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Chapter 27 Flashcards

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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
what is renal clearance
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)
26
clearance of substance is equal to
concentration of substance in urine x urine flow rate/ concentration of substance in plasma
27
what is more informative of function of kidneys than looking at composition of urine
measuring how effectively the kidneys are clearing
28
what is inulin
plant polysaccharide that is freely filtered and not reabsorbed, secreted or metabolized
29
iohexol clearance test
by measuring the plasma or serum disappearance of iodine follwoing IV dose of iohexol, GFRr can be estimated
30
RPF is equal to
PAH
31
Inulin
=GFR
32
Glucose
33
PAH
>GFR
34
URrea
35
H
>GFR
36
creatinine
=GFR
37
effect of reducing GFR by 50% on serum creatinine
serum creatinine increases, then levels off
38
a fall in GFR is followed by
an increase in plasma creatinine
39
the proximal tubules reabsorb about ______ of filtered _______
65%; sodium, chloride, bicarbonate, and potassium
40
proximal tubules reabsorb approximately all
filtered glucose and amino acids
41
the proximal tubules secrete ___________-
organic acids, bases, and hydrogen ions
42
review solute reasborption coupled to sodium
x
43
Na uptake into the cell of a proximal tubule is coupled with
either H or organic solutes like glucose, amion acids, P and lactate
44
Na-H antiporter
couples Na entry with H extursion
45
what is the source of the Hh
from carbonic anhydrase reaction
46
The H secretion results in absorption of
NaHCO3
47
Na-glucose symporter
Na and glucose enter cell together; glucose leave via glucose transporter on basolateral surface (GLUT)
48
Proximal tubule reabsorption is ______
isoosmotic
49
what is fanconi's syndrome
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)
50
fanconi's syndrome can be mimicked by
toxins and drugs that affect the proximal tubule and interrupt normal reabsorbtive functioning
51
_______ are secreted into PT
organic anions and cations
52
this includes what?
end products of metabolism and xenobiotics
53
secretion of these is important for what
removal of toxins and drugs
54
many organic compounds are protein bound. Why is this significant?
it means filtration alone will only remove a small proportion
55
the specificity of the transport mechanisms of organic anions and organic cations is _____
low
56
why is this significant
because compounds can compete for the same secretory pathway
57
competition for transport mechanisms between two cations or two anions can lead to what
drug toxicity
58
what is the only part of loop permeable to water
descending thin loop
59
drugs are _____ because they are not really filtered
actively secreted
60
because they are actively secreted, what occurs
must use a transporter
61
specifity for transports is
very low
62
descending thin segment of the loop of Henle permeability
highly permeable to water and moderately permeable to most solutes
63
mitochondria of descending thin loop
few mitochondria and little or no active reabsorption
64
thick ascending limb of the loop of henle reabsorbs about _____ of the filtered loads of ___________
25; sodium, chloride, and potassium, large amounts of Ca, bicarbonate, and Mg
65
what transporters/channels are present in the thick ascending limb
``` Na-K-Cl symporter (apical) K channel (apical) Na-H antiporter (apical) Vvoltage Na-K ATPase (basilateral) ```
66
Na-K-Cl symporter (apical)
Na and Cl gradient is to drive K into cell (against its concentration gradient)
67
K channel
recycles the K back into tubular fluid to drive the Na-K-Cl symporter
68
Na-H antiporter
Na reabsorption and H absorption
69
Voltage
positive charge in tubular fluid drives cation reabsorption
70
Na-K ATPase
Maintains low Na in cell thus providing a favorable gradient for Na entry
71
The loop reaborbs ______ of filtered NaCl
25%
72
the loop reabsorbs _____ of filtered water
20%
73
does the descending thin limb reabsorb NaCl
No because the gradient not favorable, no active transport
74
ascending thin limp functions in
passive reabsorption of NaCl (concentration gradient)
75
Thick ascending limb functions in
NaCl reabsorption by transcellular and paracellular pathways
76
the acending limb is referred to as the ______ segment
diluting
77
what is the net result at the end of the descending limb
[NaCl] increase in tubule fluid
78
why is the fluid in the ascending thin limb passive reabsorbed
the fluid delivered has increased [NaCl] and thus there is a gradient
79
what is the net result at end of ascending limb
[NaCl] decreases in tubule fluid- a "dilution effect"
80
what occurs in the distal tubule
dilutes or concentrates urine (fine adjustments to urine; where hormones take effect)
81
reabsorption of Na adn Cl occurs ____ in distal tubule
early
82
principal cells and ntercalated cells are in the _____
late distal tubule
83
Late DT is grouped with
collecting duct
84
what transports are in the early distal tubule?
Na-Cl cotransporter (apical) Na-K ATPase (basolateral) Cl Channel (basolateral)
85
Net osmotic effect of early distal tubule
continued dilution of urine
86
Na-Cl contransporter
Na and chloride entry
87
Na-K ATPase
Na leaves the cell
88
Cl channel
Cl leaves cell
89
Principal cells
reabsorb Na, Cl, and water; secrete K
90
Intercalated cells
Secrete H; Reabsorb K
91
permeability of late DT and CD to water is controlled by the concentration of
ADH
92
TOPICS OF COLLECTING DUCT
Fig. 27-11, 12, 10 | Fig 27-13
93
Principal cells are the site of action of _____
aldosterone
94
late DT and CD is impermeable to ____
urea
95
water reabsorption controlled by
ADH concentrations
96
principal cells contain what
Na-K ATPase Na channel K channel Water reabsorption
97
Na-K ATPase in principal cells
Keeps [Na] in cell low to facilitate entry of Na Na reabsorption K entry into cell
98
Na channel (principal cells)
Na entry into cell creates negative charge in tubular fluid
99
K channel (principal cells)
passive diffusion through channel from high [K] in cell to low [K] in tubular fluid
100
Water reasportion in principal cells
varies depending on ADH
101
Function of medullary collecting duct
NaCl Reabsorption Permeable to Urea Water Reabsorption, Controlled by ADH concentrations
102
study tables
4 of them
103
solute and water reabsorbed across _____
apical membrane
104
flow into interstitial space then into ____
capillary
105
some solute and water re-enter the _____
tubular fluid
106
proximal tubular and peritubular capillary reabsorption are affected by
peritubular capillary hydrostatic pressure or peritubular capillary colloid osmotic pressure (see chart)
107
knwo factors that can influence peritubular capillary reabsorption
x
108
aldosterone site of action
late DT and CD
109
Aldosterone effects
increase NaCl, H2O reabsorption, Increased K secretion (aldosterone can change K without changing Na and water, and vice versa)
110
agiotensin II site of action
PT, TAL, Late DT, and CD
111
Angiotensin II effects
Increased NaCl, H20 reabsorption
112
ADH site of action
late DT and CD
113
ADH effects
increased water reabsorption
114
atrial natriuretic hormone site of action
late DT and CD
115
atrial natriuretic hormone effects
decreased NaCl reabsorption
116
what are the stimuli for release of these hormones
renin, angiotensin, aldosterone
117
direct effects of angiotensin II to increase proximal tubular sodium reabsorption
see figure
118
what is the mechanism of ADHh
aquaporins are inserted on the apical side
119
Changes in GFR markedly alter the filtered load of ____
Na
120
what 2 mechanisms counter these changes so that there isnt a marked repsonse in Na excretion, which could disturb ECFV and blood pressure
1. starling forces in the PT | 2. filtred load of organic solutes
121
starling forces in the PTt
colloid oncotic pressure in peritubular capillary will increase with increased filtration fraction, thereby promoting greater reabsorption in the PT
122
filtered load of organic solutes
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
_________ corrects GFR to also guard against too much Na excretion
tubuloglomerular feedback
124
_____ can be differentially absorbed (Ch. 30)
Na and Cl
125
what is the primary mechanism in renal regulation of acid-base balance
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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