes water reabsorption
    • Na reabsorption coupled to reabsorption of organic and inorganic ions
    • Na reabsorption related to secretion of H and K
    • 80% of energy supports Na reabsorption
  77. where is 70% of water and Na reabsorbed
    PCT
  78. how is Na reabsorbed in the PCT
    • enters lumen by Na/solute cotransporters
    • exits by basolateral Na/K ATPase pumps
  79. what drives Na into the blood
    peritubular capillary Starling forces
  80. how does peritubular capillary starling forces fuxn
    tubules pressure is low do to the blood passing thru other vessels, favors the uptake of Na
  81. how much Na and water is reabsorbed in the Loop of Henle
    20% of Na and 10% of water
  82. why is less water reabsorbed in the loop of henle
    the ascending loop is impermeable to water
  83. how is Na reabsorbed in the loop of henle
    • reabsorption occurs through coupled transport of Na/K/Cl
    • exits by Na/K ATPase pump from the basolateral membrane
  84. why is less Na reabsorbed in the DCT and collecting ducts
    b/c of tight epithelial
  85. how much Na and water is reabsorbed in the DCT and collecting ducts
    9% of Na and 19% of water
  86. what controls the collecting ducts
    hormones
  87. what hormone stims Na reabsorption in the collecting duct
    aldosterone
  88. what is the reabsorption of Na in the collecting duct linked to
    Na/K exchanger
  89. what is the fuxn of ADH
    increase collecting duct permeability, causes more water reabsorption
  90. how does the lack of ADH affect Diabetes insipidus patients
    • less water reabsorbed causing freguent urination
    • 15-20L/day = polyuria
  91. what does the bowman's capsule surround
    glomerulus
  92. what causes the activation renal autoregulation
    BP/flow increases
  93. what refers to the rate of excretion of a substance divided by its plasma concentration
    renal plasma clearances
  94. where does active of absorption of Na occur
    PCT
  95. what does aldosterone and ADH act to increase
    reabsorption of Na and water
  96. secretion

    a. dependent upon Na/K ATPase pump
    b. requires both the descending and ascending limbs
    c. K is controlled by this process
    d. urea shows this
    e. is decreased with low MAP
    K is controlled by this process
  97. active reabsorption

    a. dependent upon Na/K ATPase pump
    b. requires both the descending and ascending limbs
    c. K is controlled by this process
    d. urea shows this
    e. is decreased with low MAP
    dependent upon Na/K ATPase pump
  98. countercurrent multiplication

    a. dependent upon Na/K ATPase pump
    b. requires both the descending and ascending limbs
    c. K is controlled by this process
    d. urea shows this
    e. is decreased with low MAP
    requires both ascending and descending limbs
  99. filtration

    a. dependent upon Na/K ATPase pump
    b. requires both the descending and ascending limbs
    c. K is controlled by this process
    d. urea shows this
    e. is decreased with low MAP
    is decreased with low MAP
  100. passive reabsorption

    a. dependent upon Na/K ATPase pump
    b. requires both the descending and ascending limbs
    c. K is controlled by this process
    d. urea shows this
    e. is decreased with low MAP
    urea show this
  101. principal

    a. releases renin
    b. has microvilli
    c. responds to ADH
    d. has fenestrae
    e. has foot processes
    responds to ADH
  102. tubular epithelial

    a. releases renin
    b. has microvilli
    c. responds to ADH
    d. has fenestrae
    e. has foot processes
    has microvilli
  103. glomerular capillary

    a. releases renin
    b. has microvilli
    c. responds to ADH
    d. has fenestrae
    e. has foot processes
    has fenestrae
  104. granular

    a. releases renin
    b. has microvilli
    c. responds to ADH
    d. has fenestrae
    e. has foot processes
    releases renin
  105. podocyte

    a. releases renin
    b. has microvilli
    c. responds to ADH
    d. has fenestrae
    e. has foot processes
    has foot processes
  106. how much body water is contained in the ECF and ICF
    • ECF - 1/3 of body water
    • ICF - 2/3 of body water
  107. what determines water distribution
    osmotic pressure
  108. what is the largest contributor to osmotic pressure of body fluids
    electrolytes
  109. what is osmotic pressure directly related to
    osmolality
  110. what is osmolality
    total solute conc.
  111. what is directly related to the amt of water in a compartment
    the amt of solute in that compartment
  112. what happens if solute conc. increases
    osmolality increases
  113. how does water move
    • water moves from lower osmolality to higher osmolality
    • water moves from lower osmotic pressure to higher OP
  114. what is equal in humans
    the OP of ECF and ICF
  115. what determines the volume of water in the ECF
    Na and its accompanying anions accounts for 90%
  116. what determines the volume of water in ICF
    K
  117. what do kidneys have a major role in
    balancing water, electrolytes, protons, and some organic cmpds.
  118. what are the 2 mechanisms of water balance
    hormonal and thirst
  119. how does hormonal water balance work
    ADH controls renal excretion of water
  120. how does the thirst mechanism of water balance work
    • osmoreceptors in the hypothalamus detect cellular hydration
    • signal cerebral cortex
    • you feel thirsty
  121. what may also stim thirst
    • blood vol receptors in CV system and kidneys
    • causes hypovolemia and
    • you fell thirsty
  122. what is responsible for 95% of total Na output
    urine
  123. what is closely related to Na balance
    ECF
  124. what controls Na excretion
    negative feedback system
  125. what mechanisms responds to changes in ECF vol
    • GFR
    • plasma aldosterone levels
    • renal SNS activity
    • Plasma ANP
    • peritubular capillary starling forces
    • intrarenal blood flow distribution
  126. how does GFR respond to changes in ECF vol
    increase of ECF <increase of GFR < increase in sodium excretion
  127. how does aldosterone react to changes in ECF vol
    decrease ECF vol <renin release<leads to angiotensin II< aldosterone< Na reabsorption
  128. how does ECF vol affect renal sns activity
    decrease of renal sodium excretion
  129. how does ECF vol affect ANP
    increase Na excretion
  130. how does ECF vol affect peritubular capillary starling forces
    increase Na excretion with increase in hydrostatic pressure or decrease of colloid osmotic pressure
  131. how does ECF vol affect intrarenal blood flow

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