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Physiology > Chapter 27 > Flashcards

Chapter 27 Flashcards

1
Q

reabsorption is quantitatively ____

A

large

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2
Q

reabsorption is _____

A

selective

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3
Q

controlling reabsorption allows kidneys to regulate what

A

excretion of various solutes independently from one another

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4
Q

for a substance to be reabsorbed, what are the steps (what must be crossed to transport it?)

A

x

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5
Q

transcellular transport includes

A

diffusion and active transport

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6
Q

paracellular transport includes

A

diffusion

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7
Q

water moves by

A

osmosis

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8
Q

describe the steps of active transport of sodium

A
  1. Na enters cell due to electrochemical gradient
  2. Na transported out of cell (against the gradient) by Na-K atpase
  3. reabsorption completed withmovement from interstitial fluid into peritubular capillary
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9
Q

reabsorption of Na is governed by

A

hydrostatic and colloid osmotic pressure gradients

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10
Q

what helps keep the Na concentration

A

Nna-K ATPase

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11
Q

the amount of protein in filtrate is ____

A

low

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12
Q

why is it important for proteins to be reabsorbed?

A

because this low amount that is filtered adds up to a significant amount

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13
Q

what is the mechanism of protein reabsorption

A

pinocytosis; requires energy so this is active transport
once the proteins are inside the cell, cytosolic enzymes break them down into amino acids, the amino acids leave the cell via transporters and are returned to the blood

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14
Q

protein reabsorption mechanism: can it be saturated?

A

yes, in pathologic diseases you can have proteinuria

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15
Q

actively reabsorbed substances exhibit what

A

transport (tubular) maximum Tm

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16
Q

why is there an upper limit on how much of a particular substance can be actively transported from the tubular fluid in a given period of time

A

because a limited number of each carrier type is present in the cells lining the tubules

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17
Q

what is the transport maximum

A

when all the carriers specific for a particular substance are fully occupied

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18
Q

what is the renal threshold

A

the plasma concentration at which Ttm is reached and the substance starts to appear in the urine

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19
Q

what is the Tm of glucose

A

375 mg/min

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20
Q

what is the renal threshold for glucose

A

200-300 mg/dl

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21
Q

is glucose regulated by the kidney

A

the kidney does not maintain the plasma glucose in a specific range; not insulin dependent

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22
Q

how is this different from the Ph?

A

Ph is regulated by the kidney so Ph doesnt have to go over normal plasma concentration by much to have Ph excreted

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23
Q

what is the based law of conservation of mass

A

for any substance that is not synthesized or metabolized, the amount that enters the kidney in renal arterial blood is equal to the amount that leaves the kidney in renal venous blood plus urine

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24
Q

concentration =

A

mass/volume

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25
Q

what is renal clearance

A

the plasma clearance of any substance is defined as the volume of plasma completely cleared of that substance by the kidneys per minute (volume/minute)

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26
Q

clearance of substance is equal to

A

concentration of substance in urine x urine flow rate/ concentration of substance in plasma

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27
Q

what is more informative of function of kidneys than looking at composition of urine

A

measuring how effectively the kidneys are clearing

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28
Q

what is inulin

A

plant polysaccharide that is freely filtered and not reabsorbed, secreted or metabolized

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29
Q

iohexol clearance test

A

by measuring the plasma or serum disappearance of iodine follwoing IV dose of iohexol, GFRr can be estimated

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30
Q

RPF is equal to

A

PAH

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31
Q

Inulin

A

=GFR

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32
Q

Glucose

A

<GFR

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33
Q

PAH

A

> GFR

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34
Q

URrea

A

<GFR

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35
Q

H

A

> GFR

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36
Q

creatinine

A

=GFR

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37
Q

effect of reducing GFR by 50% on serum creatinine

A

serum creatinine increases, then levels off

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38
Q

a fall in GFR is followed by

A

an increase in plasma creatinine

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39
Q

the proximal tubules reabsorb about ______ of filtered _______

A

65%; sodium, chloride, bicarbonate, and potassium

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40
Q

proximal tubules reabsorb approximately all

A

filtered glucose and amino acids

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41
Q

the proximal tubules secrete ___________-

A

organic acids, bases, and hydrogen ions

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42
Q

review solute reasborption coupled to sodium

A

x

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43
Q

Na uptake into the cell of a proximal tubule is coupled with

A

either H or organic solutes like glucose, amion acids, P and lactate

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44
Q

Na-H antiporter

A

couples Na entry with H extursion

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45
Q

what is the source of the Hh

A

from carbonic anhydrase reaction

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46
Q

The H secretion results in absorption of

A

NaHCO3

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47
Q

Na-glucose symporter

A

Na and glucose enter cell together; glucose leave via glucose transporter on basolateral surface (GLUT)

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48
Q

Proximal tubule reabsorption is ______

A

isoosmotic

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49
Q

what is fanconi’s syndrome

A

an inherited disease that affects the proximal renal tubule (impaired Na, glucose, Ca, P, HCO3, and AA reabsorption; increased amount of solutes in the urine causes osmotic diuresis and inability to concentrate urine)

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50
Q

fanconi’s syndrome can be mimicked by

A

toxins and drugs that affect the proximal tubule and interrupt normal reabsorbtive functioning

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51
Q

_______ are secreted into PT

A

organic anions and cations

52
Q

this includes what?

A

end products of metabolism and xenobiotics

53
Q

secretion of these is important for what

A

removal of toxins and drugs

54
Q

many organic compounds are protein bound. Why is this significant?

A

it means filtration alone will only remove a small proportion

55
Q

the specificity of the transport mechanisms of organic anions and organic cations is _____

A

low

56
Q

why is this significant

A

because compounds can compete for the same secretory pathway

57
Q

competition for transport mechanisms between two cations or two anions can lead to what

A

drug toxicity

58
Q

what is the only part of loop permeable to water

A

descending thin loop

59
Q

drugs are _____ because they are not really filtered

A

actively secreted

60
Q

because they are actively secreted, what occurs

A

must use a transporter

61
Q

specifity for transports is

A

very low

62
Q

descending thin segment of the loop of Henle permeability

A

highly permeable to water and moderately permeable to most solutes

63
Q

mitochondria of descending thin loop

A

few mitochondria and little or no active reabsorption

64
Q

thick ascending limb of the loop of henle reabsorbs about _____ of the filtered loads of ___________

A

25; sodium, chloride, and potassium, large amounts of Ca, bicarbonate, and Mg

65
Q

what transporters/channels are present in the thick ascending limb

A 
Na-K-Cl symporter (apical)
K channel (apical)
Na-H antiporter (apical)
Vvoltage
Na-K ATPase (basilateral)
66
Q

Na-K-Cl symporter (apical)

A

Na and Cl gradient is to drive K into cell (against its concentration gradient)

67
Q

K channel

A

recycles the K back into tubular fluid to drive the Na-K-Cl symporter

68
Q

Na-H antiporter

A

Na reabsorption and H absorption

69
Q

Voltage

A

positive charge in tubular fluid drives cation reabsorption

70
Q

Na-K ATPase

A

Maintains low Na in cell thus providing a favorable gradient for Na entry

71
Q

The loop reaborbs ______ of filtered NaCl

A

25%

72
Q

the loop reabsorbs _____ of filtered water

A

20%

73
Q

does the descending thin limb reabsorb NaCl

A

No because the gradient not favorable, no active transport

74
Q

ascending thin limp functions in

A

passive reabsorption of NaCl (concentration gradient)

75
Q

Thick ascending limb functions in

A

NaCl reabsorption by transcellular and paracellular pathways

76
Q

the acending limb is referred to as the ______ segment

A

diluting

77
Q

what is the net result at the end of the descending limb

A

[NaCl] increase in tubule fluid

78
Q

why is the fluid in the ascending thin limb passive reabsorbed

A

the fluid delivered has increased [NaCl] and thus there is a gradient

79
Q

what is the net result at end of ascending limb

A

[NaCl] decreases in tubule fluid- a “dilution effect”

80
Q

what occurs in the distal tubule

A

dilutes or concentrates urine (fine adjustments to urine; where hormones take effect)

81
Q

reabsorption of Na adn Cl occurs ____ in distal tubule

A

early

82
Q

principal cells and ntercalated cells are in the _____

A

late distal tubule

83
Q

Late DT is grouped with

A

collecting duct

84
Q

what transports are in the early distal tubule?

A

Na-Cl cotransporter (apical)
Na-K ATPase (basolateral)
Cl Channel (basolateral)

85
Q

Net osmotic effect of early distal tubule

A

continued dilution of urine

86
Q

Na-Cl contransporter

A

Na and chloride entry

87
Q

Na-K ATPase

A

Na leaves the cell

88
Q

Cl channel

A

Cl leaves cell

89
Q

Principal cells

A

reabsorb Na, Cl, and water; secrete K

90
Q

Intercalated cells

A

Secrete H; Reabsorb K

91
Q

permeability of late DT and CD to water is controlled by the concentration of

A

ADH

92
Q

TOPICS OF COLLECTING DUCT

A

Fig. 27-11, 12, 10

Fig 27-13

93
Q

Principal cells are the site of action of _____

A

aldosterone

94
Q

late DT and CD is impermeable to ____

A

urea

95
Q

water reabsorption controlled by

A

ADH concentrations

96
Q

principal cells contain what

A

Na-K ATPase
Na channel
K channel
Water reabsorption

97
Q

Na-K ATPase in principal cells

A

Keeps [Na] in cell low to facilitate entry of Na
Na reabsorption
K entry into cell

98
Q

Na channel (principal cells)

A

Na entry into cell creates negative charge in tubular fluid

99
Q

K channel (principal cells)

A

passive diffusion through channel from high [K] in cell to low [K] in tubular fluid

100
Q

Water reasportion in principal cells

A

varies depending on ADH

101
Q

Function of medullary collecting duct

A

NaCl Reabsorption
Permeable to Urea
Water Reabsorption, Controlled by ADH concentrations

102
Q

study tables

A

4 of them

103
Q

solute and water reabsorbed across _____

A

apical membrane

104
Q

flow into interstitial space then into ____

A

capillary

105
Q

some solute and water re-enter the _____

A

tubular fluid

106
Q

proximal tubular and peritubular capillary reabsorption are affected by

A

peritubular capillary hydrostatic pressure or peritubular capillary colloid osmotic pressure (see chart)

107
Q

knwo factors that can influence peritubular capillary reabsorption

A

x

108
Q

aldosterone site of action

A

late DT and CD

109
Q

Aldosterone effects

A

increase NaCl, H2O reabsorption, Increased K secretion (aldosterone can change K without changing Na and water, and vice versa)

110
Q

agiotensin II site of action

A

PT, TAL, Late DT, and CD

111
Q

Angiotensin II effects

A

Increased NaCl, H20 reabsorption

112
Q

ADH site of action

A

late DT and CD

113
Q

ADH effects

A

increased water reabsorption

114
Q

atrial natriuretic hormone site of action

A

late DT and CD

115
Q

atrial natriuretic hormone effects

A

decreased NaCl reabsorption

116
Q

what are the stimuli for release of these hormones

A

renin, angiotensin, aldosterone

117
Q

direct effects of angiotensin II to increase proximal tubular sodium reabsorption

A

see figure

118
Q

what is the mechanism of ADHh

A

aquaporins are inserted on the apical side

119
Q

Changes in GFR markedly alter the filtered load of ____

A

Na

120
Q

what 2 mechanisms counter these changes so that there isnt a marked repsonse in Na excretion, which could disturb ECFV and blood pressure

A
  1. starling forces in the PT

2. filtred load of organic solutes

121
Q

starling forces in the PTt

A

colloid oncotic pressure in peritubular capillary will increase with increased filtration fraction, thereby promoting greater reabsorption in the PT

122
Q

filtered load of organic solutes

A

filtered load of organic solutes (like glucose and amino acids) will also increase with increased filtration fraction; since Na reabsorption is coupled to their reabsorption in PT, it promotes reabsorption of Na

123
Q

_________ corrects GFR to also guard against too much Na excretion

A

tubuloglomerular feedback

124
Q

_____ can be differentially absorbed (Ch. 30)

A

Na and Cl

125
Q

what is the primary mechanism in renal regulation of acid-base balance

A

Net Cl excretion relative to net Na excretion; since sodium reabsorption is strongly related to renal regulation of ECFV

Physiology (4 decks)

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