All of the following substances are present in proximal tubular fluid in the kidney, but which one is NOT normally present in urine?

a. Ca²⁺

b. H⁺

c. K⁺

d. HPO₄ ^2-

e. Glucose

e. Glucose

Which one of the following substances is LEAST dependent on the kidney for regulation of its plasma concentration?

a. Water

b. Na⁺

c. K⁺

d. HPO₄ ^2-

e. Glucose

e. Glucose

Which of the following statements concerning the process of glomerular filtration is correct?

a. The hydrostatic pressure in Bowman's space opposes filtration.

b. The glomerular filtration rate is limited by a transport maximum.

c. All of the plasma that enters the glomerular capillaries is filtered.

d. The osmotic force due to plasma proteins favors filtration.

e. The hydrostatic pressure in glomerular capillaries opposes filtration.

a. The hydrostatic pressure in Bowman's space opposes filtration.

Constriction of the __________ decreases hydrostatic pressure in __________.

a. afferent arterioles; glomerular capillaries

b. efferent arterioles; proximal convoluted tubules

c. renal vein; peritubular capillaries

d. efferent arterioles; glomerular capillaries

e. efferent arterioles; Bowman's capsule

a. afferent arterioles; glomerular capillaries

Which is TRUE regarding renal tubular reabsorption?

a. Reabsorption of Na⁺ from the proximal tubule occurs as a result of water reabsorption.

b. Reabsorption of glucose saturates at a maximum transport rate.

c. Urea reabsorption cannot occur at any point along the nephron.

d. Toxic substances are removed from the body by reabsorption from peritubular capillaries into the proximal tubule.

e. Reabsorption of Na⁺ only occurs from nephron regions that come after the descending limb of the loop of Henle.

b. Reabsorption of glucose saturates at a maximum transport rate.

Which of the following describes tubular reabsorption in the kidney?

a. The movement of substances from the peritubular capillaries into the tubular fluid

b. The movement of substances from the proximal tubule into the loop of Henle

c. Transepithelial transport from the lumen of the tubule into renal interstitial fluid

d. Movement of Na⁺, Cl^-, and water from glomerular capillaries into Bowman's capsule

e. Transport of solutes from the renal medullary interstitial fluid into the collecting duct

c. Transepithelial transport from the lumen of the tubule into renal interstitial fluid

Which of the following is TRUE about how water is handled by the nephron?

a. Water is filtered out of glomerular capillaries by bulk flow.

b. Water is actively reabsorbed from the proximal tubule, and Na⁺ follows down its diffusion gradient.

c. Water is actively secreted into the descending loop of Henle.

d. The permeability of the ascending limb of the loop of Henle is modified by vasopressin.

e. Vasopressin inserts pumps in the collecting duct membrane that move water against its concentration gradient.

a. Water is filtered out of glomerular capillaries by bulk flow.

In what segment of the nephron is the greatest fraction of filtered water reabsorbed?

a. The proximal tubule

b. The ascending limb of the loop of Henle

c. The distal convoluted tubule

d. The collecting ducts

e. The descending limb of the loop of Henle

a. The proximal tubule

Which is NOT true about the countercurrent multiplier system of the kidney?

a. It creates a hyperosmolar medullary interstitial fluid that allows the kidneys to form hypertonic urine.

b. The descending loop of Henle is permeable to water.

c. There is active transport of sodium and chloride out of the ascending limb of the loop of Henle.

d. The ascending loop of Henle is not permeable to water.

e. The fraction of filtered NaCl reabsorbed from the ascending limb equals the fraction of filtered water reabsorbed from the descending limb.

e. The fraction of filtered NaCl reabsorbed from the ascending limb equals the fraction of filtered water reabsorbed from the descending limb.

Water and NaCl reabsorbed from the loop of Henle directly reenter which blood vessels?

a. Vasa recta

b. Afferent arterioles

c. Efferent arterioles

d. Cortical peritubular capillaries

e. Collecting ducts

a. Vasa recta

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.

b. It triggers insertion of aquaporins into the apical membranes of collecting duct cells.

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

c. Proximal convoluted tubule

What is the rate-limiting (regulated) step for stimulating the secretion of aldosterone?

a. Conversion of angiotensin I to angiotensin II in the blood

b. Secretion of angiotensinogen by the liver

c. Conversion of angiotensinogen to angiotensin I in the blood

d. Secretion of ACTH by the anterior pituitary

e. Secretion of angiotensin II by the kidney

c. Conversion of angiotensinogen to angiotensin I in the blood

Which correctly describes the composition of the glomerular filtrate?

a. It is identical to urine, but has a much smaller flow rate.

b. It is identical to urine, but has a much larger flow rate.

c. It is identical to blood plasma, except it lacks red blood cells.

d. It is similar to plasma, except it does not contain glucose.

e. It is similar to plasma, except it does not contain plasma proteins.

e. It is similar to plasma, except it does not contain plasma proteins.

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

e. The collecting duct

How does the renal countercurrent multiplier mechanism allow the creation of a concentrated urine?

a. It transports NaCl from the medullary interstitial fluid into the collecting duct, which directly increases the osmolarity of the urine.

b. It transports urea from the medullary interstitial fluid into the collecting duct, which directly increases the osmolarity of the urine.

c. By concentrating NaCl in the renal medullary interstitial fluid, 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 interstitial fluid and water follows, concentrating the urine.

c. By concentrating NaCl in the renal medullary interstitial fluid, it allows water to be reabsorbed from the collecting ducts when vasopressin is present.

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.

b. The filtered load of glucose becomes greater than the tubular maximum for its reabsorption.

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.

b. Primary active transport of Na⁺ allows for secondary active transport of glucose and H⁺ in the proximal tubule.

Which of the following statements regarding renal handling of Na⁺ is correct?

a. In the proximal tubule, Na⁺ is actively transported across the luminal membrane of the tubular epithelial cells.

b. Atrial natriuretic factor increases Na⁺ reabsorption.

c. In the absence of aldosterone, Na⁺ will be secreted by the cortical collecting ducts.

d. Na⁺ is actively reabsorbed in the ascending limb of the loop of Henle.

e. Without vasopressin, the collecting duct is impermeable to Na⁺.

d. Na⁺ is actively reabsorbed in the ascending limb of the loop of Henle.

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.

a. It is secreted by juxtaglomerular cells in renal afferent arterioles.

After prolonged exertion in a hot climate, baroreceptors would __________ firing, leading to __________ secretion of __________ and thus __________ renal reabsorption of __________.

a. increase; increased; renin; increased; Na⁺

b. decrease; increased; renin; decreased; Na⁺

c. decrease; increased; vasopressin; increased; water

d. increase; decreased; vasopressin; decreased; water

e. decrease; decreased; vasopressin; increased; water

c. decrease; increased; vasopressin; increased; water

Which of the following statements about renal control of blood acid-base balance is TRUE?

a. Increased metabolism of glutamine by renal tubular cells increases the plasma bicarbonate concentration.

b. Excretion in the urine of hydrogen bound to phosphate buffers decreases plasma bicarbonate concentration.

c. H⁺ that binds to filtered bicarbonate in the tubular fluid is excreted in the urine.

d. When hypoventilation occurs at the lungs, the kidneys compensate by reducing glutamine metabolism.

e. The kidneys compensate for a metabolic alkalosis by increasing CO₂ production.

a. Increased metabolism of glutamine by renal tubular cells increases the plasma bicarbonate concentration.