physiology 1404 lect 4
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Questions and Answers

What percentage of the body is composed of water?

  • 60% (correct)
  • 40%
  • 70%
  • 50%

    • Which of the following is NOT a regulated route of water loss?

  • Sweating
  • Evaporation from the lungs
  • Renal excretion (correct)
  • Defecation

    • When the intake of water is greater than the loss of water, what is the resulting water balance?

  • Negative water balance
  • Osmotic equilibrium
  • Positive water balance (correct)
  • Neutral water balance

    • What is the osmolarity of urine when the kidneys conserve water?

    <p>1200 mOsm/kg H2O</p> Signup and view all the answers

    What percentage of the body is composed of intracellular fluid (ICF)?

    <p>40%</p> Signup and view all the answers

    When the kidneys conserve water, what is the resulting urine volume?

    <p>0.5 L/day</p> Signup and view all the answers

    What percentage change in body fluid osmolarity can alter the secretion of ADH?

    <p>1%</p> Signup and view all the answers

    Where are the osmoreceptors located that sense changes in body fluid osmolarity?

    <p>Anterior hypothalamus</p> Signup and view all the answers

    What happens to circulating ADH levels when secretion is inhibited?

    <p>They are reduced to zero within minutes</p> Signup and view all the answers

    What is the normal range of set point for plasma osmolarity in individuals?

    <p>275-290 mOsm/kg H2O</p> Signup and view all the answers

    What can affect the set point of the ADH secretion system?

    <p>Changes in blood volume and blood pressure</p> Signup and view all the answers

    What is the primary function of the kidneys in terms of water balance?

    <p>Maintaining a constant solute load in body fluids</p> Signup and view all the answers

    What is the main mechanism by which the kidneys regulate urine concentration and volume?

    <p>Countercurrent multiplication and urea recycling</p> Signup and view all the answers

    What is the osmotic gradient in the interstitial fluid of the kidneys?

    <p>300 mOsm to 1200 mOsm/Kg H2O</p> Signup and view all the answers

    What is the role of antidiuretic hormone (ADH) in the kidneys?

    <p>Facilitating water reabsorption in the collecting ducts</p> Signup and view all the answers

    What is the solute load of body fluids that the kidneys aim to maintain?

    <p>300 mOsm/L</p> Signup and view all the answers

    What is the name of the process by which the kidneys concentrate urine?

    <p>Countercurrent multiplication</p> Signup and view all the answers

    What is the primary function of the thick ascending limb of the loop of Henle?

    <p>To decrease the osmolarity of the tubular fluid and increase the osmolarity of the surrounding interstitial fluid</p> Signup and view all the answers

    What is the osmolarity of the new fluid that enters the descending limb of the loop of Henle?

    <p>300 mOsm/L</p> Signup and view all the answers

    What is the result of the 'single effect' in the countercurrent multiplier?

    <p>The osmolarity of the ascending limb decreases, and the osmolarity of the descending limb increases</p> Signup and view all the answers

    What is the purpose of the countercurrent multiplier in the loop of Henle?

    <p>To create a gradient of osmolarity along the loop of Henle</p> Signup and view all the answers

    What happens to the high osmolarity fluid in the descending limb as a result of the flow of tubular fluid?

    <p>It is pushed down towards the bend of the loop of Henle</p> Signup and view all the answers

    What happens to the osmolarity of the interstitial fluid and descending limb in LoH Step 3?

    <p>It increases</p> Signup and view all the answers

    What is the direction of water flow in the descending limb of the loop of Henle?

    <p>From the tubular fluid to the surrounding interstitial fluid</p> Signup and view all the answers

    What is the osmolarity of the new fluid that enters the descending limb from the PT in LoH Step 4?

    <p>300 mOsm/L</p> Signup and view all the answers

    What is the constant difference in filtrate concentration between the 2 limbs of the LoH?

    <p>200 mOsm</p> Signup and view all the answers

    What happens to the fluid in the ascending limb as a result of the fluid shift in LoH Step 4?

    <p>It is pushed downward towards the bend of the LoH</p> Signup and view all the answers

    What is the role of the NaCl pumps in the ascending limb?

    <p>To create a constant difference in filtrate concentration between the 2 limbs of the LoH</p> Signup and view all the answers

    What is the result of the fluid shift in LoH Step 4 on the gradient of osmolarity?

    <p>It increases</p> Signup and view all the answers

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