Biology Forums - Study Force

Which correctly describes renin?
 
  A. It is secreted by juxtaglomerular cells in renal afferent arterioles.
  B. Its secretion is enhanced by high levels of Na+ in the macula densa.
  C. Its secretion is stimulated by elevated blood pressure in the renal afferent arterioles.
  D. It acts on the adrenal cortex to stimulate aldosterone secretion.
  E. It is secreted by the liver in response to low blood pressure.

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(Question 2) Which of the following most accurately describes the renal transport of Na+?
 
  A. Na+ is actively transported in all segments of the tubule.
  B. Primary active transport of Na+ allows for secondary active transport of glucose and H+ in the proximal tubule.
  C. Most of the Na+ transport occurs in the distal convoluted tubule and collecting ducts.
  D. Na+ is actively secreted into the nephron lumen by cells in the cortical collecting ducts.
  E. Na+ is actively transported across the luminal membrane of proximal tubule cells in exchange for K+, by Na+/K+ ATPase pumps.

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(Question 3) Which of these is deficient in the disease, diabetes insipidus?
 
  A. ACTH
  B. vasopressin
  C. atrial natriuretic factor
  D. angiotensin II
  E. insulin

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(Question 4) Which would occur if a person lost the ability to synthesize vasopressin?
 
  A. The ability to reabsorb water in the proximal tubule would be lost.
  B. The excretion of glucose in the urine would increase.
  C. The urine would become hypoosmotic compared to plasma.
  D. The urine production would decrease dramatically, and the urine osmolarity would be hypertonic compared to plasma.
  E. Blood pressure would increase significantly.

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(Question 5) What region of the nephron reabsorbs about two-thirds of filtered Na+ and Cl-?
 
  A. ascending loop of Henle
  B. glomerulus
  C. proximal convoluted tubule
  D. distal convoluted tubule
  E. collecting duct

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(Question 6) Water and NaCl reabsorbed from the loop of Henle directly reenter what blood vessels?
 
  A. vasa recta
  B. afferent arterioles
  C. efferent arterioles
  D. cortical peritubular capillaries
  E. collecting ducts

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(Question 7) Which is TRUE about the hormone vasopressin (also known as antidiuretic hormone, ADH)?
 
  A. It is a peptide hormone released from the adrenal gland.
  B. It triggers insertion of aquaporins into the apical membranes of collecting duct cells.
  C. It promotes the excretion of more water in the urine.
  D. It stimulates the excretion of K+ in the urine.
  E. Its main function is to trigger the secretion of aldosterone.

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(Question 8) In the condition diabetes mellitus, why does glucose appear in the urine?
 
  A. The plasma concentration of glucose becomes so high that it diffuses from peritubular capillaries into the proximal tubule, down its concentration gradient.
  B. The filtered load of glucose becomes greater than the tubular maximum for its reabsorption.
  C. Without the hormone insulin, glucose cannot enter proximal tubule epithelial cells.
  D. The rate of tubular secretion of glucose becomes greater than the sum of glucose filtration and reabsorption.
  E. Without insulin, the glomerular filtration barrier becomes extremely leaky to glucose, which is not normally filterable.

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(Question 9) How does the renal countercurrent multiplier mechanism allow the creation of a concentrated urine?
 
  A. It transports NaCl from the medullary interstitium into the collecting duct, which directly increases the osmolarity of the urine.
  B. It transports urea from the medullary interstitium into the collecting duct, which directly increases the osmolarity of the urine.
  C. By concentrating NaCl in the renal medullary interstitium, it allows water to be reabsorbed from the collecting ducts when vasopressin is present.
  D. By pumping NaCl and urea into the ascending limb of the loop of Henle, it raises the solute load, which turns into a concentrated urine once water is extracted from the collecting duct.
  E. When anti-diuretic hormone is present, it stimulates the pumping of NaCl from the medullary interstitium and water follows, concentrating the urine.

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(Question 10) In which region of the nephron does the fractional reabsorption of water vary the most in response to variation in the state of hydration?
 
  A. the glomerulus
  B. the proximal convoluted tubule
  C. the loop of Henle
  D. the distal convoluted tubule
  E. the collecting duct

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