Explanation:

The correct path of filtrate through a nephron starts in the renal corpuscle, which is comprised of the glomerulus and Bowman"s capsule. Filtrate then passes through the proximal convoluted tubule, where the majority of reabsorption takes place. It then travels through the descending and ascending limbs of the Loop of Henle, creating the counter current multiplier gradient that will allow urine to be concentration in the collecting duct. From the Loop of Henle, filtrate enters the distal convoluted tubule for final reabsorption before entering the collecting duct and being trasported to the bladder.

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The renal artery is used to carry blood into the kidneys. Filtrate originates from the renal artery, but it is not a part of the nephrons.


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Example Question #472 : Biology


What is the main function of the Loop of Henle within each nephron?


Possible Answers:

The Loop of Henle is the site at which the hormone vasopressin takes its greatest effect


The Loop of Henle creates a countercurrent multiplier system


The Loop of Henle is the primary site of glucose and amino acid reabsorption


The Loop of Henle contains Bowman"s capsule, which is where filtrate first enters the nephron


Correct answer:

The Loop of Henle creates a countercurrent multiplier system


Explanation:

The Loop of Henle creates a countercurrent multiplier system. As the filtrate descends through the Loop of Henle, water leaves the filtrate and is reabsorbed, making the filtrate very concentrated. When the Loop of Henle ascends, salt ions leave the filtrate and are reabsorbed making the filtrate less concentrated. This creates a strong concentration of ions in the interstitial fluid toward the bottom of the loop, as compared to the concentration at the top. When filtrate flows down the collecting duct, this gradient helps concentrate the urine by removing water.


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Example Question #471 : Biology


A renal afferent arteriole has a larger radius than the efferent arteriole. What is the effect of this larger radius on the function of the kidney?


Possible Answers:

Afferent arteriole flow is decreased


Reabsorption in the nephron tubules is increased


Antidiuretic hormone (ADH) secretion is decreased


Glomerular filtration rate is decreased


Blood flow to the kidney is decreased


Correct answer:

Reabsorption in the nephron tubules is increased


Explanation:

A renal afferent arteriole is directed toward the glomerulus, while a renal efferent arteriole is directed away from the glomerlus. If the radius of the afferent arteriole is increased, there is more flow through it toward the glomerulus, and if there is a smaller radius in the efferent arteriole, there is a resultant back pressure in the glomerulus. This is can be imagined as trying to squeeze a high-pressure hose through a small pipe. This pressure increases the force within the glomerulus to increase filtration, and subsequently increase reabsorption.

Antidiuretic hormone (ADH) secretion has a neglible effect on the radius of renal arterioles. Blood flow to the kidney is increased when afferent arteriole radius is increased (this also increases the arteriole flow).


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Example Question #474 : Biology


At which point in a nephron would the osmolarity of the filtrate be highest? Assume that antidiuretic hormone (ADH) is not present in the body.


Possible Answers:

The distal convoluted tubule


The bottom of the loop of Henle


The proximal convoluted tubule


The collecting duct


Correct answer:

The bottom of the loop of Henle


Explanation:

It is important to understand how urine is concentrated as it travels through the nephron. The proximal convoluted tubule does not alter the osmolarity of the filtrate, the loop of Henle increases the osmolarity of the filtrate, and the distal convoluted tubule lowers the osmolarity of the filtrate. In the absence of antidiuretic hormone, the collecting duct will be impermeable to water, preventing it from leaving the filtrate and resulting in more dilute urine. With the collecting duct impermeable to water, the filtrate will be most concentrated at the bottom of the loop of Henle.


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Example Question #475 : Biology


The interaction between blood pressure and kidney function in humans requires coordination by the renin-angiotensin-aldosterone system (RAAS). This system involves the dynamic interplay of the kidneys, lungs, and blood vessels to carefully regulate sodium and water balance.

A normal human kidney has cells adjacent to the glomerulus called juxtaglomerular cells. These cells sense sodium content in urine of the distal convoluted tubule, releasing renin in response to a low level. Renin is an enzyme that converts angiotensinogen to angiotensin I (AI). AI is converted to angiotensin II (AII) by angiotensin converting enzyme (ACE) in the lung.

AII stimulates aldosterone secretion in the zona glomerulosa of the adrenal gland. Aldosterone then acts to upregulate the sodium-potassium pump on the basolateral side of distal tubule epithelial cells to increase sodium reabsorption from the urine, as well as increasing potassium excretion.


The passage notes that the RAAS functions at the distal tubule. What is the primary function of the proximal tubule?


Possible Answers:

Solute reabsorption and secretion


Transport of urine from the loop of Henle to the collecting duct


Filtration


Detoxification of filtrate


Concentration of filtrate


Correct answer:

Solute reabsorption and secretion


Explanation:

The proximal tubule is the primary site of solute reabsorption and secretion, modifying the urine after its initial filtration in the glomerulus.

Concentration of the filtrate primarily occurs in the collecting duct, and the distal convoluted tubule transports urine from the loop of Henle to the collecting duct. Filtration occurs in the glomerulus and Bowman"s capsule, know together as the renal corpuscle.


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Example Question #476 : Biology


The interaction between blood pressure and kidney function in humans requires coordination by the renin-angiotensin-aldosterone system (RAAS). This system involves the dynamic interplay of the kidneys, lungs, and blood vessels to carefully regulate sodium and water balance.

A normal human kidney has cells adjacent to the glomerulus called juxtaglomerular cells. These cells sense sodium content in urine of the distal convoluted tubule, releasing renin in response to a low level. Renin is an enzyme that converts angiotensinogen to angiotensin I (AI). AI is converted to angiotensin II (AII) by angiotensin converting enzyme (ACE) in the lung.

AII stimulates aldosterone secretion in the zona glomerulosa of the adrenal gland. Aldosterone then acts to upregulate the sodium-potassium pump on the basolateral side of distal tubule epithelial cells to increase sodium reabsorption from the urine, as well as increasing potassium excretion.


The first place that early urine is collected after filtration in the glomerulus is which of the following?


Possible Answers:

Distal tubule


Collecting duct


Loop of Henle


Bowman"s capsule


Proximal tubule


Correct answer:

Bowman"s capsule


Explanation:

Bowman"s capsule collects fluid filtered from the glomerulus and serves as a site of entry into the proximal tubule. The glomerulus is a convoluted capillary bed adjacent to Bowman"s capsule. Osmotic and oncotic pressure gradients work to filter the blood from the glomerulus into Bowman"s capsule. The nature of the epithelial cells that line the glomerulus determines the permeability of the filtration, and prevents unwanted content in the urine.

Filtrate moves from Bowman"s capsule to the proximal tubule and into the loop of Henle, which dives into the renal medulla before returning to the renal cortex. From the loop of Henle, filtrate is transferred to the distal tubule and into the collecting duct, where it travels into the renal medulla for collection.


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Example Question #477 : Biology


The interaction between blood pressure and kidney function in humans requires coordination by the renin-angiotensin-aldosterone system (RAAS). This system involves the dynamic interplay of the kidneys, lungs, and blood vessels to carefully regulate sodium and water balance.

A normal human kidney has cells adjacent to the glomerulus called juxtaglomerular cells. These cells sense sodium content in urine of the distal convoluted tubule, releasing renin in response to a low level. Renin is an enzyme that converts angiotensinogen to angiotensin I (AI). AI is converted to angiotensin II (AII) by angiotensin converting enzyme (ACE) in the lung.

AII stimulates aldosterone secretion in the zona glomerulosa of the adrenal gland. Aldosterone then acts to upregulate the sodium-potassium pump on the basolateral side of distal tubule epithelial cells to increase sodium reabsorption from the urine, as well as increasing potassium excretion.


A nephrologist is studying a normal glomerulus, and notes that it is actively filtering blood normally. What type of blood vessels comprise the bulk of the glomerulus?


Possible Answers:

Arterioles


Fenestrated capillaries


Arteries


Unfenestrated capillaries


Venules


Correct answer:

Fenestrated capillaries


Explanation:

The main purpose of the glomerulus is filtration; thus, it is mainly composed of the thinnest walled-blood vessels (capillaries), and specifically those with pores (fenestrations) to facilitate filtration.


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Example Question #478 : Biology


The interaction between blood pressure and kidney function in humans requires coordination by the renin-angiotensin-aldosterone system (RAAS). This system involves the dynamic interplay of the kidneys, lungs, and blood vessels to carefully regulate sodium and water balance.

A normal human kidney has cells adjacent to the glomerulus called juxtaglomerular cells. These cells sense sodium content in urine of the distal convoluted tubule, releasing renin in response to a low level. Renin is an enzyme that converts angiotensinogen to angiotensin I (AI). AI is converted to angiotensin II (AII) by angiotensin converting enzyme (ACE) in the lung.

AII stimulates aldosterone secretion in the zona glomerulosa of the adrenal gland. Aldosterone then acts to upregulate the sodium-potassium pump on the basolateral side of distal tubule epithelial cells to increase sodium reabsorption from the urine, as well as increasing potassium excretion.


Aldosterone functions by increasing the rate at which the sodium-potassium pump functions in the basolateral surface of distal tubule epithelial cells of the nephron. Which of the following is true of the sodium-potassium pump?


Possible Answers:

It pumps two sodium ions out of the cytosol and three potassium ions into the cytosol


It pumps two sodium ions into the cytosol and three potassium ions out of the cytosol


It pumps three sodium ions into the cytosol and two potassium ions out of the cytosol


It pumps three sodium ions into the cytosol and three potassium ions out of the cytosol


It is electrogenic


Correct answer:

It is electrogenic


Explanation:

The sodium-potassium pump pumps three sodium ions out of the cytosol, and two potassium ions into the cytosol. It is electrogenic because each sodium and potassium ion have a charge of positive one, and the two ions are pumped in unequal quantities. The pump generates an electric gradient and current due to the directional flow of positive charge out of the cell.

When aldosterone is released, it increases the action of the sodium-potassium pump, causing excess sodium to be removed from the filtrate in the distal tubule, thus conserving sodium and drawing water out of the filtrate.


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Example Question #479 : Biology


Hypersensitivity reactions occur when body tissues are affected by an abnormal immune reaction. The result is damage to normal tissues and clinical illness. A peanut allergy is an example of a hypersensitivity reaction, but there are three additional broad classes.

One class involves the abnormal production or deposition of antibodies. Antibodies are B-cell derived molecules that normally adhere to pathogens, rendering them unable to continue an infection. When antibodies are produced against normal tissues, however, disease can result. Figure 1 depicts a schematic structure of an antibody.

Antibodies can be divided into two peptide chains: heavy and light. Heavy chains form the backbone of the antibody, and are attached to light chains via covalent bonding. Each heavy and light chain is then further divided into constant and variable regions. Variable regions exhibit molecular variety, generating a unique chemical identity for each antibody. These unique patterns help guarantee that the body can produce antibodies to recognize many possible molecular patterns on invading pathogens.

 

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In hypersensitivity reactions, antibodies can complex with antigens and fall out of solution from the blood. These immune complexes then deposit in body tissues inappropriately, and cause disease. This situation is especially noticeable in body tissues that have a direct filtering function. Which of the following structures would most likely be affected by a disease caused by immune complex deposition?


Possible Answers:

Sinoatrial node


Explanation:

The glomerulus is the primary site of filtration in the kidney. Together, the glomerulus and Bowman"s capsule for the renal corpuscle of the nephron and are responsible for collecting filtrate from the blood. Deposition and accumulation of immune complexes in the glomerulus would result in blockage of its filtering functions, impeding nephron function and preventing proper excretion of soluble wastes.

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The sinoatrial node is the natural pacemaker region of the heart, located in the right atrium. Haversian canals are the central regions of osteons and often house nerves and blood vessels, facilitating cellular communication within bone. Neuromuscular junctions are the interface regions between a single neuron and the muscle fiber it innervates. The semicircular canals are located in the inner ear and function in the propagation an integration of sound vibrations. None of these structures are involved in filtration, and they would most likely be unaffected by the presence of immune complexes in the body.