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OLD "MBS 603" > Exam 4 Part 2 > Flashcards

Exam 4 Part 2 Flashcards

1
Q

What are the 2 main functions of the loop of Henle?

A

reabsorbs H2O then reabsorbsNaCl

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2
Q

The end goal of the Loop of Henle is create a _____tonic tubule fluid

A

hypotonic

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3
Q

What is the main action of the thin descending limb?

A

H2O reabsorption

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4
Q

Does NaCl reabsorption occur in the thin descending limb?

A

no

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5
Q

Fluid movement down the thin descending limb become more ___________

A

concentrated (hyperosmotic)

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6
Q

What is the main action of the thin ascending limb/thick ascending?

A

NaCl reabsorption

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7
Q

Does H2O reabsorption occur in the thin acsending limb/thick ascending?

A

no

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8
Q

Fluid movement up the thin ascending limb/thick ascending limb become more ___________

A

diluted (hyposmotic)

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9
Q

How does reabsorption of NaCl through the thin ascending limb occur?

A

passivley

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10
Q

How does reabsorption of NaCl through the thick ascending limb occur?

A

active transport

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11
Q

What active transporter reabsorbs NaCl out of the thick ascending limb?

A

Na/K/2Cl co-transporter

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12
Q

What is the Vte in the thick ascending limb?

A

+10

very positive

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13
Q

What makes the Vte so positive in the thick ascending limb?

A

abundance of apical K+ channel that stimualtes paracellular transport of K+ into tubule lumen

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14
Q

What is Bartter Syndrome?

A

defective Na/K/Cl cotransporter (thick ascending limb) causing less K+ movement = less positive Vte = slows ion reabsorption

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15
Q

What happens to the Vte if the Na/K/Cl cotransporter in the thick ascending limb is non-functional?

A

less K+ movement = less positive Vte = slows ion reabsorption

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16
Q

What are loop diuretics?

A

inhibit Na/K/Cl cotransporter (in thick ascending limb)

reduces NaCl reabsorption by preventing K+ for keeping lumen positive

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17
Q

What is the importance of K+ in the thick ascending limb?

A

keeps Vte positive to drive ion reabsorption

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18
Q

What ions are reabsorbed in the thick ascending limb?

A

Na+
Cl-
Ca2+
Mg2+

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19
Q

How is K+ reabsorbed in the thick ascending limb?

A

50% via Na/K/Cl cotransporter (transcellular)

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20
Q

How is Ca2+ reabsorbed in the thick ascending limb?

A

50% paracellular
50% transcellular

  • has its own ion channel, does not use Na/K/Cl cotransporter
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21
Q

What ion’s reabsorption dominates of Ca2+ through the paracellular route?

A

Mg2+

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22
Q

How is Mg2+ reabsorbed in the thick ascending limb?

A

paracellular diffusion

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23
Q

Where is most of the Mg2+ reabsorbed?

A

thick ascending limb (70%)

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24
Q

______________-1 is required for Mg2+ diffusion through tight junctions and is the reason for high Mg2+ in the TAL

A

paracellin-1

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25
Q

What are the 2 cell types in the distal tubule and collective duct?

A

alpha/beta-intercalated cells
principle cells

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26
Q

What is the importance of principle cells in the distal tubule?

A

Na+ reabsorption stimulated by aldosterone

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27
Q

What is special about the medullary collecting duct cells?

A

(end of nephron)
very tight to prevent reabsorption/leaking at the end

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28
Q

In the distal tubule, NaCl is reabsorbed transcellularly via what co-transporter?

A

thiazide sensitive NaCl cotransporter

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29
Q

What happens if the thiazide sensitive NaCl cotransporter in the distal tubule doesn’t work?

A

NaCl is not reabsorbed and urine is more concentrated

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30
Q

What is Gitelman syndrome?

A

defective thiazide sensitive NaCl cotransporter in the distal tubule (NaCl not reabsorbed)

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31
Q

What is the Vte of principle cells in the collect duct?

A

-40 mV
very negative

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32
Q

What is the transcellular transporter/channel that reabsorbs Na+ in principle cells of the collecting duct?

A

ENac

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33
Q

Why is the Vte of principle cells so negative?

A

ENac is pulling Na+ out of lumen

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34
Q

How does Cl- travel out of lumen in collecting duct in principle cells?

A

paracellularly

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35
Q

What it Liddle syndrome?

A

increased ENac activity (collecting duct) causing high BP
- increased reabsorption of NaCl

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36
Q

What is the Vte of beta-intercalated cells in the collecting duct?

A

-40 mV
very negative

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37
Q

Why is the Vte of beta-intercalated cells so negative in the collecting ducts?

A

HCO3- is being pumped into lumen

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38
Q

What transporter is used by beta-intercalated cells in collecting ducts to transport Cl-?

A

Cl-HCO3- exchanger

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39
Q

Do beta-intercalated cells in the collecting duct transport Na+?

A

no

only Cl-, HCO3, H+

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40
Q

What is special about the beta-intercalated in the collecting duct?

A

aid in acid base exchange
(HCO3 into the lumen and H+ reabsorbed)

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41
Q

What is aldosterone’s affect on NaCl reabsorption?

A

increases NaCl reabsorption

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42
Q

Do intercalated cells or principle cells in the collecting duct perform K+ secretion?

A

principle cells

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43
Q

What cells perform K+ reabsorption in DT and CD?

A

alpha-intercalated cells

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44
Q

Why does hypokalemia induce acidosis?

A

K+ reabsorption is mediated by lumen H/K pump where H+ is secreted

  • low K+ in blood = higher H+ in blood
  • alpha-intercalated cells
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45
Q

Do alpha or beta intercalated cells perform H+ secretion?

A

alpha

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46
Q

Do alpha or beta intercalated cells perform HCO3- secretion?

A

beta

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47
Q

What side is the HCO3- pump and the H+ pump located on alpha-intercalated cells?

A

HCO3-: basolateral
H+: apical

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48
Q

What side is the HCO3- pump and the H+ pump located on beta-intercalated cells?

A

HCO3-: apical
H+: basolateral

49
Q

Ca+ is reabsorbed in the proximal tubule but also in the …

A

distal (convoluted) tubule

50
Q

Ca+ reabsorption is tightly regulated in the __________ compared to the proximal tubule.

A

distal (convoluted) tubule

51
Q

What are volatile vs non-volatile acid?

A

volatile: blown off by lungs
non-volatile: builds up

52
Q

What are 3 ways to control pH plasma?

A

buffering system (CO2/HCO3, phosphate, ammonia)
lung system (CO2 levels)
kidney system (HCO3- levels, and execrating non-volatile acids)

53
Q

What are the 3 buffering system examples?

A

CO2/HCO3
phosphate
ammonia

54
Q

What is the job of a proton buffer?

A

minimize changes in pH

55
Q

The HCO3-/CO2 buffering system has a poor pK. Why is this ok?

A

CO2 can be blown off and HCO3 levels can be very high

56
Q

What are 2 reasons kidneys excrete H+ into the lumen of tubules?

A
  1. reabsorb filtered HCO3- (protons not excreted)
  2. excrete non-volatile acids (protons excreted)
57
Q

What’s the net uptake of acid in one day?

A

30

58
Q

What is the net amount of metabolic acid produced in one day?

A

55
(15 CO2; 40 non-volatile acid)

59
Q

How much H+ is excreted in one day?

A

70

60
Q

How much HCO3- is reabsorbed in one day?

A

4320

61
Q

What are 3 steps the body takes when a load of acid is introduced?

A
  1. plasma HCO3- immediately buffers H+
  2. CO2 generated from 1. is blown off
  3. new HCO3 forms in kidneys and replaces HCO3 used in 1.
62
Q

Draw the steps of HCO3 reabsorption?

A

slide 11

63
Q

Draw the steps of H+ excretion?

A

slide 11

64
Q

What are the 2 titratable acids?

A

H2PO4-
NH4

65
Q

What are the 2 fates of H+ secreted in the lumen?

A
  1. combined to make water to generate new HCO3
  2. excreted as titratable acids
66
Q

Is the HCO3 made in H+ excreted considered new or old?

A

new

67
Q

Is HCO3 made in HCO3 reabsorption considered new or old?

A

old

68
Q

Where is most of the HCO3 reabsorbed in the nephron?

A

proximal tubule

69
Q

Where is the other two 10% of HCO3 reabsorbed?

A

thick ascending limb
distal tubule

70
Q

The majority of new HCO3- is generated from H2PO4 or NH4?

A

NH4

71
Q

What 3 segments of the nephron participate in acid secretion?

A

proximal tubule
thick ascending limb
cortical collecting duct

72
Q

How does the proximal tubule play a role in acid secretion?

A

Cl/HCO3- exchanger (bicarbonate reabsorption)

73
Q

How does the thick ascending limb play a role in acid secretion?

A

Cl-/HCO3- exchanger (bicarbonate reabsorption)

74
Q

How does the cortical collecting duct play a role in acid secretion?

A

alpha and beta intercalated cells (bicarbonate reabsorption)

75
Q

What is the importance of glutamine breakdown and urea formation?

A

important for excretion amine groups

76
Q

What’s the difference between glutamine breakdown and urea formation?

A

glutamine breakdown: generates new HCO3
urea formation: looses HCO3

77
Q

Is urea formation or glutamine breakdown stimulated by acidosis?

A

glutamine breakdown
- forms new HCO3-

78
Q

Kidneys regulate plasma osmolality by regulating ______ osmolality

A

urine (creating a concentrated or dilute urine)

79
Q

Dilute urine is a result of reabsorption of _____

A

NaCl

80
Q

Concentrated urine is a result of reabsorption of _____

A

H2O

81
Q

To make a concentrated urine, what 2 things are needed?

A
  1. H2O permeable nephron segments
  2. hyper-osmotic medullary intersistum
82
Q

What is the role of ADH?

A

increases water reabsorption (more concentrated urine)

83
Q

How does ADH work?

A

binds to receptors on principle cells which causes more aquaporins to be inserted on apical side = more water reabsorption

84
Q

What are 2 stimulators of ADH?

A
  1. increased plasma osmolality
  2. decreased ECF
85
Q

What is the main stimulator of ADH?

A

increased plasma osmolality

86
Q

What are the 2 feedback loops used to return elevated plasma osmolality back to normal?

A
  1. increase thirst = increase water intake
  2. release ADH = increased water reabsorption
87
Q

What 2 segments of the nephron are the most water permiable?

A

proximal tubule
thin descending limb

88
Q

Where is ADH most active in the nephron?

A

inner medulla collecting duct

89
Q

Where in the nephron does ADH first appear?

A

distal tubule

90
Q

What are the 2 steps to generating a hypersmotic medullary interstitum?

A
  1. reabsorb H2O in thin descending loop
  2. reabsorb NaCl in tALH anf TAL
91
Q

Is the medullary intersistum hyperosmotic or hyposmotic at the end of the thin descending limb?

A

hypososmotic

92
Q

Is the medullary intersistum hyperosmotic or hyposmotic at the end of the thick ascending limb?

A

hyperosmotic

93
Q

Does tALH and TAL have water permiability?

A

no

94
Q

NaCl is actively or passively reabsorbed out of thin ascending limb?

A

passively

95
Q

NaCl is actively or passively reabsorbed out of thick ascending limb?

A

actively

96
Q

Reabsorption of NaCl by the ascending limb creates a gradient between the interstitum and the tubule lumen and is amplified by …

A

counter current loop

97
Q

The countercurrent multiplier loop causes a gradient that drives NaCl to the _______ of the nephron in the medulla

A

tip

98
Q

What is the single effect in the countercurrent multiplier loop?

A

movement of NaCl out of ascending limb which increases the osmolarity of interstitium

99
Q

What is the osmotic equillibrium in the countercurrent multiplier loop?

A

entering isosmotic fluid (from PT) is turned hyperosmotic b/c water is leaving lumen

100
Q

What is tubule flow countercurrent multiplier loop?

A

concentrated fluid moves to the tip of loop which drives more NaCl into intersistium (hyperosmotic interstitum)

101
Q

What are the 3 steps of the countercurrent multiplier loop?

A
  1. single effect
  2. osmotic equillibrium
  3. tubule flow
102
Q

What are 2 methods to prevent blood from picking up NaCl and washing it out of interstitum?

A
  1. vasta recta
  2. decrease blood flow
103
Q

What does the vasta recta do?

A

capillaries running parallel to LH that pick up salt but then deliver it back to intersistum

104
Q

Where are vasta recta capillaries located?

A

parallel to LH

105
Q

Urea concentration _________ as you get deeper in the medulla?

A

increases

106
Q

What secretes 50% of urea?

A

tip of loop of Henle

107
Q

Concentrated urea in the collecting duct is reabsorbed in the presence of _______

A

ADH

108
Q

decreased H2O intake = ________ ADH = ________ urea recycling = _______ urea build up in intersisitum = ________ interstitium osmolarity = ________ water reabsorption = __________ H2O excretion

A

increase ADH
increase urea recycling
increase build up
increase osm
increase reabsorption
decreased excretion

109
Q

If water intake decreases what happen to ADH levels?

A

increases

110
Q

If ADH increases urea will build up in interstitum, why?

A

driving force for water reabsorption to hydrate body

111
Q

Respiratory acidosis…
pH:
[HCO3-]:
PCO2:
equation:

A

pH: decrease
[HCO3-]: increase
PCO2: increase
equation: right

112
Q

Respiratory alkalosis…
pH:
[HCO3-]:
PCO2:
equation:

A

pH: increase
[HCO3-]: decrease
PCO2: decrease
equation: left

113
Q

Metabolic acidosis…
pH:
[HCO3-]:
PCO2:
equation:

A

pH: decrease
[HCO3-]: decrease
PCO2: NA
equation: left

114
Q

Metabolic alkalosis…
pH:
[HCO3-]:
PCO2:
equation:

A

pH: increase
[HCO3-]: increase
PCO2: NA
equation: right

115
Q

In metabolic acidosis compensation, which is larger…[HCO3]/[CO2]?

A

small/large
* needs to decrease CO2

116
Q

In metabolic alkalosis compensation, which is larger…[HCO3]/[CO2]?

A

large/small
* needs to increase CO2

117
Q

In respiratory acidosis compensation, which is larger…[HCO3]/[CO2]?

A

large/small
* needs to increase CO2

118
Q

In respiratory alkalosis compensation, which is larger…[HCO3]/[CO2]?

A

small/large
* needs to decrease CO2

OLD "MBS 603" (22 decks)

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