Renal Reabsorption Flashcards

1
Q

Where does filtration take place?

A

Bowmans capsule

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2
Q

Only about _____ liters of the 150-200 liters of filtrate is excreted as urine, the rest (~ 99%) is reabsorbed into the blood.

A

1 - 2

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3
Q

Nephrons must reabsorb ~ _____% of the filtrate

A

99

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4
Q

The proximal convoluted tubule (PCT) reabsorbs ______% of most filtered substances

A

50-100

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5
Q

The proximal convoluted tubule (PCT) reabsorbs:

A

Nutritionally important molecules
Solutes by active & passive processes
water by osmosis
small proteins by digestion and/or pinocytosis

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6
Q

________ Transport across the kidney tubule occurs mainly via a variety of channels and transport proteins in the renal tubule cell plasma membranes

A

Transcellular Transport

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7
Q

Transcellular transport proteins are often exclusively localized to either the _____ or the _____ surface of the tubule cell

A

apical

basolateral

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8
Q

________ Transport may also occur across the tight junctions between the tubule cells

A

Paracellular

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9
Q

Paracellular transport will be influenced by the permeability of the _____ _____, limited surface area and the electrical and chemical gradients across the tubule (filtrate versus extracellular fluid)

A

tight junctions

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10
Q

Where does most Na+ reabsorption take place?

A

PCT

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11
Q
Sodium Reabsorption in:
PCT
Ascending Loop
DCT
Principle cells of late distal tubule and collecting duct
A

65%
20-30%
5%
1-4%

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12
Q

Principle cells of the late DCT & collecting duct: ~1-4% Na+ reabsorbed (stimulated by ________)

A

aldosterone (increases blood pressure by increasing water reabsorption)

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13
Q

Aldosterone acts on the cells of the ____ nephron.

A

distal

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14
Q

Na+ / K+ ATPase pump is localized to the _____ membrane of the nephron epithelial cells

A

basolateral

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15
Q

Sodium-dependent Secondary Active Transport:

Symport Carriers

A
Na-glucose (SGLUT & SGLUT1)
NA-Amino Acids
Na-K-@Cl
Na-Cl
Na-HCO3-
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16
Q

Sodium-dependent Secondary Active Transport:

Antiport Carriers

A

Na+-H+ (proximal tubules)

Na+-Ca++

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17
Q

The _____ _______ group of membrane transport proteins has over 300 members organized into 47 families and includes a variety of facilitative transporters and secondary active transporters

A

Solute Carrier (SLC)

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18
Q

Solute Carrier series does not include members of transport protein families which have previously been classified by other widely accepted nomenclature systems including:

A

primary active transporters such as ABC (ATP Binding Cassette) transporters
ion channels
aquaporins (water channels)

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19
Q

high H+; low pH

A

Acidosis

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20
Q

low H+; high pH

A

Alkalosis

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21
Q

high Na+

A

Hypernatremia

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22
Q

low Na+

A

Hyponatremia

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23
Q

high K+

A

Hyperkalemia

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24
Q

low K+

A

Hypokalemia

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25
Q

an elevated blood level of the electrolyte sodium usually caused by lack of water (dehydration) or ingestion of massive amounts of salt

A

Hypernatremia

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26
Q

Hypernatremia symptoms

A

lethargy, weakness, irritability, and edema

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27
Q

severe elevations of sodium may cause:

A

seizures, coma and death

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28
Q

hypernatremia may be caused by drugs with _______ activity (______)

A

mineralocorticoid (cortisol)

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29
Q

a decreased blood level of the electrolyte sodium

A

Hyponatremia

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30
Q

Symptoms of hyponatremia include:

A

nausea and vomiting, headache, confusion, lethargy, fatigue, appetite loss, restlessness and irritability, muscle weakness, spasms, or cramps, seizures, decreased consciousness, coma and death

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31
Q

can be caused by excessive water intake or inadequate sodium intake

A

Hyponatremia

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32
Q

Some medications can accelerate the removal of sodium from the body or increase water retention (hyponatremia):

A

thiazide diuretics, selective serotonin reuptake inhibitors and some pain medications (accelerate removal of sodium)

desmopressin, MDMA (increase water retention)

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33
Q

Where does most K+ reabsorption take place?

A

PCT

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34
Q

Potassium Reabsorption:
PCT
Ascending Loop
DCT and Collecting Duct

A

65%
~20-30%
variable K+ secretion depending on dietary intake

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35
Q

secretion in the DCT & collecting duct is stimulated by _____

A

aldosterone

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36
Q

is an elevated blood level of the electrolyte potassium

A

Hyperkalemia

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37
Q

Symptoms of hyperkalemia are fairly nonspecific and generally include malaise, muscle weakness, palpitations and electrocardiographic (ECG) changes such as:

A

reduction of the size of the P wave
development of peaked T waves
widening of the QRS complex

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38
Q

caused by excessive intake or ineffective elimination of potassium
Renal failure
Mineralocorticoid deficiency

A

Hyperkalemia

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39
Q

Medications that interferes with urinary excretion of potassium (hyperkalemia)

A
  • ACE inhibitors
  • angiotensin receptor blockers
  • Potassium-sparing diuretics (amiloride and spironolactone)
  • NSAIDs such as: ibuprofen, naproxen, or celecoxib
  • calcineurin inhibitor immunosuppressants: (cyclosporin and tacrolimus)
  • antibiotics (trimethoprim)
  • antiparasitic drugs (pentamidine)
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40
Q

often without symptoms, although it may cause a small elevation of blood pressure and can occasionally provoke cardiac arrhythmias; K+ level >3.0 mEq/L

A

Mild hypokalemia

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41
Q

may cause muscular weakness, myalgia, muscle cramps, and constipation; K+ level of 2.5-3 mEq/L

A

Moderate hypokalemia

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42
Q

usually caused by excessive loss of potassium, often associated with vomiting, diarrhea, or excessive perspiration

A

Hypokalemia

43
Q

Some medications can accelerate the removal of potassium from the body, including (hypokalemia)

A

thiazide diuretics, such as hydrochlorothiazide, loop diuretics such as furosemide,
laxatives,
antifungal amphotericin B

44
Q

Where does most Cl- reabsorption take place?

A

PCT

45
Q
Chloride Reabsorption;
PCT
Ascending Loop
DCT
Principle cells of late DCT and Collecting Duct
A

50%
35%
5%
1-4%

46
Q

Loop (ascending limb)reabsorbs ~35% Cl- via ________________

A

Na-K-Cl cotransporter

47
Q

DCT reabsorbs ~5% Cl- via ___________

A

sodium-chloride symporter

48
Q

a membrane transport protein that aides in the active cotransport of 1 sodium, 1 potassium, and 2 chloride ions.

A

The Na-K-Cl cotransporter

49
Q

There are two isoforms of Na-K-Cl cotransporter:

A

NKCC1

NKCC2

50
Q

NKCC1 [Ch5q15-21.1] is widely distributed throughout the body, especially organs that ______fluids

A

secrete

51
Q

NKCC2 [Ch5q23.3] is found specifically in the kidney ______ loop

A

ascending

52
Q

Na-K-Cl cotransporter is inhibited by _________ & ________

A

furosamide & bumetanide (loop diuretics)

53
Q

a symporter ion pump used primarily to remove sodium and chloride ions from the filtrate in the distal convoluted tubule of the kidney

A

sodium-chloride symporter

54
Q

sodium-chloride symporter is inhibited by:

A

thiazide diuretics

55
Q

Where does most water reabsorption take place?

A

PCT

56
Q

_____ is reabsorbed by osmosis and mostly follows sodium

A

Water

57
Q
Water Reabsorption:
PCT
Descending limb 
DCT
Late DCT and Collecting Duct
A

65%
15%
10-15%
5-10%

58
Q

Water reabsorption through the late DCT and collecting duct is stimulated by _____. The reabsorption with Na and Cl is stimulated by _______

A

ADH

Aldosterone

59
Q

There are ____ Aquaporins in Mammalian Systems

A

10

60
Q

_____ Aquaporins in Biological Systems

A

> 200

61
Q

AQP 1 is found in: 5

A
RBC
Proximal Tubule
Descending loop 
Brain Astrocytes
Supporting cells of Ear
62
Q

_____ stimulates an increase in water permeability in the renal epithelial cells of the distal tubule & collecting ducts

A

Vasopressin

63
Q

water channels
inserted into the
apical membrane

A

Aquaporin 2

64
Q

____ hydrostatic pressure and ___ oncotic pressure in peritubular capillaries favors water reabsorption

A

Low

high

65
Q

movement of molecules OUT of the tubule filtrate and INTO the peritubular capillary blood

A

Reabsorption

66
Q

Proximal tubule apical membrane has increased surface area (_____) which facilitates rapid reabsorption and increased surface area of _____ membrane with mitochondria to produce ATP for active transport

A

microvilli

basal

67
Q

_________ _________ important for reabsorption of bicarbonate and secretion of hydrogen ions. This is a diuretic action of ________ ___________ inhibitors

A

Carbonic anhydrase

Carbonic anhydrase

68
Q

The proximal convoluted tubule reabsorbs nearly 100% of most nutritionally important molecules such as glucose, amino acids, lactate, succinate, citrate and others via _______ with sodium ions

A

symport

69
Q

Glucose is reabsorbed in the proximal convoluted tubule by _____ ______ ______ carriers coupled to Na+

A

secondary active transport

70
Q

Transporters can become ________

When transporters reach their maximum transport ability (Tm) no more glucose is reabsorbed

A

saturated

71
Q

Glucose concentration in plasma < ___ mg in 100 ml of plasma. Therefore, glucose concentration delivered to the tubules is: ~_____ mg/ min

A

100

90-110

72
Q

Transport maximum for glucose = Tm = ~___ mg/min

A

375

73
Q

Glucose starts to appear in the urine when plasma concentration is ~____mg/dL

A

150-200

74
Q

Renal symporters can not reabsorb glucose fast enough if blood glucose level is above ___ mg/mL.
Some glucose remains in the urine (________)

A

200

glucosuria

75
Q

Osmotic action of glucose in the ____ nephron causes an osmotic diuresis (glucosuria)

A

distal

76
Q

Common cause of glucosuria is _______ _______ because insulin activity is deficient and blood sugar is too high
genetic disorder produces defect in _____ that reduces its effectiveness

A

diabetes mellitis

symporter

77
Q

Na+-K+ ATPase Pump is located in the _______ membrane. Sodium-Glucose Cotransporter (SGLT-2)
is located on the _____ membrane

A

basolateral

apical

78
Q

Glucose can be transported ______ (SGLUT), or by _____ diffusion (GLUT)

A

actively

facilitated

79
Q

glucose requires ______ transport

A

mediated

80
Q

secondary active transport proteins in the membrane of the apical surface

A

SGLT 1

SGLT 2

81
Q

responsible for 2% of renal glucose reabsorption and most of intestinal glucose/galactose absorption; on S3 of PCT and intestinal mucosa

A

SGLT 1

82
Q

responsible for 98% of renal glucose reabsorption; in S1 and S2 of PCT

A

SGLT 2

83
Q

drug used for treatment of type 2 diabetes in adults

The drug is a sodium glucose co-transporter 2 (SGLT2) inhibitor “that blocks the reabsorption of glucose by the kidney, increases glucose excretion, and lowers blood glucose levels”

A

Dapagliflozin (Farxiga)

84
Q

SGLT-2 inhibitors, which blocks the reabsorption of glucose by the kidney increasing glucose excretion, and lowering blood glucose levels

A

Canagliflozin (Invokana)

Dapagliflozin (Farxiga)

85
Q

Glucose Transporter Proteins facilitated diffusion

A
GLUT 1
GLUT 2
GLUT 3
GLUT 4
GLUT 5
86
Q

Broad expression; has high affinity for glucose (not fructose)
in basolateral membrane

A

GLUT 1

87
Q

Low affinity for glucose; high capacity transporter (sensor in pancreas)
in basolateral membrane

A

GLUT 2

88
Q

glucose transporters in the apical membrane are (secondary active transport)

A

SGLUT 1 and SGLUT 2

89
Q

glucose transporters in the basolateral membrane are

facilitated diffusion

A

GLUT 1 and GLUT 2

90
Q

___ is located in the basolateral membrane of the EARLY proximal tubule cell

A

GLUT1

91
Q

___ is located on the basolateral membrane of the LATE proximal tubule cell

A

GLUT2

92
Q

______ is in the apical membrane of the early proximal tubule cell, _____ is in the apical membrane of the Late proximal tubule cell

A

SGLUT 2, SGLUT 1

93
Q

Filtered HCO3 is titrated by secreted ___ to CO2 and water

A

protons

94
Q

hydration of CO2 in the cell produces protons for secretion and ____, which is transported by _____ cotransporter in a ratio of 3 ___:___Na. Thus one ___ disappears from tubular fluid and another appears in ISF

A

HCO3-
Na-HCO3
HCO3-1Na
HCO3

95
Q

a protein (enzyme) in erythrocytes and kidney tubule cells that catalyses the reversible conversion of carbon dioxide and water to carbonic acid

A

Carbonic anhydrase

96
Q

A carbonic anhydrase inhibitor

Used to treat some types of glaucoma and conditions of moderate to severe metabolic alkalosis

may be used as a diuretic

will produce bicarbonaturia and type 2 renal tubular acidosis

A

Acetazolamide

97
Q

The appearance of protein in the urine (_______) indicates renal pathology

A

proteinuria

98
Q

Proteases and peptidases on the apical membrane of the proximal tubule hydrolyze proteins into amino acids that are reabsorbed by

A

Na+-amino acid transporters (symporters)

99
Q

Some protein is also taken up by ____ and receptor mediated ______ for digestion by lysosomes or transcellular transport to the basal ECF

A

pinocytosis

endocytosis

100
Q

Where do thiazide diuretics inhibit reabsorption

A

DCT

101
Q

What protein does thiazide diuretics inhibit?

A

Na/Cl symporter

102
Q

Where does furosemide inhibit reabsorption?

A

Thick ascending limb of Loop

103
Q

What protein does furosemide inhibit?

A

Na/K/2Cl cotransporter