Renal Filtration and Barriers Quiz G27
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Questions and Answers

Under what pathological condition would increased pressure in Bowman's capsule most significantly reduce filtration?

  • Elevated arterial blood pressure
  • Increased efferent arteriolar resistance
  • Decreased afferent arteriolar resistance
  • Obstruction of the urinary tract (correct)

    • What is the approximate increase in plasma protein concentration as blood passes from the afferent arterioles to the efferent arterioles due to fluid removal during filtration?

  • 10%
  • 5%
  • 20% (correct)
  • 35%

    • What is the approximate average colloid osmotic pressure (oncotic pressure) in the glomerular capillaries?

  • $32 \text{ mm Hg}$ (correct)
  • $28 \text{ mm Hg}$
  • $36 \text{ mm Hg}$
  • $30 \text{ mm Hg}$

    • How does increasing the afferent arteriolar plasma colloid osmotic pressure affect the glomerular filtration rate (GFR)?

    <p>Decreases GFR (D)</p> Signup and view all the answers

    How does a reduction in renal plasma flow influence the glomerular filtration rate (GFR)?

    <p>Decreases GFR by increasing colloid osmotic pressure. (B)</p> Signup and view all the answers

    Which of the following factors directly increases glomerular hydrostatic pressure?

    <p>Increased efferent arteriolar resistance (C)</p> Signup and view all the answers

    What is the primary means for the physiological regulation of GFR?

    <p>Changes in glomerular hydrostatic pressure (A)</p> Signup and view all the answers

    What is the effect of slight constriction of the efferent arteriole on glomerular filtration?

    <p>Increased filtration through an increase in hydrostatic pressure. (C)</p> Signup and view all the answers

    What is the primary determinant of glomerular filtration rate (GFR) that is most susceptible to variability and control?

    <p>Glomerular hydrostatic pressure (D)</p> Signup and view all the answers

    Which segment of the renal vasculature does NOT contribute significantly to total renal vascular resistance?

    <p>Arcuate arteries (B)</p> Signup and view all the answers

    What is the effect of strong activation of renal sympathetic nerves on renal blood flow and GFR?

    <p>Causes vasoconstriction and decreases renal blood flow and GFR (D)</p> Signup and view all the answers

    Which of the following best describes the path of vasa recta through the kidney?

    <p>Descends into the medulla parallel with the loops of Henle and returns along the loop of Henle to the cortex before emptying into the venous system. (B)</p> Signup and view all the answers

    What is the approximate percentage of total renal blood flow that is directed to the renal medulla?

    <p>1% to 2% (A)</p> Signup and view all the answers

    How does mild to moderate stimulation of the sympathetic nervous system affect renal blood flow and GFR?

    <p>Has little influence on renal blood flow and GFR, but decreases sodium and water exrection (B)</p> Signup and view all the answers

    What happens to GFR if resistance increases more than threefold?

    <p>GFR decreases (B)</p> Signup and view all the answers

    What happens to Colloid osmotic pressure if resistance increases more than threefold?

    <p>Colloid osmotic pressure increases (C)</p> Signup and view all the answers

    Which of the following hormones does NOT typically contribute to vasoconstriction in renal blood vessels?

    <p>Nitric oxide (A)</p> Signup and view all the answers

    Angiotensin II raises glomerular hydrostatic pressure while reducing renal blood flow. What is the primary consequence of this combined effect?

    <p>Increased reabsorption of sodium and water (B)</p> Signup and view all the answers

    What is the primary mechanism by which nitric oxide induces vasodilation?

    <p>Converting GTP to cyclic GMP (C)</p> Signup and view all the answers

    Atherosclerosis is know to damage vascular endothelium. Damage to vascular endothelium is most likely to impair which of the following processes in the kidneys?

    <p>Nitric oxide production (B)</p> Signup and view all the answers

    Which of the following best describes the role of prostaglandins in the kidney?

    <p>Counteracting the effects of angiotensin II (C)</p> Signup and view all the answers

    Arginine stimulates nitric oxide production. What is the significance of nitric oxide being a gas in this process?

    <p>It can easily diffuse through cellular membranes. (D)</p> Signup and view all the answers

    Which of the following best describes the relationship between glomerular filtration rate (GFR), renal plasma flow, and filtration fraction?

    <p>Filtration fraction is directly proportional to GFR and inversely proportional to renal plasma flow. (C)</p> Signup and view all the answers

    In the kidneys, which blood vessels are particularly sensitive to the vasoconstrictive effects of angiotensin II?

    <p>Efferent arterioles (D)</p> Signup and view all the answers

    What is the approximate percentage of renal plasma flow that is filtered at the glomerular capillaries?

    <p>20% (A)</p> Signup and view all the answers

    Which structural characteristic of glomerular capillaries contributes most significantly to their high filtration rate?

    <p>The presence of fenestrations. (A)</p> Signup and view all the answers

    If a drug inhibits nitric oxide formation, what is the likely effect on renal vascular resistance and GFR?

    <p>Increased renal vascular resistance and decreased GFR (C)</p> Signup and view all the answers

    What is the primary reason plasma proteins are typically prevented from passing through the glomerular filtration barrier?

    <p>They are repelled by negative charges on the basement membrane and epithelial cells. (B)</p> Signup and view all the answers

    Which of the following is NOT a major layer of the capillary membrane involved in filtration?

    <p>Smooth Muscle Layer (D)</p> Signup and view all the answers

    The glomerular filtration rate is influenced primarily by which two factors?

    <p>Kidney blood flow and the properties of the glomerular capillary membranes. (C)</p> Signup and view all the answers

    How does the filtrate in Bowman's capsule typically compare to plasma in terms of composition?

    <p>The filtrate has similar concentrations of most constituents, except for protein-bound substances and larger proteins. (D)</p> Signup and view all the answers

    What is the approximate daily volume of fluid filtered by the glomerular capillaries into Bowman's capsule?

    <p>180 liters (A)</p> Signup and view all the answers

    What is the primary goal of autoregulation in most tissues of the body?

    <p>Maintaining the delivery of oxygen and nutrients and removing waste products of metabolism. (B)</p> Signup and view all the answers

    In the context of renal function, what is the consequence of a significant increase in GFR without a corresponding adjustment in tubular reabsorption?

    <p>A disproportionate increase in urine output, potentially leading to rapid fluid depletion. (A)</p> Signup and view all the answers

    What is the typical GFR (glomerular filtration rate) in liters per day?

    <p>180 liters/day (A)</p> Signup and view all the answers

    What would happen if blood pressure increases by only 25% and there was NO auto regulation?

    <p>GFR would increase to 225 liters/day. (A)</p> Signup and view all the answers

    What is the effect of cyclic GMP on smooth muscles?

    <p>It decreases calcium levels to cause relaxation of smooth muscles. (B)</p> Signup and view all the answers

    What is the normal mean arterial pressure range for the GFR to remain constant throughout?

    <p>Between 50 and 200 (C)</p> Signup and view all the answers

    What is the combined effect of pressure diuresis and pressure natriuresis crucial for?

    <p>The regulation of body fluid volumes and arterial pressure. (A)</p> Signup and view all the answers

    What happens to urinary output if you increase arterial pressure?

    <p>Urinary output increases (C)</p> Signup and view all the answers

    What is the primary goal of the tubuloglomerular feedback mechanism?

    <p>To stabilize sodium chloride delivery to the distal tubule. (D)</p> Signup and view all the answers

    Which anatomical feature is crucial for the tubuloglomerular feedback mechanism to function effectively?

    <p>The special location of the macula densa near the afferent and efferent arterioles. (B)</p> Signup and view all the answers

    What is the immediate effect of decreased GFR on sodium chloride concentration at the macula densa?

    <p>Decreased sodium chloride concentration due to increased reabsorption in the loop of Henle. (A)</p> Signup and view all the answers

    When the macula densa detects a decrease in $NaCl$ concentration, what signal is sent, and what are its effects?

    <p>It stimulates renin release and causes afferent arterioles to relax, increasing GFR. (D)</p> Signup and view all the answers

    Which cellular organelle within the macula densa plays a crucial role in secreting substances towards the arterioles, and what does this suggest about the function of these cells?

    <p>Golgi apparatus, suggesting secretory functions towards the arterioles. (C)</p> Signup and view all the answers

    How might angiotensin II affect the afferent and efferent arteriole resistance given the tubuloglomerular feedback system?

    <p>It constricts the efferent arteriole, increasing resistance and maintaining GFR under low perfusion pressure. (C)</p> Signup and view all the answers

    What is the impact of increased sodium chloride concentration at the macula densa on renin release and afferent arteriole tone?

    <p>Decreased renin release and constriction of the afferent arteriole. (A)</p> Signup and view all the answers

    What is the relationship between renal blood flow and GFR in the context of tubuloglomerular feedback?

    <p>GFR may be regulated at the expense of renal blood flow to stabilize sodium chloride delivery to the distal tubule. (C)</p> Signup and view all the answers

    Study Notes

    Renal Filtration

    • 180 liters of blood are filtered daily from glomerular capillaries to Bowman's capsule
    • Most filtered fluid is reabsorbed, leaving 1 liter for excretion
    • Filtration rate is variable and depends on factors like fluid intake and kidney blood flow
    • Glomerular capillaries are relatively impermeable to proteins and red blood cells
    • Concentration of other constituents are similar to plasma, except for substances bound to plasma proteins
    • Capillary filtration rate (GFR) is about 20% of renal plasma flow
    • Filtration fraction is the ratio that can be increased by increasing GFR or decreased by decreasing renal plasma flow, averaging 0.2

    Filtration Barrier

    • Composed of three layers: endothelium, basement membrane, and epithelial cells
    • Endothelium has fenestrae (small holes) like those in liver capillaries
    • Cell proteins are hindered by negative charges in the basement membrane, which allows water and small solutes to pass
    • Slit pores in epithelial cells also prevent larger molecules
    • Filtration is selective based on size and electrical charge
    • Water is freely filtered, whereas larger molecules like albumin have low filterability

    Determining GFR

    • GFR is determined by the sum of forces (hydrostatic and colloid osmotic) and the filtration coefficient
    • Hydrostatic pressure in capillaries favors filtration; colloid osmotic pressure opposes it
    • Net filtration pressure and the filtration coefficient determine GFR
    • Changes in glomerular hydrostatic pressure are the main mechanism for physiologic regulation of GFR
    • Increased arterial pressure - raises GFR
    • Increased afferent arteriole resistance - decreases GFR
    • Changes in colloid osmotic pressures, or plasma proteins in the glomerular capillary or Bowman's capsule
    • Changes to renal plasma flow also impact GFR

    Autoregulation

    • Kidneys maintain a steady GFR despite fluctuation in system blood pressure
    • Special feedback mechanism links sodium chloride concentration and control of renal arterial resistance
    • Maintaining constant delivery of sodium chloride to distal tubule is the goal
    • Feedback mechanism involves a macula densa located in the distal tubule
    • Macula densa is close to afferent and efferent arterioles
    • Decreased GFR causes increased sodium release and relaxation of the afferent arterioles

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    Glomerular Filtration, Renal Blood Flow, PDF

    Description

    Test your knowledge on the renal filtration process and the filtration barrier's structure. This quiz covers the mechanics of blood filtration, the glomerular filtration rate (GFR), and the components of the filtration barrier. Dive in to review important renal physiology concepts!

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