Fluid Balance and Thirst Regulation Quiz
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Questions and Answers

Where is ADH synthesized?

  • In the thalamus
  • In magnocellular neurons of the supraoptic nuclei (correct)
  • In the kidney
  • In the posterior pituitary

    • What stimulates ADH release?

  • Decreased BP
  • Nausea
  • 10% change in ECF volume (correct)
  • 1% change in osmolarity

    • Which of the following factors decrease ADH secretion?

  • Increased blood pressure (arterial baroreceptors)
  • Alcohol
  • Decreased osmolarity
  • Increased blood volume (cardiopulmonary reflexes) (correct)

    • What is the homeostatic response to increased osmolarity?

    <p>Thirst and ADH</p> Signup and view all the answers

    What controls the thirst center in the brain?

    <p>Increased osmolarity</p> Signup and view all the answers

    What regulates the long-term volume regulation in blood pressure regulation by the kidney?

    <p>Thirst mechanism and fluid excretion</p> Signup and view all the answers

    What is the total GFR in normal kidneys?

    <p>125 mL/min</p> Signup and view all the answers

    What is the function of the countercurrent multiplier mechanism?

    <p>To produce a hyperosmotic renal medullary interstitium</p> Signup and view all the answers

    What is the role of the osmoreceptor-ADH feedback system?

    <p>To regulate water reabsorption in the kidneys</p> Signup and view all the answers

    What is the significance of the countercurrent exchanger of the vasa recta?

    <p>To maintain the osmotic gradient in the renal medulla</p> Signup and view all the answers

    What is the obligatory urine volume?

    <p>The minimum volume of urine that must be excreted to eliminate waste products</p> Signup and view all the answers

    What is the primary function of the kidneys in conserving water?

    <p>To excrete concentrated urine</p> Signup and view all the answers

    What stimulates the secretion of ADH (antidiuretic hormone)?

    <p>Increased blood osmolarity</p> Signup and view all the answers

    What is the role of thirst in controlling extracellular fluid osmolarity?

    <p>To prompt fluid intake in response to increased osmolarity</p> Signup and view all the answers

    What conditions are required for excreting concentrated urine?

    <p>High levels of ADH and a hyperosmotic renal medullary interstitium</p> Signup and view all the answers

    What is the main function of the countercurrent exchanger of the vasa recta?

    <p>To prevent the washout of the osmotic gradient in the renal medulla</p> Signup and view all the answers

    What is the range of urine osmolarity mentioned in the text?

    <p>50-70 mOsm/L</p> Signup and view all the answers

    What results in increased urine volume and dilution in the ascending loop of Henle?

    <p>Decreased ADH release</p> Signup and view all the answers

    What is the role of ADH in excreting concentrated urine?

    <p>Increased ADH release</p> Signup and view all the answers

    What is the function of the countercurrent multiplier in the tubule?

    <p>Trapping solutes in the renal medulla</p> Signup and view all the answers

    What happens to urea in the proximal tubule?

    <p>It is reabsorbed</p> Signup and view all the answers

    What controls the total body water according to the text?

    <p>Fluid intake regulation and renal water excretion</p> Signup and view all the answers

    What is the primary factor maintaining ECF osmolarity according to the text?

    <p>Na+ concentration</p> Signup and view all the answers

    What is the role of large molecules like glucose or protein in urine osmolarity?

    <p>Increase urine osmolarity</p> Signup and view all the answers

    What is the impact of renal disease on obligatory urine volume?

    <p>It may be increased</p> Signup and view all the answers

    What is the urine concentrating ability of humans compared to Australian hopping mice?

    <p>Limited, unlike Australian hopping mice</p> Signup and view all the answers

    Study Notes

    Role of Thirst in Fluid Balance

    • ECF osmolarity is maintained by Na+ as the largest ion in ECF, determined by solute/ECF volume
    • Total body water is controlled by fluid intake regulation and renal water excretion
    • Urine osmolarity ranges from 50-70 mOsm/L, influenced by the presence of large molecules like glucose or protein
    • Formation of dilute urine involves decreased ADH release and reduced water permeability in tubules
    • Renal response to ingestion of water results in increased urine volume and dilution in the ascending loop of Henle
    • Excreting concentrated urine requires increased ADH and high osmolarity of renal medulla
    • Obligatory urine volume is the minimum volume in which excreted solute can be dissolved and excreted
    • Humans have a limited urine concentrating ability, unlike Australian hopping mice
    • In renal disease, the obligatory urine volume may be increased due to impaired urine concentrating ability
    • Countercurrent multiplier manipulates solute and water in the tubule, trapping solutes in the renal medulla
    • Urea is reabsorbed in the proximal tubule and diffuses into the medullary interstitium, preserved by vasa recta
    • Different parts of the tubule reabsorb water and osmolarity at different rates, with ADH-dependent reabsorption in certain segments

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    Related Documents

    5.6UrineConcentrationandDilution.pptx

    Description

    Test your understanding of the role of thirst in fluid balance with this quiz. Explore topics such as ECF osmolarity, urine osmolarity, ADH release, urine concentration, and renal response to water ingestion. See how well you grasp the concepts of fluid intake regulation and renal water excretion.

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