MAP 7 - Urinary System
Part D If the osmotic pressure in the glomerular capillaries increased from 28 mm Hg to 35 mm Hg, would net filtration increase or decrease?
net filtration would decrease (Yes, because osmotic pressure opposes filtration, increasing osmotic pressure would decrease net filtration.)
Part B You've counseled Mr. Boulard about how to prevent recurrence of his hypokalemia. Which of the statements he makes indicates a need for further instruction?
"There's lots of potassium in regular table salt, so I'll just use more." (Table salt is NaCl, not KCl. So ingesting it will not help prevent hypokalemia.)
diabetes mellitus
A group of diseases that result in too much sugar in the blood (high blood glucose).
diabetes ketoacidosis
A serious diabetes complication where the body produces excess blood acids (ketones).
Fetal kidneys have the primary responsibility of clearing wastes from the fetal blood.
False
Glomerular filtration is an ATP-driven process.
False
If the GFR is too low, needed substances may pass so quickly through the renal tubules that they are not absorbed and instead are lost in the urine.
False
Max needs to drink more water before exercise to avoid dehydration.
False (Max's urinalysis data indicate that his urine is already dilute (pale yellow with low specific gravity). If he drinks more water, the kidneys will simply eliminate it, further diluting the urine and possibly causing him to stop to urinate during the race.)
Part B Which of the following materials is NOT reabsorbed in the nephron loop?
Glucose (Virtually all of the glucose in the filtrate is reabsorbed in the proximal convoluted tubule before reaching the nephron loop.)
Given the correlation between urine color and urine concentration, which of the following statements is true about Max's urine?
Max's urine is most dilute before exercise. (The pale yellow urine and low specific gravity before exercise indicate that the kidneys are producing larger quantities of dilute urine.)
What would happen if the capsular hydrostatic pressure were increased above normal?
Net filtration would decrease.
If one says that the clearance value of glucose is zero, what does this mean?
Normally all the glucose is reabsorbed.
The mechanism of water reabsorption by the renal tubules is ________.
Osmosis
Ellen, a 47-year-old woman who has suffered kidney disease for several years, has been diagnosed with proteinuria. Her legs and feet are so swollen that she has difficulty walking. Her hands and her left arm are also swollen. What is proteinuria, and could this condition be playing a role in her swollen limbs?
Proteinuria is a condition in which large amounts of plasma proteins pass into the glomerular filtrate and are excreted in the urine, decreasing the colloid osmotic pressure. This causes more fluid to leave the blood into the tissues in the body, resulting in edema.
The lab results of a newly admitted patient indicate renal impairment. How might this affect the dosing regimen of drugs that are excreted by the kidney?
The dosage or the dosage interval may need to be reduced. (If the renal clearance of the drug is reduced by kidney disease, then drugs eliminated by the kidney may need to be given less often, in smaller amounts, or both. This appropriate regimen is often found in information provided by the drug manufacturer.)
Chapter 25 NCLEX-Style End of Chapter Clinical Case Study Questions Part A Mr. Boulard's blood pressure is quite high. How would this affect his nephron function? Choose the statement below that is most accurate.
The heart releases atrial natriuretic peptide that reduces sodium reabsorption at the kidney when blood pressure increases. (Atrial natriuretic peptide is released by the heart in response to high blood pressure. It targets the nephron where it reduces the reabsorption of sodium, which leads to less water being reabsorbed. More water is lost in urine, reducing the blood volume and blood pressure.)
Select the correct statement about the ureters.
The ureters are capable of peristalsis like that of the gastrointestinal tract.
Under normal conditions, the large renal arteries deliver one-fourth of the total cardiac output (about 1200 ml) to the kidneys each minute.
True
Water reabsorption through the proximal convoluted tubule is termed obligatory water reabsorption, whereas water reabsorption through the distal convoluted tubule is termed facultative water reabsorption.
True
Part C The reabsorption of sodium in the DCT is regulated primarily by __________.
aldosterone and ANP (Aldosterone increases Na+ reabsorption, and atrial natriuretic peptide (ANP) inhibits Na+Na+ reabsorption)
Art-labeling Activity: Figure 25.10a Drag the appropriate labels to their respective targets.
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Art-labeling Activity: Figure 25.10c Drag the appropriate labels to their respective targets.
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Art-labeling Activity: Figure 25.20b Drag the appropriate labels to their respective targets.
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Art-labeling Activity: Figure 25.3b Drag the appropriate labels to their respective targets.
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Art-labeling Activity: Figure 25.4b
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Art-labeling Activity: Figure 25.7a (1 of 2) Drag the appropriate labels to their respective targets.
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Art-labeling Activity: Figure 25.7a (2 of 2) Drag the appropriate labels to their respective targets.
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Art-labeling Activity: Figure 25.8 Drag the appropriate labels to their respective targets.
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Career Connections Video: The Urinary System Part A The rate of kidney filtrate formation would normally be dependent upon all of the following factors except __________.
blood calcium level
IP: Glomerular Filtration Part A Which of the following substances is not normally found in filtrate?
blood cells and large particles (Yes, both blood cells and large particles, such as proteins, are not allowed to filter through a healthy glomerular membrane.)
Part E Filtrate in a typical healthy nephron will include little if any __________.
blood cells and proteins (Proteins and blood cells are typically too large to pass through the filtration membrane between the blood and the glomerular capsule.)
Part D How are nutrient molecules such as glucose and amino acids reabsorbed through the apical surfaces of the tubule epithelia?
by secondary active transport (Glucose is reabsorbed via symport carrier proteins via secondary active transport with Na+.)
Chemicals that enhance urinary output are called __________.
diuretics
Your patient's urinalysis shows a large amount of protein in the urine. This suggests a problem in the ____________.
glomerulus (If the glomerular capillary is damaged, large molecules such as proteins can pass through the filtration membrane and appear in the urine.)
Alcohol acts as a diuretic because it ________.
inhibits the release of ADH
Part B When given to a patient, which of the following substances would increase his or her urinary output?
intravenous saline
The glomerulus differs from other capillaries in the body in that it ________.
is drained by an efferent arteriole
Part C What is the osmolarity of the filtrate at the end of the proximal tubule?
isotonic - 300 mOsm (Yes, the osmolarity of the filtrate would be about 300 mOsm because both solutes and water are reabsorbed in the proximal tubule. As particles are reabsorbed, water follows osmotically.)
Conditions such as diabetes mellitus and starvation are closely linked to __________.
ketonuria (The liver generates large quantities of ketones, as an alternative to glucose, when glucose stores are depleted (during starvation) or when cells are unable to take up glucose from the blood (as in diabetes mellitus). As ketone production increases, excess ketones appear in the urine, a condition called ketonuria. Return to Assignment)
The mechanism that establishes the medullary osmotic gradient depends most on the permeability properties of the ________.
loop of Henle
Antidiuretic hormone (ADH), which regulates urine concentration and dilution, is __________.
lowest before Max exercises (ADH is secreted in response to dehydration, as signaled by high blood osmolality. Max's data indicate that his body is well hydrated before exercise, so ADH secretion is lowest at that time.)
Which cells of the kidney are chemoreceptors that respond to changes in solute content of the filtrate?
macula densa cells
Part B - Properties of the Countercurrent Multiplier Focus your attention on Focus Figure 25.1. Which of the following is NOT a property used to establish the medullary osmotic gradient?
the blood flow through the ascending and descending portions of the vasa recta. (The flow of blood through the ascending and descending portions of the vasa recta does not establish the osmotic gradient. The vasa recta act as countercurrent exchangers to preserve the osmotic gradient.)
Which of the following acts as the trigger for the initiation of micturition (voiding)?
the stretching of the bladder wall
The urinary bladder is composed of ________ epithelium.
transitional
What is the largest component of urine by weight, other than water?
urea
Chapter 25 NCLEX-Style End of Chapter Clinical Case Study Questions 32-Year-Old Diabetic Male on a DiureticLet's return to Kyle Boulard, whom we met in the previous chapter. Mr. Boulard has recovered from his acute diabetic crisis. The last update on his chart before he is discharged includes the following:BP 150/95, HR 75, temperature 37.2°CUrine: pH 6.9, negative for glucose and ketones; 24-hour urine collection reveals 170 mg albumin in urine per day.Mr. Boulard is prescribed a thiazide diuretic and an angiotensin converting enzyme (ACE) inhibitor. He is counseled on the importance of taking his medications regularly and keeping his outpatient follow-up appointments
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IP 2.0: Glomerular Filtration Bonus Question Lisa suffers from kidney stones. One small stone manages to get lodged in the ascending limb of the nephron loop of one of her nephrons. Predict what would happen to the amount of filtrate produced over time by this particular nephron.
Decrease in filtrate production due to an increase in hydrostatic pressure in the capsular space
Building Vocabulary Activity: The Urinary System Part A - Prefixes, Roots, and Suffixes Match these prefixes to their meanings.
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Part B - Vocabulary Terms Match these vocabulary terms to their meanings.
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Concept Map: Nephron Functions - Copy Part A Complete the Concept Map to describe the importance of and mechanisms underlying glomerular filtration, tubular reabsorption, and tubular secretion. Drag the appropriate labels to their respective targets.
answer in image: (Now that you have completed the Concept Map, answer the following questions.)
Art Question Chapter 25 Question 2 Part A What region subdivides to form two or three major calyces and several minor calyces? Select from letters A-D.
answer in image: C
If the Tm for a particular amino acid is 120 mg/100 ml and the concentration of that amino acid in the blood is 230 mg/100 ml, the amino acid will ________.
appear in the urine
The ________ artery lies on the boundary between the cortex and medulla of the kidney.
arcuate
Art Question Chapter 25 Question 20 In what part of the renal tubule are aquaporins scarce or absent so that water CANNOT be reabsorbed?
ascending limb of the nephron loop
Reabsorption of sodium in the medulla by active transport is undertaken by cells that compose which of the following?
ascending nephron loop (Active transport of sodium by the cells of the ascending loop creates the high osmolality of the interstitial fluids in the medulla.)
The __________ collect(s) urine, which drains continuously from the papillae; the urine is then emptied into the __________.
calyces; renal pelvis
Art Question Chapter 25 Question 6 Part A Which vessels supply the cortical tissue of the kidney with blood?
cortical radiate arteries
A disease caused by inadequate secretion of antidiuretic hormone (ADH) by the pituitary gland with symptoms of polyuria is ________.
diabetes insipidus
Upon reaching what point in the nephron is reabsorption (1) dependent upon the body's needs at the time, and (2) regulated by hormones?
distal convoluted tubule
Which structure is INCORRECTLY matched with a function?
nephron loop: reabsorption of urea (Urea in the medullary interstitial fluid is secreted into the ascending thin limb of the nephron loop. This is followed by the reabsorption of urea in the collecting duct, which completes the process of urea recycling.)
During strenuous exercise, Max's body produces lactic acid and his blood pH begins to decline. His kidneys go to work to preserve acid-base balance by doing all of the following EXCEPT __________.
reabsorbing hydrogen (The kidneys secrete, not reabsorb, hydrogen when body pH declines, as happens with lactic acid accumulation. This elimination of acid raises and restores pH.)
The filtration membrane includes all except ________.
renal fascia
Reabsorption of high levels of glucose and amino acids in the filtrate is accomplished by ________.
secondary active transport
Approximately 80% of the energy used for active transport is devoted to the reabsorption of __________.
sodium
It took the diagnosis of high blood pressure (hypertension) at the age of 45 to shock Max into taking better care of himself. A former college football player, he had let himself go, eating too much junk food, drinking too much alcohol, sitting on his chubby bottom for the majority of the last two decades, and even indulging in the frequent habit of smoking cigars. Max's physician had to prescribe two different antihypertensive medications in order to get his blood pressure under control. She also prescribed regular exercise, a low-salt diet, modest alcohol intake, and smoking cessation. Max was scared, really scared. His father had hypertension at a young age as well, and ended up on dialysis before dying from complications of kidney failure. Fortunately for Max, he took his doctor's advice and began a dramatic lifestyle change that would bring him to his present-day situation. Now, at the age of 55, he was a master triathlon athlete who routinely placed among the top five tri-athletes of the same age group in the country. Max's competitive spirit had been ignited by this, but at the same time he wanted to be first among his peers. To that end, he hired Tracey, a Certified Clinical Exercise Specialist, to help him gain the edge he needed to win at the end of the race. His most immediate concern was that he was experiencing problems with dehydration and fatigue because he hadn't found an effective way to drink enough fluids while exercising. Tracey showed Max an impressive array of assessment tools for quantifying and analyzing his physiological state before, during, and after his workouts. One of the tools was urinalysis, which Max found a bit odd, but he dutifully supplied urine samples on a regular, prescribed basis. Tracey explained that Max's hydration status was tricky due to the medication he took to control his hypertension, and that renal status (as measured in the urinalysis) was one of the tools she could use to evaluate his physiological state. Tracey logs the following results of Max's urinalysis immediately after, and six hours after, a rigorous 2-hour run. table below: TIME/COLOR/SPECIFIC GRAVITY/PROTEIN/GLUCOSE/pH Before exercise/pale yellow/1.002/absent/absent/6.0 Immediately after exercise/dark yellow/1.035/small amount/absent/4.5 Six hours after exercise/yellow/1.025/absent/small amount/5.0
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Art Question Chapter 25 Question 18 Calculate the net filtration pressure if blood pressure in the glomerulus is unusually high, around 68 mm Hg.
23 mm Hg
Part E Calculate the net filtration pressure if capillary hydrostatic pressure is 60 mm Hg, capillary osmotic pressure is 25 mm Hg, and capsular hydrostatic pressure is 10 mm Hg.
25 mm Hg (Yes, 60 - (25 + 10) = 25 mm Hg. The two pressures that oppose filtration must be subtracted from the force favoring filtration.)
diabetes insipidus
A disorder of salt and water metabolism marked by intense thirst and heavy urination.
How can an angiotensin converting enzyme inhibitor (ACE inhibitor) such as captopril be effective as an antihypertensive?
ACE inhibitors reduce blood pressure by causing less aldosterone and antidiuretic hormone to be released, resulting in more water output and a lowering of the blood volume, which lowers the blood pressure.
Part E In severe dehydration or blood loss, what would be the levels of ADH and what would be the urine flow rate?
ADH - high; low urine flow rate (0.25 ml/min) (Yes, ADH would be high, causing a large percentage of the water to be reabsorbed. Therefore, the urine flow rate would be low.)
Part D In overhydration, what would be the levels of ADH (high, normal, or low) and what would be the osmolarity of the urine?
ADH - low; 100 mOsm (urine) (Yes, in overhydration, ADH would be very low and the cells of the collecting duct would be relatively impermeable to water and urea. Thus, the final urine would be dilute, having an osmolarity of about 100 mOsm.)
Part B Which of the following statements about ADH (antidiuretic hormone) is correct?
ADH is released by the posterior pituitary gland. (Yes, this is correct. ADH is synthesized in the hypothalamus and stored and released by the posterior pituitary gland.)
IP: Processing of Salt and Water in the Nephron Part A Which of the following statements about aldosterone is NOT correct?
Aldosterone increases sodium reabsorption by increasing the number of Na+-K+ ATPase pumps in the luminal membrane of the proximal tubule. (Yes, this is the incorrect statement. Aldosterone increases the number of Na+-K+ ATPase pumps in the basolateral membrane of the distal tubules and collecting ducts.)
Part D - Long Nephron Loops: Creation of the Medullary Osmotic Gradient Focus your attention on the long nephron loops on the second page of Focus Figure 25.1. Notice the key for active transport, passive transport, and water impermeable in the top figure, and then turn your attention to the figure and arrows at the bottom of the page.Sort the items onto the appropriate limb of the nephron loop figures. All items must be sorted.→→ direction of filtrate flow →
Answer in image: (The long nephron loops of juxtamedullary nephrons first concentrate and then dilute the filtrate. In the descending limb, water is reabsorbed as it moves down its osmotic gradient and concentrates the filtrate. In the ascending limb, solutes (Na+Na+ and Cl−Cl−) are actively pumped out and reabsorbed. Since the ascending limb is impermeable to water, this dilutes the filtrate. The solutes left behind in the surrounding interstitial tissue fluid create a vertical osmotic gradient.)
Part C - Countercurrent Multiplier: Positive Feedback Loop Focus your attention on the positive feedback cycle in Focus Figure 25.1. Drag and drop the labels onto the figure in the correct order of events to complete the positive feedback loop. You may use a label only once or not at all.
Answer in image: (The positive feedback loop "multiplies" the concentration difference between the filtrate and interstitial fluid of the medulla, and it is essential in creating the vertical osmotic gradient in the interstitial fluid of the medulla.)
Focus Figure 25.1: Medullary Osmotic Gradient Part A - Key Players in Medullary Osmotic GradientPart complete Focus your attention on the "key players" outlined in the first part of Focus Figure 25.1. Drag and drop the terms to the appropriate blanks in the sentences. Terms may be used once, more than once, or not at all.
Answer in image: These countercurrent mechanisms establish and maintain an osmotic gradient extending from the cortex through the depths of the medulla. This gradient—the medullary osmotic gradient—allows the kidneys to vary urine concentration dramatically.
Why do you have to carefully monitor certain patients who are on "loop diuretics" to lower their blood pressure?
Certain diuretics are not specific and in addition to getting rid of excess water, additional ions like potassium will be secreted. (Certain diuretics are not specific and in addition to getting rid of excess water, additional ions like potassium will be secreted.)
The descending limb of the loop of Henle is permeable to both solutes and water.
False
Max is curious about the protein content of his urine. Which of these statements provides an accurate basis for Tracey's response, explaining normal conditions?
Few proteins are small enough to pass through the glomerular membrane, but the few that do are reabsorbed. So, proteins are not usually present in urine. (Under normal conditions, only small proteins can make it through the glomerular membrane. When they do, they are reabsorbed in the proximal convoluted tubule by endocytosis. So, proteins are not a typical finding in urine.)
Tracey explains to Max that his transiently elevated blood glucose leads to "spilling" of glucose into his urine. Why does this happen?
Reabsorption of glucose is limited by transport proteins. (Glucose passes freely through the glomerular filter and is usually 100% reabsorbed in the proximal convoluted tubules via transport proteins. However, the transporters have a set cumulative transport maximum beyond which they cannot reabsorb glucose. So, when blood glucose levels are high, too much glucose enters the tubules and some remains in the filtrate to be eliminated in urine.)
Which of the following is NOT one of the things that must happen for micturition to occur?
The extrusor muscle must relax. (There is no "extrusor" muscle; only the detrusor muscle.)
Tracey knows that the large pizza Max consumed just prior to collecting his third urine sample caused a transient increase in his blood glucose levels. What can be accurately said about the relationship between glucose in the blood and the amount of glucose filtered through the glomerular membrane?
The higher the blood glucose concentration, the more glucose is filtered through the glomerular membrane. (Glucose passes freely through the glomerular membrane, so the amount of glucose in the glomerular filtrate correlates with the amount of glucose in the blood.)
Which of the following correctly describes the location of the kidneys?
The kidneys are located along the dorsal wall of the abdominal cavity in the upper lumbar region. The kidneys receive some protection from the lower ribs and perirenal fat pads. The kidneys are retroperitoneal organs. ALL OF THE ABOVE^^ (Review the gross anatomy of the kidneys and the peritoneum in your textbook.)
Aldosterone is a hormone that causes the renal tubules to reclaim sodium ions from the filtrate.
True
Atrial naturetic peptide inhibits sodium reabsorption.
True
Despite the fact that the kidney's intrinsic controls work to maintain a constant GFR, in some situations the body's extrinsic controls will work to override these intrinsic controls in order to maintain systemic blood pressure.
True
Glomerular hydrostatic pressure (HPg) is the chief force pushing water and solutes out of the blood and across the filtration membrane.
True
In the absence of hormones, the distal tubule and collecting ducts are relatively impermeable to water.
True
What is the most direct function of the juxtaglomerular apparatus?
help regulate blood pressure and the rate of blood filtration by the kidneys
Part B What is the primary driving force (pressure) that produces glomerular filtration?
hydrostatic pressure of blood (blood pressure) (Yes, the hydrostatic pressure of blood forces fluid out of the glomerular capillaries.)
The fluid in the glomerular (Bowman's) capsule is similar to plasma except that it does not contain a significant amount of ________.
plasma protein
Part C Which substance would be found in higher concentration if the membrane were damaged?
protein called proteinuria (Yes, large proteins are not normally filtered by a healthy glomerular membrane.)
Where in the nephron does most solute reabsorption occur?
proximal convoluted tubule (Reabsorption takes place mainly in the proximal convoluted tubule of the nephron .)
