CPR 51

    Cards (94)

    • What role do kidneys play in acid-base balance?
      They regulate plasma [HCO3-]
    • What happens to filtered HCO3- in the kidneys?
      It is completely reabsorbed
    • Where is HCO3- freely filtered in the kidneys?
      At the glomerulus
    • What do kidneys secrete to maintain acid-base balance?
      H+
    • What do protons associate with in urine?
      Urinary buffers like phosphate and ammonia
    • How is HCO3- formed in renal tubules?
      It can be newly formed in renal tubules
    • What replenishes HCO3- lost by buffering nonvolatile acids?
      Kidneys form new HCO3-
    • What types of acids do kidneys excrete?
      Sulfate and phosphate (non-volatile acids)
    • What is the process of bicarbonate reabsorption in the nephron?
      • All filtered HCO3- is reabsorbed
      • For every bicarbonate reabsorbed, one H+ is secreted
    • What enzyme is involved in the formation of carbonic acid in the proximal tubule?
      Carbonic anhydrase
    • What happens to carbonic acid in the proximal tubular cell?
      It dissociates into bicarbonate and proton
    • What is the relationship between proton secretion and bicarbonate reabsorption?
      For every proton secreted, one bicarbonate enters blood
    • What happens to the secreted proton in the tubular lumen?
      It associates with filtered bicarbonate to form carbonic acid
    • How much of the filtered bicarbonate is reabsorbed in the proximal tubule?
      85%
    • What are the two mechanisms that form new bicarbonate in the kidneys?
      • Phosphate buffer system
      • Ammonia buffer system
    • What is the role of the phosphate buffer in bicarbonate formation?
      It helps form new bicarbonate by buffering H+
    • How is acid phosphate excreted in urine?
      As titratable acid
    • What happens to ammonium in the urine?
      It is excreted as ammonium chloride
    • How does ammonia contribute to bicarbonate formation?
      Ammonia binds to protons to form ammonium
    • What stimulates the tubular capacity to form ammonium?
      Prolonged acidosis
    • What are the two types of ATPases involved in H+ secretion in the collecting duct?
      H+ ATPase and K+-H+ ATPase
    • What is the summary of bicarbonate reabsorption and formation in the kidneys?
      • HCO3- is filtered and reabsorbed
      • H+ is secreted to maintain balance
      • New HCO3- is formed via phosphate and ammonia buffers
    • What do secreted protons form with HPO4- in the collecting duct?
      Acid phosphate
    • What do beta-intercalated cells in the collecting duct do?
      They secrete HCO3- in urine
    • What happens during chronic alkalosis in the kidneys?
      They secrete bicarbonate lost in urine
    • How is urinary acid loss quantified?
      H+ in urine = Acid phosphate + Ammonium - Urinary Bicarbonate
    • What happens to H+ secretion during chronic acidosis?
      Increased H+ secretion in tubules
    • What is the total production of fixed H+ in normal conditions?
      50 mEq/day
    • What is the effect of increased PaCO2 on H+ secretion?
      It increases carbonic anhydrase activity
    • How does hypokalemia affect H+ secretion in renal tubules?
      It stimulates H+ secretion
    • What is the relationship between metabolic acidosis and serum potassium levels?
      Metabolic acidosis causes hyperkalemia
    • What happens to potassium levels during metabolic alkalosis?
      It causes hypokalemia
    • How does hypokalemia affect pH levels?
      It leads to alkalosis
    • What is the major intracellular cation?
      K+
    • How are K+ and H+ related?
      K+ and H+ are closely related
    • What is the plasma glucose level in diabetic ketoacidosis?
      400 mg/dL
    • What happens to K+ during insulin deficiency and hyperglycemia?
      K+ shifts from ICF to ECF
    • What is the result of increased serum K+ in diabetic ketoacidosis?
      Hyperkalemia
    • How do changes in pH affect serum K+ levels?
      Changes in pH affect serum (ECF) K+ levels
    • What is the effect of metabolic acidosis on serum potassium?
      Hyperkalemia
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