Human Anatomy and Physiology : Help with Nephron Physiology

Study concepts, example questions & explanations for Human Anatomy and Physiology

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Example Questions

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Example Question #1 : Help With Nephron Physiology

Which of the following nephron sections is primarily associated with the absorption of sodium ions and the secretion of potassium ions?

Possible Answers:

Proximal convoluted tubule

Distal convoluted tubule

Glomerulus

Loop of Henle

Correct answer:

Distal convoluted tubule

Explanation:

The distal convoluted tubule follows the loop of Henle in the nephron structure. In addition to lowering the filtrate concentration, it is also used to reabsorb sodium ions and secrete potassium ions. Aldosterone acts on the distal tubule and further stimulates these two actions.

Example Question #2 : Help With Nephron Physiology

Which section of the nephron does not result in a change in filtrate concentration?

Possible Answers:

Loop of Henle

Collecting duct

Distal convoluted tubule

Proximal convoluted tubule

Correct answer:

Proximal convoluted tubule

Explanation:

The nephron is composed of multiple sections, which are used to alter the solute composition and concentration of the filtrate. The first section is the proximal convoluted tubule. While the solute composition of the filtrate will change due to reabsorption and secretion of specific solutes, the overall concentration does not change. In the proximal convoluted tubule, filtrate is kept isotonic with blood.

Example Question #3 : Help With Nephron Physiology

How does antidiuretic hormone (ADH) affect the nephron?

Possible Answers:

ADH makes the collecting duct permeable to water, concentrating the urine

ADH makes the collecting duct permeable to water, diluting the urine

ADH makes the loop of Henle permeable to water, concentrating the urine

ADH makes the collecting duct impermeable to water, concentrating the urine

ADH makes the loop of Henle impermeable to water, concentrating the urine

Correct answer:

ADH makes the collecting duct permeable to water, concentrating the urine

Explanation:

The collecting duct of a nephron is normally impermeable to water. In the presence of antidiuretic hormone (ADH), aquaporin proteins are inserted, making the collecting duct permeable to water. Water then diffuses into the medulla due to the solute concentration of the surrounding tissues, generated from ion reabsorption in the loop of Henle. This loss of water from the urine makes it more concentrated.

Example Question #4 : Help With Nephron Physiology

The glomerulus is primarily associated with which function?

Possible Answers:

Filtration

Active transport

Protein reabsorption

Ion reabsorption

Secretion

Correct answer:

Filtration

Explanation:

The glomerulus is a capillary structure associated with the first section of the nephron where blood enters the renal corpuscle. The glomerulus is responsible for filtering fluid, plasma, and dissolved particulates out of circulation and into Bowman's capsule, resulting in a primary filtrate that will go through the rest of the nephron.

Example Question #5 : Help With Nephron Physiology

Which of the following is true regarding the nephron?

Possible Answers:

Water is reabsorbed in the distal convoluted tubule

All of these

The macula densa cells are found within the lumen of the distal convoluted tubule

Water is reabsorbed in the descending limb of the loop of Henle

Correct answer:

All of these

Explanation:

All of the answer choices are true. The macula densa cells are sensitive to changes in concentration of sodium chloride. A decrease in concentration of  is detected, which stimulates the macula densa cells to secrete paracrine factors that ultimately increase the pressure in the glomerulus, and thus the glomerular filtration rate, and stimulates the release of renin, which ultimately increases blood pressure, volume and cardiac output.

Example Question #6 : Help With Nephron Physiology

The major reabsorption of water, ions, and other important molecules such as glucose occurs in what part of the nephron?

Possible Answers:

Glomerulus

Distal convoluted tubule

Collecting duct

Proximal convoluted tubule

Vasa recta

Correct answer:

Proximal convoluted tubule

Explanation:

After filtration of the blood through the glomerulus, approximately 70% of the water and salts is reabsorbed in the proximal convoluted tubule.  Additionally, 100% of the glucose is reabsorbed here in a healthy, functioning nephron.  The lumenal cells of the proximal convoluted tubule are lined with microvilli and are called brush border cells.  Histology of the proximal convoluted tubule is indicative of these structures and the proximal convoluted tubule's lumen can be seen as "crowded" with epithelial surface area, which is distinct from the lumen of the distal convoluted tubule.

Example Question #7 : Help With Nephron Physiology

ADH (antidiuretic hormone, also known as vasopressin) has which of the following effects on nephron function?

Possible Answers:

Reabsorption of water decreases as a result of less aquaporins being placed in the proximal convoluted tubule

Reabsorption of water decreases as a result of additional aquaporins being placed in the distal convoluted tubule and collecting duct

Reabsorption of water increases as a result of additional aquaporins being placed in the distal convoluted tubules and collecting duct

Reabsorption of water increases as a result of more ATP-dependent water pumps in the distal convoluted tubule and collecting duct

Reabsorption of water increases as a result of additional aquaporins being placed in the proximal convoluted tubule

Correct answer:

Reabsorption of water increases as a result of additional aquaporins being placed in the distal convoluted tubules and collecting duct

Explanation:

ADH acts upon the collecting ducts and distal convoluted tubules of nephrons to increase water reabsorption.  It causes an increase in the number of aquaporins in order to allow for this.

Example Question #8 : Help With Nephron Physiology

If the afferent arteriole becomes constricted, what is likely to occur in the nephron?

Possible Answers:

Glomerular filtration rate will remain the same

The increased osmotic pressure will elevate glomerular filtration rate

Fluid backup will cause the nephron to rupture

The increased hydrostatic pressure will elevate glomerular filtration rate

Glomerular filtration rate will decrease due to a loss in blood pressure

Correct answer:

The increased hydrostatic pressure will elevate glomerular filtration rate

Explanation:

The afferent arteriole carries blood away from the glomerulus, and so if it is constricted, the blood pressure behind it will increase.  The raise in blood pressure will result in an increase in hydrostatic pressure, pushing additional fluid through the glomerulus i.e elevated glomerular filtration rate. While high hydrostatic pressure does cause damage to the nephron, the nephron rupturing is too extreme of a statement and requires assumptions that are not necessarily valid.

Example Question #9 : Help With Nephron Physiology

Concentration and dilution of urine is a major responsibility of what part of the nephron?

Possible Answers:

Loop of Henle

Proximal convoluted tubule

Collecting duct

Distal convoluted tubule

Glomerulus

Correct answer:

Loop of Henle

Explanation:

As filtrate passes through the Loop of Henle, the level of concentration of the fluid that will become urine is determined by the length of the loop of Henle (how far into the medulla it dips) and, the osmolality of the medulla. Depending on the levels of circulating hormones, the distal convoluted tubule and collecting duct could be the part of the nephron that determines the concentration of the urine, but to a lesser extent than the length of the loop of Henle. 

Example Question #10 : Help With Nephron Physiology

The descending limb of the loop of Henle is __________.

Possible Answers:

water permeable and solute impermeable

water permeable

solute permeable

water and solute impermeable

solute impermeable

Correct answer:

water permeable and solute impermeable

Explanation:

The descending limb of the loop of Henle is both water permeable and solute impermeable.  These properties of the limb allow the filtrate moving through the nephron to become either concentrated or diluted depending on the circumstance.

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