Nephron Physiology Quiz
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Questions and Answers

What is the primary function of the glomerulus in a nephron?

  • Filtration of a protein-free plasma into the tubular component (correct)
  • Reabsorption of sodium and water
  • Exchanges with the fluid in the tubular lumen
  • Production of substances involved in kidney function control

    • What percentage of reabsorption occurs in the Proximal Convoluted Tubule (PCT)?

  • 50%
  • 25%
  • 80%
  • 65% (correct)

    • What is the main function of the Loop of Henle?

  • Establishing an osmotic gradient in the renal medulla (correct)
  • Reabsorption of sodium and water
  • Filtration of a protein-free plasma into the tubular component
  • Production of substances involved in kidney function control

    • What is the function of the Peritubular capillaries?

    <p>Supply the renal tissue; involved in exchanges with the fluid in the tubular lumen</p> Signup and view all the answers

    What is the function of the Afferent arteriole?

    <p>Carries blood to the glomerulus</p> Signup and view all the answers

    What is the function of the Distal tubule and Collecting duct?

    <p>Variable, controlled reabsorption of Na+ and H2O and secretion of K+ and H+</p> Signup and view all the answers

    What is the location of Cortical nephrons?

    <p>Entirely in the cortex</p> Signup and view all the answers

    What is the net glomerular filtration pressure?

    <p>+10mmHg</p> Signup and view all the answers

    What is the function of the Juxtaglomerular apparatus?

    <p>Produces substances involved in the control of kidney function</p> Signup and view all the answers

    What is the normal daily average glomerular filtration rate (GFR) in mL/min?

    <p>115-125</p> Signup and view all the answers

    Which of the following factors decreases the glomerular filtration rate (GFR)?

    <p>Sympathetic stimulation</p> Signup and view all the answers

    What is the main factor that determines the rate of glomerular filtration?

    <p>Both net filtration pressure and properties of the glomerular membrane</p> Signup and view all the answers

    What is the hydrostatic pressure in Bowman's capsule?

    <p>15mmHg</p> Signup and view all the answers

    Which of the following is NOT a factor that decreases the glomerular filtration rate (GFR)?

    <p>Parasympathetic stimulation</p> Signup and view all the answers

    What is the primary function of glomerular filtration?

    <p>To separate large proteins and cells from small substances</p> Signup and view all the answers

    What is the main driving force behind glomerular filtration?

    <p>The glomerular capillary blood pressure</p> Signup and view all the answers

    What is the purpose of the tubular reabsorption process?

    <p>To selectively return valuable substances to the blood</p> Signup and view all the answers

    What is the function of the podocyte cells in the glomerular membrane?

    <p>To form the filtration slits</p> Signup and view all the answers

    What is the result of glomerular filtration?

    <p>Water, ions, and small molecules enter the nephron tubules</p> Signup and view all the answers

    What is the name of the structure where the filtrate enters the nephron tubules?

    <p>Bowman's capsule</p> Signup and view all the answers

    What is the function of the basement membrane in the glomerular membrane?

    <p>To act as a gelatinous layer</p> Signup and view all the answers

    What is the value of the glomerular capillary blood pressure?

    <p>55mmHg</p> Signup and view all the answers

    What is the function of the ureters?

    <p>To transport urine from the kidney to the bladder</p> Signup and view all the answers

    What is the trigone of the urinary bladder?

    <p>Three openings in the bladder</p> Signup and view all the answers

    What affects the glomerular filtration rate (GFR) through changes in plasma protein concentration?

    <p>Pop</p> Signup and view all the answers

    What is the function of antidiuretic hormone (ADH)?

    <p>To prevent excessive water loss in urine</p> Signup and view all the answers

    What is the primary mechanism that maintains constant GFR despite changes in mean systemic arterial blood pressure (MAP)?

    <p>Autoregulation</p> Signup and view all the answers

    What is the normal pH range for blood?

    <p>7.35 to 7.45</p> Signup and view all the answers

    What is the result of increased Pglom on the afferent arteriole?

    <p>Vasoconstriction</p> Signup and view all the answers

    What is the function of the bicarbonate buffer system?

    <p>To maintain blood pH by reacting to changes in hydrogen ion concentration</p> Signup and view all the answers

    What is the role of the macula densa in tubuloglomerular feedback?

    <p>Releases ATP and adenosine to cause afferent arteriole vasoconstriction</p> Signup and view all the answers

    How does the respiratory system control acid-base balance?

    <p>By converting carbon dioxide to bicarbonate ion and transporting it in the plasma</p> Signup and view all the answers

    What is the effect of sympathetic nervous system stimulation on GFR?

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

    What is the function of the internal urethral sphincter?

    <p>To involuntarily release urine from the body</p> Signup and view all the answers

    What is the primary function of tubular reabsorption?

    <p>To return needed substances from the glomerular filtrate back to the blood</p> Signup and view all the answers

    Why are urinary infections more common in women than men?

    <p>Because the urethra is shorter in women</p> Signup and view all the answers

    What percentage of water is reabsorbed in the proximal convoluted tubule (PCT)?

    <p>8%</p> Signup and view all the answers

    What is the function of the detrusor muscle?

    <p>To contract and relax the bladder wall to facilitate urine storage</p> Signup and view all the answers

    At what age does the control of the voluntary urethral sphincter start?

    <p>At 18 months</p> Signup and view all the answers

    What is the role of vasopressin (ADH) in regulating water reabsorption?

    <p>Inserts aquaporins into the DCT and Collecting Duct to increase water reabsorption</p> Signup and view all the answers

    What is the normal pH of urine due to H+ secretion?

    <p>6</p> Signup and view all the answers

    What happens when two drugs that use the same carrier for elimination are taken together?

    <p>Neither drug is fully eliminated</p> Signup and view all the answers

    Study Notes

    Nephron Physiology

    • A nephron is the functional unit of the kidney, containing specialized blood vessels and tubules that regulate the exchange of materials between the blood and the body.
    • The nephron consists of:
      • Afferent arteriole: carries blood to the glomerulus
      • Glomerulus: a tuft of capillaries that filters a protein-free plasma into the tubular component
      • Efferent arteriole: carries blood from the glomerulus
      • Peritubular capillaries: supply the renal tissue and are involved in exchanges with the fluid in the tubular lumen
      • Proximal convoluted tubule (PCT): uncontrolled reabsorption and secretion of selected substances occur here
      • Loop of Henle: establishes an osmotic gradient in the renal medulla that is important for producing urine of varying concentration
      • Distal convoluted tubule (DCT) and collecting duct: variable, controlled reabsorption of Na+ and H2O and secretion of K+ and H+ occur here

    Types of Nephrons

    • Cortical nephrons: located entirely in the cortex, account for most nephrons
    • Juxtamedullary nephrons: found at the boundary of the cortex and medulla

    Nephron Processes

    • 3 main processes in the nephron:
      1. Glomerular filtration: separation of cells and large proteins from plasma
      2. Tubular reabsorption: valuable substances are selectively returned to the blood
      3. Tubular secretion: unneeded substances are selectively removed from the blood and added to the nephron

    Glomerular Filtration

    • Glomerular filtration is the nonspecific separation of large substances (cells, proteins) from small substances (water, ions, small molecules)
    • Blood enters at the afferent arteriole, passes through the glomerular membrane, and exits at the efferent arteriole
    • The glomerular membrane consists of:
      • Glomerular capillary wall: simple squamous epithelium with large pores (fenestrations)
      • Basement membrane: collagen and glycoprotein gelatinous layer
      • Capsular filtration slits: podocyte cells with processes link together to form filtration slits

    Glomerular Filtration Pressure

    • Glomerular filtration pressure is regulated by various pressures at the glomerular membrane:
      • Pglom (glomerular capillary blood pressure): 55 mmHg
      • Pop (plasma-colloid osmotic pressure): 30 mmHg
      • PBC (Bowman's capsule hydrostatic pressure): 15 mmHg
    • Net glomerular filtration pressure: +10 mmHg

    Glomerular Filtration Rate (GFR)

    • GFR is the rate of glomerular filtration and is important for assessing kidney health and disease
    • Factors affecting GFR:
      • Net filtration pressure (Pglom, Pop, PBC)
      • Properties of the glomerular membrane (pore size, filtration slit size)
    • GFR can be altered by:
      • Plasma protein concentration (affects Pop)
      • Hydration level (affects Pglom and PBC)
      • Urinary tract obstruction (PBC)
      • Mean arterial blood pressure (MAP affects Pglom)

    GFR Regulation

    • Autoregulation: the main way kidneys maintain a constant GFR as MAP changes
      • Myogenic mechanism: afferent arteriole constricts or dilates in response to changes in MAP
      • Tubuloglomerular feedback: macula densa senses changes in GFR and releases ATP and adenosine to constrict or dilate the afferent arteriole
    • Sympathetic nervous system stimulation decreases GFR to decrease urine volume and retain fluids

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    Description

    Test your knowledge on nephron structure and function, including renal corpuscle, glomerulus, and tubules.

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