Question 1

Which is the critical feature that enables the mammalian kidney to concentrate urine?

Accepted Answer

Nephrons with long loops of Henle are the critical feature that enables the mammalian kidney to concentrate urine. This is because the longer the loop of Henle, the more time the filtrate spends in contact with the hypertonic interstitial fluid in the renal medulla, allowing for greater reabsorption of water and concentration of urine.

Question 2

In humans, about _______ percent of the fluid volume filtered out of the glomerulus is returned to the blood via reabsorption.

Accepted Answer

Approximately 99% of the fluid volume filtered out of the glomerulus is returned to the blood via reabsorption in the nephron, highlighting the kidney's efficiency in conserving water and essential solutes.

Question 3

Which event happens in the collecting ducts of the mammalian kidney?

Accepted Answer

In the collecting ducts, water moves out via osmosis and urea diffuses out. This process is important for concentrating urine and conserving water in the body. The other options listed (B, C, D, and E) do not accurately describe the primary process that occurs in the collecting ducts.

Question 4

Which feature does not characterize the thin descending limb of the loop of Henle?

Accepted Answer

The thin descending limb of the loop of Henle is surrounded by interstitial fluid of increasing osmolarity, not lower osmolarity, as it descends deeper into the medulla. This gradient is crucial for the osmosis of water out of the limb, concentrating the urine.

Question 5

Which statement about the renal filtrate is false?

Accepted Answer

Excreted urine is not very similar in composition to the original glomerular filtrate. There are a number of substances that are reabsorbed, secreted, or modified within the nephron before urine is excreted. Some of the key substances that are reabsorbed include water, glucose, amino acids, sodium, potassium, and bicarbonate. Some of the key substances that are secreted include hydrogen ions, potassium, and certain drugs and toxins. By the time urine is excreted, it is quite different in composition from the original filtrate.

Question 6

Choose the correct path by which urine moves from its site of production to where it exits the body.

Accepted Answer

Urine is produced in the kidneys, then it flows through the ureters to the urinary bladder, where it is stored until it exits the body through the urethra.

Question 7

Which statement about the thick ascending limb of the loop of Henle is false?

Accepted Answer

The actions of the thick ascending limb actually produce a higher osmolarity of the interstitial fluid, not a lower osmolarity. This is because the thick ascending limb actively transports ions (such as Na+, K+, and Cl-) out of the filtrate, creating a concentration gradient that draws water out of the descending limb and into the interstitial fluid. This process is known as the countercurrent multiplier mechanism and allows for the production of a concentrated urine.

Question 8

Choose the correct path by which filtrate moves, beginning with where it enters a nephron.

Accepted Answer

The correct path of filtrate movement through a nephron starts from the Bowman's capsule, then moves to the proximal convoluted tubule, followed by the loop of Henle, the distal convoluted tubule, the collecting duct, and finally to the renal pelvis.

Question 9

Like the thick ascending limb of the loop of Henle, the thin ascending limb is

Accepted Answer

The thin ascending limb of the loop of Henle is impermeable to water, which allows for the concentration of urine as it ascends through this segment.

Question 10

Which feature does not characterize the proximal convoluted tubule?

Accepted Answer

The statement "Because of its activities, fluid entering the loop of Henle has the same osmolarity and composition as blood plasma" is not a characteristic of the proximal convoluted tubule. The correct statement is that the proximal convoluted tubule is responsible for most of the reabsorption of water and solutes from the filtrate, has cells with numerous microvilli on their apical surfaces, indicating it is a site for reabsorption, performs isosmotic reabsorption, and has cells with numerous mitochondria, indicating they are metabolically very active.

Question 11

Refer to the figure showing the glomerular filter.  Based on the figure, which statement is false?

Accepted Answer

The answer of Refer to the figure showing the glomerular...

Question 12

Which feature does not characterize aquaporins?

Accepted Answer

Aquaporins are not prevalent in cells of the ascending limb of the loop of Henle because this segment is impermeable to water, focusing instead on the reabsorption of ions.

Question 13

Which component(s) is/are responsible for the solute concentration gradient in the interstitial fluid of the medulla?

Accepted Answer

NaCl and urea are responsible for creating the high osmolarity of the interstitial fluid in the medulla, which drives water reabsorption from the collecting ducts in the nephron.

Question 14

Which statement about renal filtration is false?

Accepted Answer

Glucose, amino acids, and excess ions are actually actively reabsorbed from the filtrate into the blood, not secreted into the renal tubule. The other statements are true: the composition of filtrate is similar to that of blood plasma but lacks proteins, substances can be secreted from blood to filtrate during secretion, and reabsorption involves movement of substances from filtrate to blood. Additionally, filtrate from individual nephrons enters collecting ducts, as stated, but this statement is not false.

Question 15

Which statement about the collecting ducts of nephrons is false?

Accepted Answer

The answer of Which statement about the collecting ducts of...

Question 16

Which regions of the nephron fine-tune the ionic composition of urine?

Accepted Answer

The distal convoluted tubule and collecting duct are responsible for fine-tuning the ionic composition of urine by regulating the secretion and reabsorption of ions such as sodium, potassium, and hydrogen. The proximal convoluted tubule and loop of Henle play a role in regulating overall solute concentration, but do not fine-tune specific ion composition. The Bowman's capsule is responsible for filtrating blood, but does not play a role in regulating ion composition.

Question 17

Which feature does not characterize the vasa recta?

Accepted Answer

The vasa recta is characterized by all of the other options listed. However, it is not impermeable to salt, as it plays a crucial role in maintaining the concentration gradient in the renal medulla by filtering and reabsorbing salt ions.

Question 18

Cells of the _______ are like those in the proximal convoluted tubule in being specialized for transport.These cells actively transport _______ and Cl^- from the filtrate to the interstitial fluid.

Accepted Answer

The thick ascending limb of the loop of Henle contains cells that are specialized for transport and actively transport Na+, K+, and Cl- from the filtrate into the interstitial fluid.

Question 19

Choose the incorrect pairing between structure of a nephron and location within a kidney.

Accepted Answer

The distal convoluted tubule is located in the cortex of the kidney, not the medulla.

Question 20

The internal core of the kidney is the _______, the outer layer is the _______, and _______ are in both.

Accepted Answer

The answer of The internal core of the kidney is...

Quiz 51: Salt and Water Balance and Nitrogen Excretion

Which is the critical feature that enables the mammalian kidney to concentrate urine?

In humans, about _______ percent of the fluid volume filtered out of the glomerulus is returned to the blood via reabsorption.

Which event happens in the collecting ducts of the mammalian kidney?

Which feature does not characterize the thin descending limb of the loop of Henle?

Which statement about the renal filtrate is false?

Choose the correct path by which urine moves from its site of production to where it exits the body.

Which statement about the thick ascending limb of the loop of Henle is false?

Choose the correct path by which filtrate moves, beginning with where it enters a nephron.

Like the thick ascending limb of the loop of Henle, the thin ascending limb is

Which feature does not characterize the proximal convoluted tubule?

Refer to the figure showing the glomerular filter. Based on the figure, which statement is false?

Which feature does not characterize aquaporins?

Which component(s) is/are responsible for the solute concentration gradient in the interstitial fluid of the medulla?

Which statement about renal filtration is false?

Which statement about the collecting ducts of nephrons is false?

Which regions of the nephron fine-tune the ionic composition of urine?

Which feature does not characterize the vasa recta?

Cells of the _ are like those in the proximal convoluted tubule in being specialized for transport.These cells actively transport _ and Cl^- from the filtrate to the interstitial fluid.

Choose the incorrect pairing between structure of a nephron and location within a kidney.

The internal core of the kidney is the ___, the outer layer is the _, and _____ are in both.

Quiz 51: Salt and Water Balance and Nitrogen Excretion

Which is the critical feature that enables the mammalian kidney to concentrate urine?

In humans, about _______ percent of the fluid volume filtered out of the glomerulus is returned to the blood via reabsorption.

Which event happens in the collecting ducts of the mammalian kidney?

Which feature does not characterize the thin descending limb of the loop of Henle?

Which statement about the renal filtrate is false?

Choose the correct path by which urine moves from its site of production to where it exits the body.

Which statement about the thick ascending limb of the loop of Henle is false?

Choose the correct path by which filtrate moves, beginning with where it enters a nephron.

Like the thick ascending limb of the loop of Henle, the thin ascending limb is

Which feature does not characterize the proximal convoluted tubule?

Refer to the figure showing the glomerular filter. Based on the figure, which statement is false?

Which feature does not characterize aquaporins?

Which component(s) is/are responsible for the solute concentration gradient in the interstitial fluid of the medulla?

Which statement about renal filtration is false?

Which statement about the collecting ducts of nephrons is false?

Which regions of the nephron fine-tune the ionic composition of urine?

Which feature does not characterize the vasa recta?

Cells of the _______ are like those in the proximal convoluted tubule in being specialized for transport.These cells actively transport _______ and Cl- from the filtrate to the interstitial fluid.

Choose the incorrect pairing between structure of a nephron and location within a kidney.

The internal core of the kidney is the _______, the outer layer is the _______, and _______ are in both.

Cells of the _ are like those in the proximal convoluted tubule in being specialized for transport.These cells actively transport _ and Cl^- from the filtrate to the interstitial fluid.

The internal core of the kidney is the ___, the outer layer is the _, and _____ are in both.