Ch14 urinary system
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What type of cells are found in the distal convoluted tubule that respond to changes in solute concentration of the filtrate?

  • Glomerular cells
  • Vasa recta cells
  • Macula densa cells (correct)
  • Juxtaglomerular cells

    • What is the main function of the vasa recta?

  • To regulate the glomerular filtration rate
  • To filter out waste and water from the glomerular capillary
  • To form a bundle of long straight vessels (correct)
  • To secrete vasoconstriction substances

    • What is the first step in urine formation?

  • Tubular reabsorption
  • Tubular secretion
  • Urinary excretion
  • Glomerular filtration (correct)

    • What is the equation for urinary excretion?

    <p>Glomerular filtration - Tubular reabsorption</p> Signup and view all the answers

    Why are glomerular capillaries more permeable than capillaries in other tissues?

    <p>Because of their special function in filtration</p> Signup and view all the answers

    What is the net force acting to move material out of the glomerulus and into the glomerular capsule?

    <p>Filtration pressure</p> Signup and view all the answers

    What is the mechanism of neural regulation of GFR?

    <p>Sympathetic nerves constrict the afferent arteriole</p> Signup and view all the answers

    What is the function of the juxtaglomerular apparatus (JGA) in regulating GFR?

    <p>To secrete vasoconstriction substances to the afferent arteriole</p> Signup and view all the answers

    What is the primary function of the urinary system in relation to waste removal?

    <p>Removing waste material from the blood plasma and disposing of it in the urine</p> Signup and view all the answers

    Which of the following organs is responsible for blood filtering and urine formation?

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

    What is the function of the renal cortex?

    <p>Housing most nephrons</p> Signup and view all the answers

    What is the role of the renal calyx in the urinary system?

    <p>Collecting urine from nephrons and directing it into the renal pelvis</p> Signup and view all the answers

    What is the function of the ureter in the urinary system?

    <p>Transporting urine from the kidney to the urinary bladder</p> Signup and view all the answers

    What is the main role of the urinary bladder in the urinary system?

    <p>Storing up to 400 ml of urine</p> Signup and view all the answers

    Which of the following is NOT a function of the urinary system?

    <p>Digestion of food</p> Signup and view all the answers

    What is the function of the renal medulla in the urinary system?

    <p>Collecting urine from nephrons</p> Signup and view all the answers

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

    <p>Filtration of H2O and dissolved substances from the plasma</p> Signup and view all the answers

    Which of the following substances is reabsorbed by active transport in the proximal convoluted tubule?

    <p>Glucose and amino acids</p> Signup and view all the answers

    What is the primary function of the juxtaglomerular apparatus?

    <p>Detection of changes in blood pressure and secretion of renin</p> Signup and view all the answers

    Which of the following is NOT a function of the proximal convoluted tubule?

    <p>Secretion of insulin</p> Signup and view all the answers

    What is the primary function of the ascending limb of the nephron loop?

    <p>Reabsorption of Na, K, and Cl- by active transport</p> Signup and view all the answers

    What is the primary function of the distal convoluted tubule?

    <p>Reabsorption of Na by active transport</p> Signup and view all the answers

    What is the mechanism by which the proximal convoluted tubule reabsorbs proteins?

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

    What is the primary function of the collecting duct?

    <p>Reabsorption of H2O by osmosis</p> Signup and view all the answers

    What is the primary effect of ADH on the distal convoluted tubules and collecting ducts?

    <p>Increase H2O reabsorption by osmosis</p> Signup and view all the answers

    What happens to urine volume when ADH is present?

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

    What are the three major processes involved in urine formation and adjustment of blood composition?

    <p>Filtration, reabsorption, and secretion</p> Signup and view all the answers

    What is the primary function of the preritubular capillary?

    <p>Reabsorption of solutes</p> Signup and view all the answers

    What mode of transport is used to reabsorb glucose and amino acids in the proximal tubule?

    <p>Active transport</p> Signup and view all the answers

    What is the driving force behind water reabsorption in the proximal tubule?

    <p>Osmotic pressure</p> Signup and view all the answers

    What is the osmolarity of the fluid entering the loop of Henle?

    <p>100 mosm/l</p> Signup and view all the answers

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

    <p>To establish a horizontal gradient of osmolarity</p> Signup and view all the answers

    What is the direction of Na+ movement in the ascending limb?

    <p>Passively out of the tubular fluid into interstitial fluid</p> Signup and view all the answers

    What is the reason for the increase in osmolarity in the ISF as you go deeper in the medulla?

    <p>NaCl concentration increases in the descending limb</p> Signup and view all the answers

    What is the characteristic of the descending limb in the loop of Henle?

    <p>Permeable to H2O and no active transport of ions</p> Signup and view all the answers

    What is the result of active pumping of salt out of the ascending limb?

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

    What happens to the fluid in the ascending limb as you go up?

    <p>Osmolarity decreases</p> Signup and view all the answers

    What is the net overall result in the ISF as one progresses from the beginning to the end in the loop of Henle?

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

    What happens to H2O in the descending limb?

    <p>Moves passively out of the descending limb into the ISF</p> Signup and view all the answers

    What is the result of the mechanisms in the loop of Henle?

    <p>More fluid has been reabsorbed from the original volume of glomerular filtrate</p> Signup and view all the answers

    Study Notes

    Functions of the Urinary System

    • Excretion: removal of waste material from blood plasma and disposal of waste in urine
    • Elimination: removal of waste from other organ systems
    • Water balance: kidney tubules regulate water reabsorption and urine concentration
    • Regulation of pH: volume, and composition of body fluids
    • Production of erythropoietin for hematopoiesis and renin for blood pressure regulation

    Anatomy of the Urinary System

    • Kidneys: pair of bean-shaped organs located retroperitoneally, responsible for blood filtering and urine formation
    • Renal capsule: layer of fibrous connective tissue covering the kidneys
    • Renal cortex: outer region of the kidneys where most nephrons are located
    • Renal medulla: inner region of the kidneys where some nephrons are located, and urine is collected to be excreted outward
    • Renal calyx: duct-like sections of renal medulla for collecting urine from nephrons and directing urine into renal pelvis
    • Renal pyramid: connective tissues in the renal medulla binding various structures together
    • Renal pelvis: central urine collecting area of renal medulla
    • Hilum: concave notch of kidneys where renal artery, renal vein, ureter, nerves, and lymphatic vessels converge
    • Ureter: tubule that transports urine (mainly by peristalsis) from the kidney to the urinary bladder
    • Urinary bladder: spherical storage organ that contains up to 400 ml of urine

    Functions of Nephron Components

    • Renal capsule: filteration of H2O and dissolved substances from the plasma
    • Glomerulus: filtration of H2O and dissolved substances from the plasma
    • Glomerular capsule: receives the glomerular filtrate
    • Proximal convoluted tubule:
      • Reabsorption of glucose, amino acids, creatine, lactic acid, citric acid, uric acid, and ascorbic acid by active transport
      • Reabsorption of proteins by pinocytosis
      • Reabsorption of H2O by osmosis
      • Reabsorption of Cl- and other negatively charged ions by electrochemical attraction
      • Active secretion of substances such as penicillin and hydrogen ions
    • Descending limb of nephron loop: reabsorption of H2O by osmosis
    • Ascending limb of nephron loop: reabsorption of Na, K, and Cl- by active transport
    • Distal convoluted tubule:
      • Reabsorption of Na by active transport
      • Reabsorption of H2O by osmosis
      • Active secretion of hydrogen ions
      • Secretion of K both actively and by electrochemical attraction
    • Collecting duct: reabsorption of H2O by osmosis

    Juxtaglomerular Apparatus

    • Located at the point of contact between the distal convoluted tubule and the afferent and efferent arterioles
    • JG cells detect changes in blood pressure in the afferent arterioles and secrete renin
    • Macula densa cells respond to changes in the solute concentration of the filtrate in the tubule

    Glomerular Filtration

    • Urine formation begins when waste and water and dissolved materials are filtered out of the glomerular capillary
    • Urinary excretion = glomerular filtration + Tubular secretion - Tubular reabsorption
    • Glomerular capillaries are much more permeable than capillaries in other tissues
    • Filtration pressure = forces favoring filtration (Glomerular capillary hydrostatic pressure & capsular osmotic pressure) - forces opposing filtration (capsular hydrostatic pressure & Glomerular capillary osmotic pressure)

    Regulation of GFR

    • Neural regulation: sympathetic nerves can cause the constriction or relaxation of the afferent arteriole, resulting in a change of GFR
    • Renal autoregulation: the juxtaglomerular apparatus secretes vasoconstriction substances to either afferent arteriole, in response to GFR changes and NaCl levels
    • ADH causes the distal convoluted tubules and collecting ducts to become more permeable and increase H2O reabsorption by osmosis

    Mechanism of forming dilute & concentrated urine

    • Urine formation and adjustment of blood composition involves three major processes: Glomerular filtration, Tubular reabsorption, and Secretion
    • Tubular reabsorption: the kidney must have mechanisms for reabsorption of the many solutes (Na+, K+, glucose, chloride -) and H2O that it filters each day
    • Substances are selectively reabsorbed from the glomerular filtrate
    • The peritubular capillary is adapted for reabsorption, carrying low-pressure blood and being very permeable
    • Most reabsorption (70%) occurs in the proximal tubule
    • Different modes of transport reabsorb various substances in particular segments of the renal tubule

    Countercurrent Mechanism

    • The fluid entering the loop of Henle has an osmolarity of 100 mosm/l
    • The descending limb is very permeable to H2O, and Na+ and Cl- ions are reabsorbed
    • The ascending limb is impermeable to H2O but actively transports Cl- out of the tubular fluid into interstitial fluid, with Na+ ion following passively
    • Thus, a small horizontal gradient of 200 is established between the ascending and descending limbs

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    Chap 14 Urinary System PDF

    Description

    This quiz covers the functions of the urinary system, including excretion and elimination of waste materials from the blood plasma and other organ systems.

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