Human Physiology - Problem Drill 17: The Kidneys and Nephronal Physiology Question No. 1 of 10 Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems on paper as 1. This structure surrounds the glomerular capillary and captures the filtrate. Question #01 (A) Distal tubule. (B) Afferent arteriole. (C) Bowman s capsule. (D) Proximal tubule. (E) Loop of Henle. Bowman s capsule is the structure which surrounds the glomerular capillary. The afferent arteriole is the vessel which leads into the glomerular capillary. The afferent arteriole does not capture the filtrate. C. Correct! Bowman s capsule is the membrane structure which surrounds the glomerular capillary and captures the filtrate. The proximal tubule does not surround the glomerulus. The Loop of Henle joins the proximal and distal tubules. It does not surround the glomerular capillary. Remember Bowman s capsule is the structure which surrounds the glomerular capillary and captures the fluid filtered from the glomerulus. Fluid then travels from Bowman s capsule to the proximal tubule of the nephron. The correct answer is (C).
Question No. 2 of 10 Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems on paper as 2. Which of the following processes results in substances moving from the tubule into the blood? Question #02 (A) Filtration (B) Secretion (C) Excretion (D) Elimination (E) Reabsorption Filtration occurs in the glomerulus where substances are filtered from the blood into the nephron. Secretion involves moving substances from the blood into the tubule. Excretion is the process of eliminating urine from the body. Elimination is the removal of urine from the body. E. Correct! Reabsorption is the process by which important substances are removed from the tubule and returned to circulation. Remember that reabsorption occurs for approximately 99% of what is filtered. The kidneys filter 180 L/day, whereas urine output is only 1-2 L/day. The process of reabsorption moves substances from the tubule into the blood, so that they do not appear in the urine. The correct answer is (E).
Question No. 3 of 10 Instructions: (1) Read the problem and answer choices carefully, (2) Work the problems on paper as 3. Which hormone inserts water pores into the collecting duct to reduce urine volume? Question #03 (A) anti-diuretic hormone (ADH) (B) aldosterone (C) atrial natriuretic hormone (D) estrogen (E) cortisol A. Correct! Anti-diuretic hormone reduces urine volume by inserting water channels in the collecting ducts, leading to an increase in water reabsorption. Aldosterone does not insert water channels in the collecting ducts. Answer Atrial natiuretic hormone decreased water reabsorption and increases urine volume. Estrogen does not alter renal functioning. Cortisol does not alter renal functioning. Anti-diuretic hormone (ADH), as the name implies, reduces urine output. ADH does this by inserting water channels into the collecting duct, which is normally impermeable to water. The presence of the water channels allows water to leave the collecting duct and be reabsorbed, thus reducing water content in the urine. The correct answer is (A).
Question No. 4 of 10 4. Which of the following substance should not appear in urine? Question #04 (A) Sodium (B) Water (C) Blood cells (D) Potassium (E) Hydrogen ions Not all sodium that is filtered is reabsorbed, so some sodium always appears in the urine. Over 90% of urine is water. C. Correct! Blood cells are too large to pass through the glomerular filter, so they do not appear in urine. Potassium is filtered at the glomerulus, but not all potassium is reabsorbed, so potassium appears in the urine. Hydrogen ions appear in the urine, often as a means of decreasing acidity of the blood. Remember to appear in the urine, a substance must first pass through the glomerular capillary into the nephron. Blood cells and proteins are too large to pass through the glomerular filter, so they should not appear in the urine. The correct answer is (C).
Question No. 5 of 10 5. Which of the following is not a test of kidney function? Question #05 (A) Plasma clearance test. (B) Blood urea nitrogen levels. (C) Glomerular filtration rate. (D) Urinalysis (E) All of the above are kidney function tests. Plasma clearance test do assess kidney function by determining how quickly substances are removed or cleared from the urine. Blood urea nitrogen (BUN) levels are measured to determine how well the kidneys are removing the waste product urea from the blood. Glomerular filtration rate is a test used to determine how well the blood is being filtered. Urinalysis is a commonly performed test in which urine is examined for the following contents: ph level, blood cell, immune cells, electrolyte levels, and glucose. E. Correct! Selections A-D all tests of kidney function. Remember the kidney function can be examined in a number of ways. Plasma clearance and blood urea nitrogen levels tests examine the kidney s ability to remove substances from the plasma. Glomerular filtration rate tests assess how quickly the blood is filtered, and urinalysis examines a number of factors in urine. The correct answer is (E).
Question No. 6 of 10 Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems on paper as 6. Which segment of the nephron completes the most reabsorption? Question #06 (A) Collecting duct. (B) Distal tubule. (C) Descending limb of the Loop of Henle. (D) Proximal tubule. (E) Ascending limb of the Loop of Henle. Collecting ducts do very little reabsorption except for when ADH is present, and then water is reabsorbed. The distal tubule completes very little reabsorption except for when the hormones ADH and aldosterone are present. The descending limb of the Loop of Henle reabsorbs some water, but not the majority of substances. D. Correct! The proximal tubule is the primary segment for reabsorption. The ascending limb of the Loop of Henle completes only a small amount of reabsorption. It is the first segment of the nephron, the proximal tubule, which completes the majority of reabsorption. Sixty-five to seventy percent of the sodium and water are reabsorbed, 100% of the glucose, and approximately 100% of amino acids are reabsorbed by this segment. A large portion of electrolytes and minerals are also reabsorbed here. The correct answer is (D).
Question No. 7 of 10 7. What happens when tubular maximum for glucose is exceeded? Question #07 (A) The kidneys stop functioning. (B) Glucose appears in the urine. (C) No sign is present when glucose levels exceed the tubular maximum. (D) Filtration of glucose is prohibited. (E) All glucose is cleared from plasma. The kidneys will continue to function, although more glucose is filtered and appears in the urine. B. Correct! When tubular maximum is exceeded, all the glucose cannot be reabsorbed and glucose appears in the urine. A sign for glucose exceeding the tubular maximum is the presence of glucose in the urine. Because blood glucose is elevated, more, not less, glucose is filtered. This results in the tubular maximum being exceeded. Glucose levels exceeding the tubular maximum are indicative of elevated plasma glucose levels. All glucose is therefore not cleared from the plasma. Tubular maximum refers to the maximum level at which the nephron can transport a substance. In this case, tubular maximum refers to the level of glucose that can be reabsorbed by the proximal tubule. If tubular maximum is exceeded, not all of the glucose can be reabsorbed as normal, and glucose appears in the urine. The correct answer is (B).
Question No. 8 of 10 8. Which structures transport urine from the kidney to the bladder? Question #08 (A) ureters (B) urethra (C) calyx (D) nephron (E) renal pyramid A. Correct! The ureters are hollow muscular tubes which transport urine from the kidney to the bladder. The urethra is a tube leading from the bladder to the external surface of the body. The calyx gathers fluid from the collecting duct and then drains into the renal pelvis. The nephron is the site of urine formation, not transport to the bladder. The renal pyramids contain nephrons and do not transport fluid from the kidney. Remember that a ureter leads from each kidney to the bladder. These tube-like structures transport fluid from the kidney for storage in the bladder. The correct answer is (A).
Question No. 9 of 10 9. What process is micturition? Question #09 (A) Filtration at the nephron. (B) Movement of substance from the blood to the nephron. (C) Storage of urine in the bladder. (D) Elimination of urine from the body. (E) Movement of substance from the nephron to the blood. Micturition is the elimination of urine from the body. Movement of a substance from the blood to the nephron is secretion, not the micturition reflex. Micturition is the elimination of urine from the body. D. Correct! Micturition is the elimination of urine from the body. Movement of a substance from the nephron to the blood is reabsorption, not micturition. Micturition is the reflex regulating urine elimination from the body. This reflex controls the sensory receptors in the bladder and regulation of the internal sphincter of the bladder. The correct answer is (D).
Question No. 10 of 10 10. What percentage of filtrate is reabsorbed? Question #10 (A) Less than 1 percent. (B) 10-15 percent. (C) 50 percent. (D) Approximately 70%. (E) At least 99%. Approximately 99% of the filtrate is reabsorbed by the nephron. Approximately 99% of the filtrate is reabsorbed by the nephron. Approximately 99% of the filtrate is reabsorbed by the nephron. Approximately 99% of the filtrate is reabsorbed by the nephron. E. Correct! Approximately 99% of the filtrate is reabsorbed by the nephron. A large volume of fluid is filtered by the glomeruli every day, almost 180 L/day. Only 1-2 L of this fluid becomes urine, therefore almost 99% of what is filtered is reabsorbed by the nephron. The correct answer is (E).