Chapter 25: The Urinary System: Study Modules

The reason glucose is detected in the urine of individuals with uncontrolled diabetes is because __________.

the transport maximum for glucose reabsorption has been exceeded

Which of the following best describes glomerular filtration rate (GFR)? the volume of urine leaving the kidneys per minute the volume of blood flowing through the glomerular capillaries per minute the volume of filtrate created by the kidneys per minute the volume of filtrate created at the glomerulus per liter of blood flowing through the glomerular capillaries

the volume of filtrate created by the kidneys per minute Fluid and small solutes that leave the glomerulus are collectively termed filtrate. Glomerular filtration is driven by glomerular hydrostatic pressure (HPg) and produces ~125 ml of filtrate per minute.

Which of the following is NOT a function of the kidneys? to metabolize vitamin D to its active form to carry out gluconeogenesis during prolonged fasting to regulate body fluid by controlling excretion from sweat glands to maintain the proper balance between water and salts and between acids and bases

to regulate body fluid by controlling excretion from sweat glands

Macula densa cells of the juxtaglomerular apparatus (JGA) regulate GFR through which intrinsic mechanism? sympathetic nervous system control tubuloglomerular feedback myogenic mechanism renin-angiotensin mechanism

tubuloglomerular feedback The JGA is a region of the nephron where the afferent arteriole and its associated tubule are closely apposed. This anatomical arrangement allows macula densa cells to adjust GFR according to the NaCl concentration in filtrate. This is called tubuloglomerular feedback because it allows the contents of the tubules (tubulo-) to affect the glomerular filtration rate.

The presence of glucose and ketone bodies in the urine can indicate __________.

untreated diabetes mellitus

Every day the kidneys filter nearly __________ of fluid from the bloodstream.

200 liters

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 50 mm Hg 35 mm Hg 60 mm Hg

25 mm Hg 60 - (25 + 10) = 25 mm Hg. The two pressures that oppose filtration must be subtracted from the force favoring filtration.

Arrange the following structures in the correct sequence in which urine passes through them to the external environment: (1) ureter, (2) renal pelvis, (3) calyx, (4) urinary bladder, (5) urethra.

3, 2, 1, 4, 5

Match the following hormone with its action on the urinary system: Angiotensin II.

A powerful vasoconstrictor that also stimulates the secretion of aldosterone

Match the urinary system feature with its correct characteristic: Creatinine.

A protein metabolite found in skeletal muscle and excreted in urine

Which of the following is not one of the most common causes of incontinence in adults?

A side effect after general anesthesia

Urea transport into the medullary collecting duct is enhanced by __________.

ADH

In severe dehydration or blood loss, what would be the levels of ADH and what would be the urine flow rate? ADH - low; low urine flow rate (0.25 ml/min) ADH - high; high urine flow rate (16 ml/min) ADH - high; low urine flow rate (0.25 ml/min) ADH - low; high urine flow rate (16 ml/min)

ADH - high; low urine flow rate (0.25 ml/min) ADH would be high, causing a large percentage of the water to be reabsorbed. Therefore, the urine flow rate would be low.

How is Na+ reabsorbed?

By active transport using ATP

Match the appropriate pressure in and around the glomerulus with its correct name: Force that pulls fluid back into the glomerulus from the capsular space.

Colloid osmotic pressure (OPgc)

Match the following: Urinary retention.

Common after general anesthesia or hypertrophy of the prostate

Match the following: Cystocele.

Common during childbirth, herniation of the bladder

Match the following: PKD dominant form.

Cysts develop in the kidney though they develop so slowly that they often are not noticed until about 40 years of age.

Match the following part of the nephron with its correct function: Sodium and water reabsorbed under hormonal influence in this region.

Distal convoluted tubule

Match the following vessel found in the kidney with its location: Specialized blood vessel leading away from the glomerulus.

Efferent arteriole

Match the following chemical found in urine with its cause: Usually seen in association with trauma to the kidneys or along the urinary tract.

Erythrocytes

Which of the following is not part of the filtration membrane?

Extraglomerular mesangial cells

The ascending limb of the loop of Henle is permeable to water. True False

False

Capsular hydrostatic pressure is the chief force pushing water and solutes out of the blood and across the filtration membrane. True False

False Glomerular hydrostatic pressure (HPg)

Max needs to drink more water before exercise to avoid dehydration. False True

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.

Which of the following is not associated with primary nocturnal enuresis?

Females over the age of 60 years

Match the correct outcome with its causative glomerular regulation factor: Neural control overcomes the renal autoregulatory mechanisms.

Sympathetic branch

Which of the following is NOT one of the things that must happen for micturition to occur? The internal urethral sphincter must open. The external urethral sphincter must open. The detrusor muscle must contract. The extrusor muscle must relax.

The extrusor muscle must relax

GFR regulation mechanisms primarily affect which of the following? blood osmotic pressure (OPg) glomerular hydrostatic pressure (HPg) capsular osmotic pressure (OPc) capsular hydrostatic pressure (HPc)

glomerular hydrostatic pressure (HPg) Much like other capillaries in the body, hydrostatic pressure within the glomerular capillaries produces net outward movement of fluid. Unique to glomerular capillaries, HPg is consistently higher than other capillaries (~55 mm Hg), which ensures the one-way movement of fluid and solutes out of the glomerulus under normal conditions.

All of the following functions are carried out in the renal tubules, except __________.

filtration

What function is associated with the glomerular capillaries? reabsorption active transport filtration secretion

filtration

Which structure(s) located in the renal cortex filter(s) blood? peritubular capillaries proximal convoluted tubule glomerulus loop of Henle

glomerulus

Which of the following materials is NOT reabsorbed in the nephron loop? water glucose chloride ions sodium ions

glucose Virtually all of the glucose in the filtrate is reabsorbed in the proximal convoluted tubule before reaching the nephron loop.

Renal ptosis may lead to __________.

hydronephrosis due to urine backup

The most important factor affecting the hydrostatic pressure in the glomerulus is __________.

net filtration pressure

Antidiuretic hormone (ADH), which regulates urine concentration and dilution, is __________. highest six hours after Max exercises lowest immediately after Max exercises highest before Max exercises lowest before Max exercises

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.

The renal hilum lies on the __________ surface of the kidney.

medial

The renal pyramids are within which region of the kidney? capsule cortex transitional epithelium medulla

medulla

Which of the following are mechanisms of intrinsic control of glomerular filtration (renal autoregulation)? myogenic mechanism and sympathetic nervous system control myogenic mechanism and tubuloglomerular feedback tubuloglomerular feedback and the renin-angiotensin mechanism sympathetic nervous system control and the renin-angiotensin mechanism

myogenic mechanism and tubuloglomerular feedback Both of these mechanisms occur strictly within kidney (i.e., intrinsic controls). The myogenic mechanism is mediated by smooth muscle within the afferent arteriole. In contrast, tubuloglomerular feedback is mediated by macula densa cells of the juxtaglomerular apparatus (JGA).

The basic functional unit of the kidney is the __________.

nephron

Approximately 80% of the energy used for active transport is devoted to the reabsorption of __________. water potassium sodium glucose

sodium

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) ADH - low; 600 mOsm (urine) ADH - high; 100 mOsm (urine) ADH - high; 600 mOsm (urine)

ADH - low; 100 mOsm (urine) 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.

Which of the following statements about ADH (antidiuretic hormone) is correct? ADH is synthesized by the adrenal gland and works in the kidney. ADH would increase urine volume. ADH is released by the posterior pituitary gland. ADH inserts water channels into the luminal membrane of the proximal tubules.

ADH is released by the posterior pituitary gland. ADH is synthesized in the hypothalamus and stored and released by the posterior pituitary gland.

Match the following vessel found in the kidney with its location: Blood vessel leading directly into the glomerulus.

Afferent arteriole

Through the tubuloglomerular feedback mechanism, how would an increase in filtrate NaCl concentration affect afferent arteriole diameter? Afferent arteriole diameter would increase. Afferent arteriole diameter would stay about the same. Afferent arteriole diameter would decrease.

Afferent arteriole diameter would decrease. High NaCl concentration in the filtrate at the JGA indicates that GFR is too high. By decreasing the diameter of the arteriole delivering blood to the glomerulus, HPg is decreased, resulting in lower GFR.

Which of the following statements about aldosterone is NOT correct? Aldosterone is stimulated by decreased plasma sodium levels and increased plasma potassium levels. Aldosterone increases sodium reabsorption by increasing the number of Na+-K+ ATPase pumps in the luminal membrane of the proximal tubule. Aldosterone is produced in the adrenal cortex. Aldosterone increases the number of passive sodium channels in the luminal membrane of the distal tubule and collecting duct, thus aiding sodium reabsorption.

Aldosterone increases sodium reabsorption by increasing the number of Na+-K+ ATPase pumps in the luminal membrane of the proximal tubule. Aldosterone increases the number of Na+-K+ ATPase pumps in the basolateral membrane of the distal tubules and collecting ducts.

Match the urinary system feature with its correct characteristic: Uric acid.

An end product from nucleic acid metabolism

Which of the following homeostatic imbalances is indicative that glomerular blood pressure may be too low to cause filtration?

Anuria

Match the following: Renal infarct.

Area of dead, or necrotic, renal tissue

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. All proteins are negatively charged and too large to pass through the glomerular membrane. So, proteins are not normally present in urine. Most proteins pass through the glomerular membrane and are present in varying amounts in urine. Most proteins pass through the glomerular membrane and are reabsorbed. So, proteins are not present in urine.

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.

In what part of the nephron is plasma filtered?

Glomerular capsule

Match the appropriate pressure in and around the glomerulus with its correct name: The force of blood against the walls of the glomerular capillaries.

Glomerular hydrostatic pressure (HPgc)

Match the following part of the glomerular structure with its correct description: Large knot of capillaries at the beginning of the nephron.

Glomerulus

Match the following: PKD recessive form.

Half of newborns die just after birth, and survivors generally develop renal failure in early childhood.

Match the following: Nephrotoxin.

Heavy metal, organic solvent, or bacterial toxin that is toxic to the kidneys

Match the appropriate pressure in and around the glomerulus with its correct name: Pressure exerted by fluid in the glomerular capsule against the fluids coming out of the glomerulus.

Hydrostatic pressure of the capsular space

__________ are the structural and functional units of the kidneys, which carry out the processes that form urine.

Nephrons

Match the correct outcome with its causative glomerular regulation factor: Afferent arterioles dilate in response to a fall in blood pressure.

Increases GFR

Match the following: Urethritis.

Inflammation of urethra

Which of the following substances is the standard substance used to measure the GFR?

Inulin

Which of the following statements about the urinary system is incorrect?

It metabolizes vitamin C to its active form.

Match the urinary system feature with its correct characteristic: Aldosterone-induced Na+ absorption.

Its reabsorption occurs with K+ efflux

Match the following chemical found in urine with its cause: Elevated levels are evidence of starvation or untreated diabetes mellitus.

Ketone bodies

Match the following: Diabetes insipidus.

Lack of ADH receptors

Match the following: Acute glomerulonephritis.

Leads to increased permeability of the filtration membrane

Match the urinary term with its characteristic: Juxtamedullary nephrons.

Long nephrons that deeply invade the medulla

Which of the regions of the nephron do not absorb Na+ by primary active transport?

Loop of Henle, descending limb

Given the correlation between urine color and urine concentration, which of the following statements is true about Max's urine? Max's urine is least concentrated six hours post-exercise. Max's urine is most concentrated before exercise. Max's urine is most dilute before exercise. Max's urine is most dilute immediately post-exercise.

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.

Match the following: Stress incontinence.

Most common during pregnancy when the heavy uterus stretches the muscles of the pelvic floor

Match the correct outcome with its causative glomerular regulation factor: Afferent arterioles constrict in response to a rise in blood pressure, thus restricting the flow of blood into the glomerulus.

Myogenic mechanism

Match the appropriate pressure in and around the glomerulus with its correct name: The relationship of all the pressures that act at the level of the glomerulus; responsible for the formation of filtrate.

Net filtration pressure

Match the urinary system feature with its correct characteristic: Glucose.

Not normally found in the urine

Match the following: Dysuria.

Painful urination

Match the following vessel found in the kidney with its location: Capillaries that surround the tubules of the nephron.

Peritubular capillaries

Match the following hormone with its action on the urinary system: Aldosterone.

Promotes reabsorption of sodium at the distal convoluted tubule

Which substance would not normally be expected in urine?

Protein

Match the following part of the nephron with its correct function: Primary site of glucose and amino acid reabsorption.

Proximal convoluted tubule

Tracey explains to Max that his transiently elevated blood glucose leads to "spilling" of glucose into his urine. Why does this happen? Tubule cells inhibit glucose production when blood levels are elevated. The tubule cells are unable to reabsorb any glucose that enters the filtrate. The tubule cells actively secrete excess glucose into the filtrate. Reabsorption of glucose is limited by transport proteins.

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.

Match the following hormone with its action on the urinary system: ADH.

Regulates water reabsorption at the collecting duct

Which of the following is false with regards to renal ptosis?

Renal ptosis is caused by excessive fat deposits in the abdomen.

Match the correct outcome with its causative glomerular regulation factor: A drop in systemic blood pressure triggers the release of an enzyme by the kidneys; the release of the enzyme triggers this regulatory system.

Renin-angiotensin system

Which process results in increased blood pressure in response to hormone release?

Renin-angiotensin-aldosterone mechanism

Which of the following is not a physical characteristic of freshly voided urine in a healthy person?

Slightly basic in pH

Match the urinary term with its characteristic: Macula densa cells.

Specialized chemoreceptors

Match each urinary term with its characteristic: Juxtaglomerular cells.

Specialized mechanoreceptors

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? Glucose requires a transport protein to get through the glomerular membrane, so glucose in the filtrate cannot increase even when blood glucose concentration is high. Only small glucose molecules can filter through the glomerular membrane, but high blood glucose concentration increases the amount of glucose in the filtrate. The glomerular membrane prevents glucose from entering the filtrate unless blood glucose concentration is abnormally high. The higher the blood glucose concentration, the more glucose is 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.

Match the following: Horseshoe kidney.

The kidneys fuse across the midline.

Match the following: Hypospadias.

The urethral opening is on the ventral (inferior) surface of the penis.

Under normal conditions, the proximal convoluted tubule (PCT) reabsorbs all of the glucose, lactate, and amino acids in the filtrate and 65% of the Na+ and water. True False

True

Match the correct outcome with its causative glomerular regulation factor: A drop in flow rate through the nephron or a rise in the osmolality of filtrate triggers regulation by this mechanism.

Tubuloglomerular feedback mechanism

Which of the following is true of urinary tract infections.

UTI infection is more likely with use of spermicides.

Which of the following is incorrect with regards to renal pathologies?

Untreated, the kidney may be severely damaged and antibiotic therapy often fails to treat the disorder.

Which of the following substances is the largest component of urine by weight after water?

Urea

Which structure is the muscular tube that delivers urine to the bladder?

Ureter

Match the following: Overflow incontinence.

Urine dribbles from the urethra whenever the bladder overfills

Match the following: Overflow incontinence.

Usually a result of weakened pelvic muscles

Match the urinary system feature with its correct characteristic: Urea.

Waste that actually helps form the medullary gradient

The blood supply to the nephron is the __________.

afferent arteriole

The myogenic mechanism of renal autoregulation primarily involves smooth muscle in which blood vessels? afferent arterioles systemic arterioles efferent arterioles glomeruli

afferent arterioles By regulating afferent arteriole diameter, the myogenic mechanism affects HPg and therefore GFR. Under normal physiological conditions, this intrinsic control works to maintain GFR despite moderate changes in systemic blood pressure.

The reabsorption of sodium in the DCT is regulated primarily by __________. aldosterone and ANP aldosterone parathyroid hormone renin and angiotensin

aldosterone and ANP Aldosterone increases Na+ reabsorption, and atrial natriuretic peptide (ANP) inhibits Na+ reabsorption.

The rate of kidney filtrate formation would normally be dependent upon all of the following factors except __________. systemic blood pressure filtration membrane integrity blood calcium level renal artery/arteriole diameters

blood calcium level

Which of the following substances is not normally found in filtrate? ions, such as sodium and potassium nitrogenous waste particles, such as urea water and small solutes blood cells and large particles

blood cells and large particles Both blood cells and large particles, such as proteins, are not allowed to filter through a healthy glomerular membrane.

Filtrate in a typical healthy nephron will NEVER include __________. glucose amino acids and fatty acids K+ and Na+ ions blood cells and proteins

blood cells and proteins Proteins and blood cells are too large to pass through the filtration membrane between the blood and the glomerular capsule.

How are nutrient molecules such as glucose and amino acids reabsorbed through the apical surfaces of the tubule epithelia? by osmosis by secondary active transport by primary active transport by simple diffusion

by secondary active transport Glucose is reabsorbed via symport carrier proteins via secondary active transport with Na+.

The __________ collect(s) urine, which drains continuously from the papillae; the urine is then emptied into the __________. calyces; renal pelvis renal pyramids; renal pelvis renal pelvis; calyces renal pyramids; calyces

calyces; renal pelvis

The energy needed for secondary active transport is provided by the __________.

concentration gradient established by Na+

If the afferent arteriole constricts while the efferent arteriole remains unchanged, the glomerular filtration rate __________.

decreases

Upon reaching what point in the nephron is reabsorption (1) dependent upon the body's needs at the time and (2) regulated by hormones? proximal convoluted tubule distal convoluted tubule ascending limb of the loop of Henle descending limb of the loop of Henle

distal convoluted tubule

External chemicals that enhance urinary output are called __________.

diuretics

The __________ is a skeletal muscle under conscious control that allows urine to leave the bladder. internal urethral sphincter external urethral orifice prostatic urethra external urethral sphincter

external urethral sphincter

What is the primary driving force (pressure) that produces glomerular filtration? gravity hydrostatic pressure of blood (blood pressure) colloid osmotic pressure of blood

hydrostatic pressure of blood (blood pressure) The hydrostatic pressure of blood forces fluid out of the glomerular capillaries.

All of the following would stimulate the release of renin from granular cells, except __________.

inhibition by the macula densa cells

What does a high concentration of NaCl in the renal tubule at the juxtaglomerular apparatus (JGA) most likely indicate? insufficient NaCl reabsorption due to low GFR excessive NaCl reabsorption due to low GFR insufficient NaCl reabsorption due to high GFR excessive NaCl reabsorption due to high GFR

insufficient NaCl reabsorption due to high GFR After glomerular filtration, NaCl is actively reabsorbed at many locations along the renal tubule. If the filtrate is moving through the tubule quickly, less reabsorption is possible, so more NaCl gets left behind. This means that at the JGA, the NaCl concentration within the filtrate will be high.

When given to a patient, which of the following substances would increase his or her urinary output? antidiuretic hormone intravenous saline aldosterone albumin

intravenous saline

What is the osmolarity of the filtrate at the end of the proximal tubule? isotonic - 300 mOsm hypertonic - 1200 mOsm hypotonic - 100 mOsm hypertonic - 600 mOsm

isotonic - 300 mOsm 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.

The major calyces are the __________.

large branches of the renal pelvis

A powerful vasoconstrictor that also stimulates the secretion of aldosterone

less urine is produced

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 increase net filtration would not be altered net filtration would decrease

net filtration would decrease Because osmotic pressure opposes filtration, increasing osmotic pressure would decrease net filtration.

The renal __________ is continuous with the ureter.

pelvis

The __________ cushions the kidney and helps attach it to the posterior body wall.

perirenal fat capsule

Which substance would be found in higher concentration if the membrane were damaged? glucose chloride protein creatinine

protein Large proteins are not normally filtered by a healthy glomerular membrane.

Where in the nephron does most solute reabsorption occur? collecting duct glomerulus distal convoluted tubule proximal convoluted tubule

proximal convoluted tubule

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 bicarbonate generating new bicarbonate reabsorbing hydrogen secreting hydrogen

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.

Under normal resting conditions, the __________ arteries deliver one-fourth of the total cardiac output (about 1200 ml) to the kidneys each minute.

renal

All of the following are layers of the filtration membrane in the glomerular membrane, except the __________.

renal capsule

Granular cells of the juxtaglomerular apparatus (JGA) regulate GFR indirectly through which mechanism? myogenic mechanism renin-angiotensin mechanism sympathetic nervous system controls tubuloglomerular feedback mechanism

renin-angiotensin mechanism When systemic blood pressure decreases, granular cells release renin which ultimately causes the formation of angiotensin II. Angiotensin II causes widespread vasoconstriction of systemic arterioles and the increase of blood volume due to aldosterone release.