Chapter 26: Renal Function QUIZ

Hormones that increase sodium reabsorption from the tubular fluid include (Select all that apply.) a. aldosterone. b. atrial natriuretic peptide. c. antidiuretic hormone. d. urodilatin. e. angiotensin II.

a. aldosterone. e. angiotensin II. Aldosterone and angiotensin II result in sodium reabsorption. Atrial natriuretic peptide and urodilatin decrease sodium reabsorption. Antidiuretic hormone does not affect sodium reabsorption.

Factors that increase the glomerular filtration rate include a. fluid volume excess. b. increased hydrostatic pressure in the Bowman's capsule. c. high oncotic pressure in glomerular capillary blood. d. obstruction in the renal tubules.

a. fluid volume excess. Fluid volume excess increases blood volume which increases glomerular filtration. Increased hydrostatic pressure in the Bowman's capsule, high oncotic pressure in the glomerular capillary, and obstruction of renal tubules oppose filtration.

The primary selectivity barrier for glomerular filtration is the a. glomerular basement membrane. b. endothelial tight junctions. c. epithelial fenestra. d. mesangial cells.

a. glomerular basement membrane. The basement membrane is an important selectivity barrier of the glomerulus, preventing plasma proteins, RBCs, WBCs, and platelets from passing through the glomerulus.

Serious renal impairment generally does not occur until ____ of the total nephrons have been damaged a. 20% b. 40% c. 60% d. 80%

d. 80%

Which finding on urinalysis should prompt further evaluation? a. pH 4.5 b. Red blood cells 2 per high-power field c. Specific gravity of 1.015 d. White blood cells 20 per high-power field

d. White blood cells 20 per high-power field This many WBCs in the urine indicate urinary tract infection; 5 or more is not expected. 4.5 is a normal pH. Fewer than 5 RBCs is insignificant. 1.015 is a normal specific gravity.

The glucose transporter in the proximal tubule a. has no transport maximum. b. does not depend on sodium reabsorption. c. is ATP dependent. d. may be saturated at high filtered glucose loads.

d. may be saturated at high filtered glucose loads. The glucose transporter in the proximal tubule may be saturated at high filtered glucose loads; glycosuria then results

The glomerular filtration rate is most accurately reflected in the a. blood urea nitrogen level. b. urinary output. c. serum osmolality. d. serum creatinine level.

d. serum creatinine level. Serum creatinine is a fairly reliable indicator of glomerular filtration as it is stable. The blood urea nitrogen level, urinary output, and serum osmolality are affected by factors that make them less reliable as indicators of glomerular filtration.

Approximately two-thirds of the water and electrolytes filtered by the kidney are reabsorbed by the a. loop of Henle. b. collecting tubule. c. distal tubule. d. proximal tubule.

d. proximal tubule. Approximately two-thirds of the water and electrolytes filtered by the kidney are reabsorbed by the proximal tubule. Two-thirds of the water and electrolytes filtered by the kidney are not reabsorbed by the loop of Henle, collecting tubule, or distal tubule.

The blood urea nitrogen (BUN) level is affected by (Select all that apply.) a. protein intake. b. fat intake. c. fluid intake. d. catabolism. e. renal function.

a. protein intake. c. fluid intake. d. catabolism. e. renal function The blood urea nitrogen is affected by protein intake, fluid intake, rate of catabolism, and renal function. Urea is not an end product of fat intake, and the blood urea nitrogen level is unaffected by fat intake.

An important sign of glomerular basement membrane dysfunction is a. proteinuria. b. hematuria. c. glycosuria. d. urinary casts.

a. proteinuria. Proteinuria is an important sign of basement membrane dysfunction. Hematuria can be found in glomerular disorders but it is not specific to this; it can be caused by many disorders. Glycosuria is found primarily in diabetes mellitus. Urinary casts do not necessarily mean basement membrane dysfunction.

The underlying mechanism which directly results in glycosuria is a. filtration of glucose from the glomerulus. b. exceeding the threshold for glucose reabsorption. c. secretion of glucose into the distal tubule. d. the mechanism is unknown.

b. exceeding the threshold for glucose reabsorption. Glucose is normally freely filtered but then reabsorbed from the tubules into the peritubular capillaries. If the threshold for reabsorption is exceeded as in uncontrolled diabetes mellitus, glycosuria results. Glucose is freely filtered from the glomerulus; this is not the direct cause of glycosuria. Glucose is not secreted into the distal tubule. The underlying mechanism that directly results in glycosuria is exceeding the threshold for glucose reabsorption.

The main driving force for glomerular filtration is a. oncotic pressure in the Bowman's capsule. b. hydrostatic pressure in glomerular capillaries. c. permeability of the glomerular membrane. d. solute content of the blood in the glomerular capillaries.

b. hydrostatic pressure in glomerular capillaries. Hydrostatic pressure within the glomerular capillaries is the main driving force for filtration. A significant drop in blood pressure such as in shock severely reduces glomerular filtration. Oncotic pressure in the Bowman's capsule, permeability of the glomerular membrane, and solute content of the blood in the glomerular capillaries are not the main driving forces for filtration.

It is true that glucose reabsorption in the tubules a. occurs passively. b. occurs in the proximal convoluted tubule. c. is unlimited. d. simply does not occur.

b. occurs in the proximal convoluted tubule.

Renin is released from a. the posterior pituitary gland. b. the liver. c. juxtaglomerular cells. d. macula densa cells.

c. juxtaglomerular cells.

Serum creatinine may be increased by a. carbohydrate intake. b. fat intake. c. muscle breakdown. d. fluid intake.

c. muscle breakdown. Creatinine is an end product of muscle metabolism; muscle breakdown will increase the serum creatinine level. Serum creatinine is not affected by carbohydrate, fat, or fluid intake. Fluid volume deficit can increase the serum creatinine if it leads to acute renal failure.

The primary function of the vasa recta is to a. secrete renin. b. reabsorb NaCl. c. reabsorb interstitial fluid. d. secrete urea.

c. reabsorb interstitial fluid.

Excess potassium is excreted from the body by the renal system primarily via a. glomerular filtration based on blood level of potassium. b. reabsorption based on blood level of potassium. c. secretion based on aldosterone level. d. an unknown mechanism.

c. secretion based on aldosterone level. Potassium is secreted from the distal tubule and collecting ducts into the tubule lumen under the influence of aldosterone. Excess potassium is not excreted from the body by the renal system via glomerular filtration or the renal system based on the blood level of potassium, nor is it excreted from the body by the renal system based on the aldosterone level.