Deck 14: The Kidneys and Regulation of Water and Inorganic Ions

Question 1

Where do Na⁺/K⁺ ATPase pumps play an active role in reabsorbing Na⁺?

A)in Bowman's capsule epithelial cells,facing the interior of Bowman's space
B)in the basolateral membrane of cells of the cortical collecting duct
C)in the apical membrane of epithelial cells of the proximal tubule
D)in the luminal membrane of epithelial cells of the distal convoluted tubule
E)in the basolateral membrane of endothelial cells of peritubular capillaries

Answer 1

B

Question 2

Which is TRUE regarding renal tubular reabsorption?

A)Reabsorption of Na+ from the proximal tubule occurs as a result of water reabsorption.
B)Reabsorption of glucose saturates at a maximum transport rate.
C)Urea reabsorption cannot occur at any point along the nephron.
D)Toxic substances are removed from the body by reabsorption from peritubular capillaries into the proxmial tubule.
E)Reabsorption of Na⁺ only occurs from nephron regions that come after the descending limb of the loop of Henle.

Answer 2

B

Question 3

Which correctly describes a basic renal process?

A)Fluid is filtered from Bowman's capsule into the glomerulus.
B)Substances are secreted from the tubule into the peritubular capillaries.
C)Substances are reabsorbed from the capillaries into the tubular lumen.
D)Substances are actively secreted from glomerular capillaries into Bowman's capsule.
E)Fluid moves by bulk flow from glomerular capillaries into Bowman's space.

Answer 3

E

Question 4

Which of the following does NOT correctly describe kidney function?

A)They contribute significantly to long-term regulation of arterial blood pressure by maintaining the proper plasma volume.
B)They produce urine of a constant composition at all times,in order to maintain homeostasis of extracellular fluid.
C)They excrete metabolic waste products.
D)They assist in maintaining proper acid-base balance in the body.
E)They secrete hormones.

Question 5

Which is TRUE about the juxtaglomerular apparatus?

A)It is composed of parts of the ascending limb of the loop of Henle and the efferent arteriole.
B)It is composed of glomerular capillaries and the macula densa.
C)It is the site of renin secretion.
D)It is created by the the junction between the proximal tubule and the afferent arteriole.
E)It is composed of cells that secrete atrial natriuretic peptide and cells that secrete norepinephrine.

Question 6

Which of the following is TRUE about how water is handled by the nephron?

A)Water is filtered out of glomerular capillaries by bulk flow.
B)Water is actively reabsorbed from the proximal tubule,and Na+ follows down its diffusion gradient.
C)Water is actively secreted into the descending loop of Henle.
D)The permeability of the ascending limb of the loop of Henle is modified by vasopressin.
E)Vasopressin inserts pumps in the collecting duct membrane that move water against its concentration gradient.

Question 7

Constriction of the ________ decreases hydrostatic pressure in _________.

A)afferent arterioles,glomerular capillaries
B)efferent arterioles,proximal convoluted tubules
C)renal vein,peritubular capillaries
D)efferent arterioles,glomerular capillaries
E)efferent arterioles,Bowman's capsule

Question 8

Which is NOT a transport mechanism typically seen in renal tubular epithelial cells?

A)cotransport proteins in the luminal membrane of the proximal tubule that move Na+ and glucose from the proximal tubule into epithelial cells
B)transport proteins that move glucose by facilitated diffusion from inside of proximal tubule cells into the renal interstitial fluid
C)ion channels that allow Na+ to move by diffusion from the lumen of the proximal tubule into epithelial cells
D)Na⁺-K⁺ ATPase pumps in the luminal membrane of proximal tubule epithelial cells that move Na⁺ from inside the cell into the tubule and K⁺ from the tubule lumen into the cell
E)countertransport proteins that move Na⁺ into proximal tubule epithelial cells while moving H⁺ from the cells into the lumen

Question 9

Which equation is equal to the net glomerular filtration pressure?

A)= hydrostatic pressure in glomerular capillaries - hydrostatic pressure in Bowman's capsule - osmotic pressure due to protein in Bowman's capsule
B)= osmotic pressure due to protein in plasma - hydrostatic pressure in glomerular capillaries - hydrostatic pressure in Bowman's capsule
C)= hydrostatic pressure in glomerular capillaries + hydrostatic pressure in Bowman's capsule + osmotic pressure due to protein in plasma
D)= hydrostatic pressure in glomerular capillaries + hydrostatic pressure in Bowman's capsule - osmotic pressure due to protein in plasma
E)= hydrostatic pressure in glomerular capillaries - hydrostatic pressure in Bowman's capsule - osmotic force due to proteins in plasma

Question 10

Which of the following is least likely to be filtered into Bowman's capsule in a normal,healthy person?

A)glucose
B)plasma protein
C)sodium
D)urea
E)bicarbonate ion

Question 11

Which of the following statements concerning the process of glomerular filtration is correct?

A)The hydrostatic pressure in Bowman's space opposes filtration.
B)The glomerular filtration rate is limited by a transport maximum.
C)All of the plasma that enters the glomerular capillaries is filtered.
D)The osmotic force due to plasma proteins favors filtration.
E)The hydrostatic pressure in glomerular capillaries opposes filtration.

Question 12

Which one of the following substances is LEAST dependent on the kidney for regulation of its plasma concentration?

A)water
B)Na⁺
C)K⁺
D)HPO₄^-
E)glucose

Question 13

Which correctly describes the composition of the glomerular filtrate?

A)It is identical to urine,but has a much smaller flow rate.
B)It is identical to urine,but has a much larger flow rate.
C)It is identical to blood plasma,except it lacks red blood cells.
D)It is highly similar to plasma,except it contains plasma proteins.
E)It is highly similar to plasma,except it does not contain plasma proteins.

Question 14

Which of the following describes tubular reabsorption in the kidney?

A)the movement of substances from the peritubular capillaries into the tubular fluid
B)the movement of substances from the proximal tubule into the loop of Henle
C)transepithelial transport from the lumen of the tubule into renal interstitial fluid
D)movement of Na⁺,Cl^- and water from glomerular capillaries into Bowman's capsule
E)transport of solutes from the renal medullary interstitium into the collecting duct

Question 15

Which of the following substances undergo renal tubular secretion?

A)Ca²⁺
B)Na⁺
C)K⁺
D)H₂0

Question 16

Which is true for a man who is in balance for total body water?

A)he must ingest more water than is lost in the urine
B)he must ingest more water than is lost by all output pathways combined
C)he must ingest less water than is lost in the urine
D)the water filtered into Bowman's capsule must be 100% reabsorbed
E)the amount ingested plus that metabolically produced must equal the amount of water in the urine

Question 17

The amount of a substance that is excreted in the urine is equal to the amount that is ________ plus the amount that is ________ minus the amount that is ________.

A)filtered; reabsorbed; secreted
B)reabsorbed; filtered; secreted
C)secreted; reabsorbed; filtered
D)filtered; secreted; reabsorbed
E)reabsorbed; secreted; filtered

Question 18

Compared to the normal plasma osmolarity,the tubular fluid is ________ as it enters Bowman's space,______ at the beginning of the loop of Henle,______ at the tip of the loop and ________ at the beginning of the distal convoluted tubule.

A)isosmotic; hyperosmotic; hyperosmotic; isosmotic
B)isosmotic; isosmotic; hypoosmotic; hypoosmotic
C)isosmotic; isosmotic; hyperosmotic; hypoosmotic
D)isosmotic; isosmotic; hypoosmotic; hyperosmotic
E)isosmotic; isosmotic; hyperosmotic; isosmotic

Question 19

All of the following substances are present in proximal tubular fluid in the kidney,but which one is NOT normally present in urine?

A)Ca²⁺
B)H⁺
C)K⁺
D)HPO4^-
E)glucose

Question 20

Which is NOT a function of the kidneys in maintaining homeostasis?

A)regulation of extracellular fluid osmolarity
B)regulation of blood hydrogen ion concentration
C)regulation of blood glucose concentration
D)regulation of extracellular fluid volume
E)regulation of blood K⁺ concentration

Question 21

Which would occur as a result of a decrease in the total body content of Na⁺?

A)an increase in plasma volume,which induces an increase in GFR and Na⁺ reabsorption rate
B)a decrease in plasma volume,which induces an increase in GFR and Na⁺ reabsorption rate
C)an increase in plasma volume,which induces an increase in GFR and a decrease in Na⁺ reabsorption rate
D) a decrease in plasma volume,which induces a decrease in GFR and Na⁺ reabsorption rate
E) a decrease in plasma volume,which induces a decrease in GFR and an increase in Na⁺ reabsorption rate

Question 22

Which is NOT true about the countercurrent multiplier system of the kidney?

A)It creates a hyperosmolar medullary interstitium that allows the kidneys to form hypertonic urine.
B)The descending loop of Henle is permeable to water.
C)There is active transport of sodium and chloride out of the ascending limb of the loop of Henle.
D)The ascending loop of Henle is not permeable to water.
E)The fraction of filtered NaCl reabsorbed from the ascending limb equals the fraction of filtered water reabsorbed from the descending limb.

Question 23

What region of the nephron reabsorbs about two-thirds of filtered Na⁺ and Cl^-?

A)ascending loop of Henle
B)glomerulus
C)proximal convoluted tubule
D)distal convoluted tubule
E)collecting duct

Question 24

Which would result from ingesting a large amount of salt?

A)urine osmolarity would decrease
B)atrial natriuretic factor secretion would decrease
C)firing by hypothalamic osmoreceptors would decrease
D)secretion of atrial natriuretic factor would increase
E)secretion of vasopressin would decrease

Question 25

Which is TRUE about the hormone vasopressin (also known as antidiuretic hormone,ADH)?

A)It is a peptide hormone released from the adrenal gland.
B)It triggers insertion of aquaporins into the apical membranes of collecting duct cells.
C)It promotes the excretion of more water in the urine.
D)It stimulates the excretion of K⁺ in the urine.
E)It's main function is to trigger the secretion of aldosterone.

Question 26

In the presence of aldosterone,which nephron region reabsorbs the greatest fraction of the filtered Na⁺?

A)proximal tubule
B)macula densa
C)descending limb of the loop of Henle
D)distal convoluted tubule
E)cortical collecting duct

Question 27

Which of the following would cause a decrease in the excretion of Na⁺ and water?

A)increased hydrostatic pressure in the afferent renal arterioles
B)increased mean arterial blood pressure
C)increased atrial distension
D)decreased aldosterone secretion
E)decreased atrial natriuretic peptide secretion

Question 28

Which of the following statements regarding renal handling of Na⁺ is correct?

A)In the proximal tubule,Na⁺ is actively transported across the luminal membrane of the tubular epithelial cells.
B)Atrial natriuretic factor increases Na⁺ reabsorption.
C)In the absence of aldosterone,Na⁺ will be secreted by the cortical collecting ducts.
D)Na⁺ is actively reabsorbed in the ascending limb of the loop of Henle.
E)Without vasopressin,the collecting duct is impermeable to Na⁺.

Question 29

Water and NaCl reabsorbed from the loop of Henle directly re-enter what blood vessels?

A)vasa recta
B)afferent arterioles
C)efferent arterioles
D)cortical peritubular capillaries
E)collecting ducts

Question 30

Which of the following organs is the main site of aldosterone secretion?

A)kidneys
B)adrenal glands
C)systemic and pulmonary blood vessels
D)liver
E)the atria of the heart

Question 31

In what segment of the nephron is the greatest fraction of filtered water reabsorbed?

A)the proximal tubule
B)the ascending limb of the loop of Henle
C)the distal convoluted tubule
D)the collecting ducts
E)the descending limb of the loop of Henle

Question 32

In which region of the nephron does the fractional reabsorption of water vary the most in response to variation in the state of hydration?

A)the glomerulus
B)the proximal convoluted tubule
C)the loop of Henle
D)the distal convoluted tubule
E)the collecting duct

Question 33

Which correctly describes renin?

A)It is secreted by juxtaglomerular cells in renal afferent arterioles.
B)Its secretion is enhanced by high levels of Na⁺ in the macula densa.
C)Its secretion is stimulated by elevated blood pressure in the renal afferent arterioles.
D)It acts on the adrenal cortex to stimulate aldosterone secretion.
E)It is secreted by the liver in response to low blood pressure.

Question 34

Which would occur if a person lost the ability to synthesize vasopressin?

A)The ability to reabsorb water in the proximal tubule would be lost.
B)The excretion of glucose in the urine would increase.
C)The urine would become hypoosmotic compared to plasma.
D)The urine production would decrease dramatically,and the urine osmolarity would be hypertonic compared to plasma.
E)Blood pressure would increase significantly.

Question 35

How does the renal countercurrent multiplier mechanism allow the creation of a concentrated urine?

A)It transports NaCl from the medullary interstitium into the collecting duct,which directly increases the osmolarity of the urine.
B)It transports urea from the medullary interstitium into the collecting duct,which directly increases the osmolarity of the urine.
C)By concentrating NaCl in the renal medullary interstitium,it allows water to be reabsorbed from the collecting ducts when vasopressin is present.
D)By pumping NaCl and urea into the ascending limb of the loop of Henle,it raises the solute load,which turns into a concentrated urine once water is extracted from the collecting duct.
E)When anti-diuretic hormone is present,it stimulates the pumping of NaCl from the medullary interstitium and water follows,concentrating the urine.

Question 36

Which of the following would be most likely to increase GFR?

A)sympathetic stimulation of afferent arteriolar smooth muscle
B)constricting efferent arterioles
C)a decrease in plasma volume
D)an increase in the concentration of plasma proteins
E)increased secretion of renin

Question 37

In the condition diabetes mellitus,why does glucose appear in the urine?

A)The plasma concentration of glucose becomes so high that it diffuses from peritubular capillaries into the proximal tubule,down its concentration gradient.
B)The filtered load of glucose becomes greater than the tubular maximum for its reabsorption.
C)Without the hormone insulin,glucose cannot enter proximal tubule epithelial cells.
D)The rate of tubular secretion of glucose becomes greater than the sum of glucose filtration and reabsorption.
E)Without insulin,the glomerular filtration barrier becomes extremely leaky to glucose,which is not normally fiterable.

Question 38

Which of these is deficient in the disease,diabetes insipidus?

A)ACTH
B) vasopressin
C) atrial natriuretic factor
D) angiotensin II
E) insulin

Question 39

What is the rate-limiting (regulated)step for stimulating the secretion of aldosterone?

A)conversion of angiotensin I to angiotensin II in the blood
B)secretion of angiotensinogen by the liver
C)conversion of angiotensinogen to angiotensin I in the blood
D)secretion of ACTH by the anterior pituitary
E)secretion of angiotensin II by the kidney

Question 40

Which of the following most accurately describes the renal transport of Na⁺?

A)Na⁺ is actively transported in all segments of the tubule.
B)Primary active transport of Na⁺ allows for secondary active transport of glucose and H⁺ in the proximal tubule.
C)Most of the Na⁺ transport occurs in the distal convoluted tubule and collecting ducts.
D)Na⁺ is actively secreted into the nephron lumen by cells in the cortical collecting ducts.
E) Na⁺ is actively transported across the luminal membrane of proximal tubule cells in exchange for K⁺,by Na⁺/K⁺ ATPase pumps.

Question 41

Which of the following most accurately describes the actions of aldosterone?

A)Aldosterone increases Na⁺ secretion and K⁺ reabsorption in the cortical collecting ducts.
B)Aldosterone increases Na⁺ reabsorption and K⁺ secretion in the proximal tubule.
C)Aldosterone decreases Na⁺ reabsorption and K⁺ secretion in the cortical collecting ducts.
D)Aldosterone increases Na⁺ secretion and K⁺ reabsorption in the proximal tubule.
E)Aldosterone increases Na⁺ reabsorption and K⁺ secretion in the cortical collecting ducts.

Question 42

Which of these directly results from hypoventilation?

A)metabolic acidosis
B)respiratory acidosis
C)metabolic alkalosis
D)respiratory alkalosis

Question 43

Most of the reabsorption of filtered calcium is unregulated and occurs in the ________,but an additional amount can be reabsorbed in the _________,depending on the plasma concentration of parathyroid hormone.

A)proximal convoluted tubule,distal convoluted tubule
B)distal convoluted tubule,proximal convoluted tubule
C)proximal convoluted tubule,descending loop of Henle
D)distal convoluted tubule,medullary collecting ducts
E)distal convoluted tubule,renal corpuscle

Question 44

When blood Ca²⁺ levels fall below normal,in what ways do the kidneys help restore them toward normal?

A)by increasing 1,25-dihydroxyvitamin D3 formation,decreasing tubular phosphate reabsorption,and increasing tubular Ca²⁺ reabsorption
B)by increasing 1,25-dihydroxyvitamin D3 formation,increasing tubular phosphate reabsorption,and increasing tubular Ca²⁺ reabsorption
C)by decreasing 1,25-dihydroxyvitamin D3 formation,increasing tubular phosphate reabsorption,and increasing tubular Ca²⁺ reabsorption
D)Increasing 1,25-dihydroxyvitamin D3 formation and increasing secretion of parathyroid hormone
E)by increasing renal secretion of parathyroid hormone and increasing bone resorption

Question 45

Which of the following statements about renal control of blood acid/base balance is TRUE?

A)Increased metabolism of glutamine by renal tubular cells increases the plasma bicarbonate concentration.
B)Excretion in the urine of hydrogen bound to phosphate buffers decreases plasma bicarbonate concentration.
C)H⁺ that binds to filtered bicarbonate in the tubular fluid is excreted in the urine.
D)When hypoventilation occurs at the lungs,the kidneys compensate by reducing glutamine metabolism.
E)The kidneys compensate for a metabolic alkalosis by increasing CO₂ production.

Question 46

Which stimulates vasopressin secretion?

A)increased plasma osmolarity
B)increased plasma volume
C)ingestion of alcohol
D)decreased aldosterone secretion
E)increased pressure in afferent arterioles

Question 47

Which of the following types of drugs would inhibit spontaneous emptying of the bladder (incontinence)?

A)drugs that enhance the effects of parasympathetic neurons on the detrusor muscle
B)drugs that block the effects of parasympathetic neurons on the detrusor muscle
C)drugs that inhibit the effects of sympathetic neurons on the internal urethral sphincter
D)drugs that inhibit the effects of somatic neurons on the bladder
E)drugs that inhibit the action of sympathetic neurons on the external urethral sphincter

Question 48

How would the kidneys respond to hypoventilation?

A)increasing secretion of H⁺ and increasing production of newHCO₃^-
B)increasing secretion of H⁺ and decreasing reabsorption of HCO₃^-
C)decreasing secretion of H⁺ and increasing production of new HCO₃^-
D)decreasing secretion of H⁺ and decreasing reabsorption of HCO₃^-
E)increasing excretion of CO₂

Question 49

Which of the following statements regarding Ca²⁺ homeostasis is true?

A)Parathyroid hormone directly stimulates Ca²⁺ reabsorption by the kidneys.
B)Parathyroid hormone directly stimulates Ca²⁺ absorption from the GI tract.
C)In the absence of parathyroid hormone,plasma Ca²⁺ levels would be abnormally low,resulting in the hyperpolarization of nerve and muscle membranes.
D)When plasma Ca²⁺ increases above normal,the secretion of parathyroid hormone increases.
E)Vitamin D decreases the renal tubular reabsorption of Ca²⁺.

Question 50

Which would result in the greatest stimulation of aldosterone secretion?

A)increasing plasma K+ concentration and decreasing plasma angiotensin II concentration
B)decreasing plasma K+ concentration and increasing plasma angiotensin II concentration
C)increasing plasma Na⁺ concentration and increasing plasma volume
D)increasing plasma K⁺ concentration and increasing plasma angiotensin II concentration
E)decreasing plasma Na⁺ concentration and decreasing plasma angiontensin II concentration

Question 51

Which of these would result in an increase in the osmolarity of urine?

A)increased levels of vasopressin in the plasma
B)increased levels of aldosterone in the plasma
C)decreased transport of Na⁺ and Cl^- by the ascending limb of the loop of Henle
D)ingestion of a large volume of pure water
E)decreased urea permeability of the medullary collecting duct

Question 52

If a patient with pulmonary disease began to hypoventilate,how would plasma levels of [H⁺],HCO3^-,and P_CO2 be changed,compared to normal?

A)increased [H⁺],increased P_CO2,and increased [HCO₃^-]
B)increased [H⁺],increased P_CO2,and decreased [HCO₃^-]
C)increased [H⁺],decreased P_CO2,and decreased [HCO₃^-]
D)decreased [H⁺],increased P_CO2,and decreased [HCO₃^-]
E)decreased [H⁺],decreased P_CO2,and decreased [HCO₃^-]

Question 53

The loss of 0.5 L of sweat would stimulate a greater increase in vasopressin secretion than the loss of an equal amount of blood plasma over the same period of time.This statement is:

A)true,because sweat is hyperosmotic to plasma.
B)true,because sweat is hypoosmotic to plasma.
C)false,because sweat is hypoosmotic to plasma.
D)false,because sweat is isosmotic to plasma.
E)false,because sweat is hyperosmotic to plasma.

Question 54

After prolonged exertion in a hot climate,baroreceptors would ________ firing,leading to ________ secretion of ________ and thus ________ renal reabsorption of ________.

A)increase; increased; renin; increased; Na⁺
B)decrease; increased; renin; decreased; Na⁺
C)decrease; increased; vasopressin; increased; water
D)increase; decreased; vasopressin; decreased; water
E)decrease; decreased; vasopressin; increased; water

Question 55

A man with hypertension takes a diuretic that is not potassium-sparing,and he does not increase his ingestion of potassium.Which of the following side-effects would the drug be most likely to cause?

A)increased blood volume
B)hyperpolarized neuronal cell membranes
C)hyperkalemia
D) cardiac arrhytmia
E) All of these side effects would occur.

Question 56

What change in renal regulation of H⁺ would help compensate for a metabolic acidosis?

A)a decrease in the filtered load of H⁺
B)an increase in the urinary pH
C)a decrease in the tubular production of ammonia
D)a decrease in the amount of H+ secreted in the proximal tubule
E)an increase in the production of new plasma HCO₃^-

Question 57

Which of the following symptoms would a patient with a deficiency of parathyroid hormone be most likely to experience?

A)low plasma calcium levels and decreased muscular excitability
B)low plasma calcium levels and increased muscular excitability
C)high plasma calcium levels and decreased muscular excitability
D)high plasma calcium levels and increased muscular excitability
E)high plasma calcium levels and abnormally weak bones

Question 58

Which of the following drugs is least likely to decrease blood pressure?

A)a drug that interferes with aldosterone synthesis
B)a drug that is an agonist of atrial natriuretic factor
C)a drug that decreases sympathetic stimulation of renal arterioles
D)a drug that enhances the activity of angiotensin-converting enzyme
E)a drug that decreases liver production of angiotensinogen

Question 59

Which would you observe in a person experiencing metabolic acidosis?

A)decreased renal secretion of hydrogen ion
B)decreased renal reabsorption of bicarbonate ion
C)increased plasma PCO₂
D)decreased urinary pH
E)decreased urinary ammonium

Question 60

Which would NOT be caused by a decrease in plasma Ca²⁺ levels in an otherwise normal person?

A)an increase in plasma parathyroid hormone levels
B)an increase in plasma 1,25-dihydroxyvitamin D3 levels
C)an increase in nerve and muscle excitability
D)a decrease in the filtered load of Ca²⁺
E)an increase in bone density

Question 61

The distal convoluted tubules drain directly into the renal pelvis,which in turn drains into the ureter,a tube that carries urine to the bladder.

Question 62

Total-body balance of water and Na⁺ is largely maintained by regulating urinary loss of these substances.

Question 63

The countercurrent mechanism of the kidney enables the formation of hypertonic urine.

Question 64

If water intake (ingestion)is decreased,the kidney can decrease the amount of water excreted in urine by increasing the amount of water reabsorbed at the renal corpuscle.

Question 65

A person lacking vasopressin would have to drink 180 L of water per day to make up for the water lost in the urine.

Question 66

The three basic processes of kidney function are filtration from the glomerulus into Bowman's capsule,secretion from the tubule into the peritubular capillaries,and reabsorption from the capillaries into the tubular lumen.

Question 67

Large amounts of protein in a person's urine indicate that the person is eating a high-protein diet.

Question 68

A consequence of lack of vasopressin is excretion of sugar in the urine,which occurs in the condition diabetes mellitus.

Question 69

Most of the body's water is located inside cells,whereas most of the body's Na⁺ is in the interstitial fluid and plasma.

Question 70

The kidneys regulate the plasma concentrations of water,sodium,and glucose.

Question 71

Water,sodium,and glucose all undergo tubular reabsorption,but urea does not.

Question 72

The total solute concentration in the extracellular fluid is mainly dependent upon the concentration of Na⁺ in the extracellular fluid.

Question 73

The anatomic arrangement of juxtamedullary nephrons in the kidneys is such that the glomerulus,proximal tubule,and distal convoluted tubule are in the renal cortex,while the loop of Henle and collecting ducts lie mainly in the renal medulla.

Question 74

The walls of the ascending limb of the loop of Henle are freely permeable to water.

Question 75

Voluntary control of micturition involves controlling somatic motor input to the muscles of the external urethral sphincter.

Question 76

Only substances that are filtered by the kidneys can be excreted by them.

Question 77

The filtered load of water in an average person is approximately 180 L/day.

Question 78

Water absorption from the proximal tubule is mainly driven by the active reabsorption of Na⁺.

Question 79

In healthy individuals,the amount of glucose present in urine will be virtually zero because the amount of glucose reabsorption from the filtrate back into the blood prevents excretion.

Question 80

The spinal reflex for micturition involves stretch receptors in the wall of the bladder that send messages about distension to sympathetic,parasympathetic,and motor neurons in the spinal cord.