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Physio Exam 3 > Topic 9 > Flashcards

Topic 9 Flashcards

1
Q

Solute concentration & osmolarity determined by what?

A

Total amount of solute / Volume of extracellular fluid

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2
Q

Changing extracellular water has significant effect on what?

A

solute concentration and osmolarity

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3
Q

Body water determined by what 2 things?

A
  1. Fluid intake (controlled by thirst)

2. Renal excretion of water (controlled by changing GFR and tubular reabsorption

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4
Q

If ECF solute concentration increases, what ultimately happens?

A

kidneys hold onto water so ECF volume increases diluting ECF solutes

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5
Q

If ECF solute concentration decreases, what ultimately happens?

A

kidneys excrete more water so ECF volume decreases concentrating ECF solutes

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6
Q

Assuming normal solute intake and metabolic production: What will remain relatively constant each day

A

Solute excretion

–Total amount of solute in ECF relatively constant as well

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7
Q

Assuming normal solute intake and metabolic production: What is adjusted to keep solute concentration of ECF constant?

A

Quantity of water excreted each day

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8
Q

With Increased ECF [solute]/osmolarity: The Normal amount of solute dissolved is in ____ water

A

less

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9
Q

With Increased ECF [solute]/osmolarity: Holding onto water will spread the total amount of solute over larger volume of water thus…

A

decreasing solute concentration of ECF

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10
Q

With Decreased ECF [solute]/osmolarity: The Normal amount of solute dissolved is in ______ water

A

too much

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11
Q

With Decreased ECF [solute]/osmolarity: Getting rid of water will spread the total amount of solute over smaller volume of water thus…

A

increasing solute concentration of ECF

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12
Q

Posterior pituitary responds to changes in ECF osmolarity by changing what?

A

ADH release

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13
Q

Increased ECF osmolarity results in an

A

increased release of ADH

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14
Q

Decreased ECF osmolarity results in a

A

decreased release of ADH

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15
Q

Quantity of water excreted controlled by what?

A

[ADH]

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16
Q

What part of the kidney does ADH act on and influence water reabsorption?

A

distal tubule & collecting duct

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17
Q

Decreased [ADH] results in a decrease in what?

A

decrease in water

–reverse is true

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18
Q

Changes in water reabsorption controls what 2 things?

A

urine volume and urine solute concentration

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19
Q

Increased water reabsorption means ___ water enters collecting duct _____ overall volume of urine - Normal amount of excreted solutes now dissolved in ____ volume –> production of small amount of very _____ urine

A

less
decreasing
less
concentrated

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20
Q

max concentration of urine: mls/day and osmolarity

KNOW

A

500 mls/day with osmolarity of 1200 to 1400 mOsm/Liter

— so its a little urine that is very concentrated

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21
Q

Decreased water reabsorption means ____ water enters collecting duct _____ overall volume of urine – Normal amount of excreted solutes now dissolved in ____ volume –> production of large amount of very ____ urine

A

more
increasing
more
dilute

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22
Q

min concentration of urine: L/day and osmolarity

KNOW

A

20 Liters/day with osmolarity of 50 mOsm/Liter

— so its diluted urine with a small concentration

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23
Q

An Increase in ECF solute does what to osmolarity?

A

Increase

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24
Q

Posterior pituitary increases release of what?

A

ADH

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25
Q

Increase in [ADH] produces an increase in _____ in distal tubule and collecting duct

A

water permeability

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26
Q

Increase in water permeability increases amount of what?

A

water reabsorbed

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27
Q

Increase in water reabsorption increases water volume in ECF so total ECF solute spread out over larger water volume returning ECF osmolarity to what level?

A

normal level

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28
Q

Increase in water reabsorption decreases water volume in urine so total excreted solute spread out over less water volume which increases what?

A

increases urine osmolarity (less urine with higher osmolarity)

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29
Q

For dilute urine, what is the max L/day and the osmolarity? KNOW

A

Can excrete 20 liters/day with minimal concentration of 50 mOsm/Liter

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30
Q

Excretion of dilute urine means you have high or low ADH?

A

Low

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31
Q

For dilute urine, what amounts of solutes have been reabsorbed?

A

normals amounts

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32
Q

For dilute urine, what section do you Limit water reabsorption?

A

late distal tubule and collecting ducts

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33
Q

If you Drink 1 liter of water, Changes begin to occur in how many minutes?

A

45 min

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34
Q

After you drink 1 liter of water and wait 45 minutes for the changes, you get a Slight increase in

A

solute excretion

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35
Q

After you drink 1 liter of water and wait 45 minutes for the changes, you get a Slight decrease in

A

plasma osmolarity

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36
Q

After you drink 1 liter of water and wait 45 minutes for the changes, you get a Large decrease in

A

urine osmolarity [600 mOsm/L to 100 mOsm/L]

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37
Q

After you drink 1 liter of water and wait 45 minutes for the changes, you get a Large increase in

A

urine output [1 ml/min to 6 mls/min]

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38
Q

For dilute urine production,

Filtrate osmolarity = Plasma osmolarity… which is about?

A

≈ 300 mOsm/L

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39
Q

To produce dilute urine, solute has to be reabsorbed at a ____ rate than water

A

faster

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40
Q

To produce dilute urine (PROXIMAL TUBULE): Solute & water reabsorbed at what rate? Whats the change is osmolarity?

A

same rate

No change osmolarity

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41
Q

To produce dilute urine (DESCENDING LOOP): Water reabsorbed following gradient into what? Whats the change is osmolarity?

A

hypertonic interstitial fluid

Osmolarity increases 2 to 4 times osmolarity of plasma

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42
Q

To produce dilute urine (ASCENDING LOOP): What is reabsorbed? Whats the change is osmolarity?

A

Sodium, potassium, chloride reabsorbed
–No water reabsorbed regardless of [ADH]
Tubular osmolarity decreases to 100 mOsm/L
–1/3 osmolarity of plasma

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43
Q

To produce dilute urine (Distal Tubule & Collecting Tubules): What is reabsorbed? Whats the change is osmolarity?

A

Variable amount of water reabsorption based on [ADH]
–No ADH – No water reabsorption
Solute reabsorption continues–>further decreasing tubular osmolarity–Max dilution of 50 mOsm/Liter

44
Q

Must be able to concentrate urine when?

A

water intake is limited

45
Q

For concentrated urine, what is the max ml/day and the osmolarity? KNOW

A

Can excrete 500 mls/day with maximum concentration of 1200 to 1400 mOsm/Liter

46
Q

Excretion of concentrated urine means you have high or low ADH?

47
Q

For concentrated urine, what amounts of solutes have been reabsorbed?

A

normal amounts

48
Q

For concentrated urine, what section do you increase water reabsorption?

A

late distal tubule and collecting ducts

49
Q

Normal 70 kg person needs to excrete how much urine a day to get rid of toxic wastes? L/day? mOsm/day?

A

0.5 L/day

600 mOsm/day

50
Q

Sea water has salt content of?

A

3.5%

which is 35 g/Liter –> 1200 mOsm/Liter

51
Q

If the only water you have is sea water and you drink 1 Liter of sea water each day you need to remove 1200 mOsm of salt PLUS 600 mOsm of waste each day…what your urine out put and how much are you loosing overall?

A

(1200 + 600 mOsm) = (1800 mOsm/day / 1200 mOsm/Liter) = 1.5 Liters of urine / day
–Means you are losing 500 mls/day (become dehydrated)

52
Q

What 2 things are Needed To Produce Concentrated Urine?

A

High concentration of ADH

High osmolarity of renal medullary interstitial fluid

53
Q

High concentrations of ADH increases or decreases permeability of distal tubules & collecting ducts

54
Q

Water reabsorption is driven by what forces?

55
Q

Interstitial osmolarity setup by what mechanism?

A

the countercurrent mechanism

56
Q

Interstitial fluid surrounding collecting ducts normally _______ which provides the ______ for water reabsorption

A

hyperosmotic

gradient

57
Q

Once water leaves the distal tubule & collecting ducts it is quickly picked up by what?

A

the vasa recta capillary network

58
Q

Countercurrent Mechanism is made possible by anatomical arrangement of what 3 things?

A
  1. Loops of Henle (loops of the juxtamedullary nephrons that go deep into the renal medulla: 25% of total nephrons)
  2. Corresponding vasa recta capillaries (Parallel the loops)
  3. Collecting ducts (Carry urine down through the renal medulla)
59
Q

Urine osmolarity cannot exceed osmolarity of interstitial fluid in what?

A

renal medulla

60
Q

To produce concentrated urine of 1200 mOsm/Liter the osmolarity at the bottom of the renal medulla must be at least what?

A

1200 mOsm/Liter

61
Q

To create a Hyperosmotic Renal Medulla you Must accumulate solute in the?

A

medulla

–Once solute accumulated, hyperosmolarity maintained by a balanced inflow/outflow of water and solutes

62
Q

To create a Hyperosmotic Renal Medulla: Active ion transport & co-transport (Na+, K+, Cl-) out of thick portion of ascending loop into medullary interstitium is able to create a ______ concentration gradient

63
Q

To create a Hyperosmotic Renal Medulla: Thin descending limb highly permeable to water – As water is reabsorbed, osmolarity of tubular fluid does what?

A

decreases until it matched osmolarity of interstitial fluid

64
Q

To create a Hyperosmotic Renal Medulla: Active transport of ions from where into where

A

collecting duct into medullary interstititum

65
Q

To create a Hyperosmotic Renal Medulla: Facilitated diffusion of urea from where into where

A

inner medullary collecting ducts into medullary interstitium

66
Q

To create a Hyperosmotic Renal Medulla: More solute is reabsorbed into medullary interstitium than what?

67
Q

Osmolarity of tubular fluid entering distal tubule is LOW because of what 2 things?

A
  1. NO water permeability in thick ascending segment

2. Minimal water permeability in late distal tubule

68
Q

Collecting duct water permeability depends on what?

69
Q

With a HIGH ADH in Distal Tubule & Collecting Ducts: Large quantity of water reabsorbed by ______ –> Reabsorbed water carried away by _____

A

cortical collecting duct

peritubular capillaries

70
Q

With a HIGH ADH in Distal Tubule & Collecting Ducts: Medullary collecting duct HIGHLY permeable to water but…

A

only small percentage of water is left

71
Q

With a HIGH ADH in Distal Tubule & Collecting Ducts: Since amount of water relatively small, water permeability is high, and VASA RECTA able to carry water away, osmolarity inside collecting duct quickly equilibrates with what?

A

interstitial osmolarity

72
Q

Urea accounts for ___% of total osmolarity of inner renal medulla

73
Q

Normally excrete __% of filtered urea load

A

50%

–other 50% circles around again

74
Q

In the Descending & ascending – secretion of UREA into tubule so urea concentration continues to increase SLIGHTLY. This is facilitated by?

A

urea transported UT-A2

75
Q

Urea not permeable in what 4 spots?

A

Thick Ascending Loop, Distal Tubule, Cortical and OUTER Medullary Collecting Duct

76
Q

Where does urea concentration rises quickly as large volume of water is reabsorbed

A

collecting duct

77
Q

Where does Urea permeability increase so urea will diffuse out and into interstitial space?

A

INNER Medullary Collecting Duct

78
Q

What 2 things facilitates urea diffusion in the Inner Medullary Collecting Duct

A

urea transporters UT-A1 and UT-A3

–UT-A3 activated by ADH

79
Q

Water is still being reabsorbed so Inner Medullary Collecting Duct concentration of urea remains

80
Q

in the Medullary Collecting Duct Some of the urea is secreted back to where

A

back into the thin segments of the loop of Henle

81
Q

in the Medullary Collecting Duct Recirculation of urea (from collecting duct back into the loop of Henle) works to do what?

A

increase concentration of urea in the urine and inner medullary interstitium

82
Q

How do you meet metabolic needs of the vasa recta without washing out concentrated solute for urine concentration?

A
  1. Medullary blood flow very low (5% of total renal flow)

2. Vasa recta function as countercurrent exchangers

83
Q

Vasa Recta is Highly permeable to solute except what?

84
Q

as Vasa Recta descends, Water follows concentration gradient from? and Solute follows concentration gradient from?

A 
Water= concentration gradient from blood to interstitium
Solute= concentration gradient from interstitium to blood
85
Q

as Vasa Recta ascends, Water now follows gradient into? and Solute follows gradient out of?

A

Water now follows gradient into blood

Solute follows gradient out of blood

86
Q

Vasa Recta Carries away the amount of solute and water as is absorbed FROM the?

A

medullary tubules

87
Q

Increasing the blood flow through the vasa recta will “washout” solute thus…

A

reducing the overall solute concentration in the renal medulla

  • -Some vasodilators
  • -Large increases in arterial blood pressure( Flow through renal medulla affected more than flow through other areas of kidney)
88
Q

In the proximal tubule, 65% of filtered electrolytes are reabsorbed along with what?

A

proportional amount of water

89
Q

In the proximal tubule, Filtrate flow goes from?

A

125 mls/minute to 44 mls/minute

90
Q

In the descending loop:

  • high permeability for
  • low permeability for
  • osmolarity
  • levels of ADH
  • filtrate level (tubular flow)
A
  • high permeability for water
  • low permeability for sodium, chloride, urea
  • osmolarity matches interstitial osmolarity
  • levels of ADH are low (Urea absorption from collecting duct reduced so interstitial osmolarity also reduced)
  • filtrate level= 25 mls/minute tubular flow
91
Q

In the thin ascending loop:

  • water permeability
  • some reabsorption of
  • some diffusion of
  • osmolarity
  • filtrate level (tubular flow)
A
  • water permeability- NONE
  • some reabsorption of sodium, chloride
  • some diffusion of urea into tubule
  • osmolarity= Net result – decrease in osmolarity
  • filtrate level= No change (still 25 mls/minute)
92
Q

In the thick ascending loop:

  • water permeability
  • Active reabsorption of
  • osmolarity=
  • filtrate level (tubular flow)-
A
  • water permeability- NONE
  • Active reabsorption of sodium, chloride, potassium (Large amounts)
  • osmolarity= continues to decrease (200 to 100 mOsm/L)
  • filtrate level (tubular flow)- no change (still25 mls/minute)
93
Q

In early distal tubule:

  • known as
  • water permeability
  • Active reabsorption of
  • Osmolarity
  • filtrate level (tubular flow)-
A
  • known as diluting segment
  • water permeability- NONE
  • Active reabsorption of sodium, chloride, potassium (Large amounts)
  • Osmolarity- continues to decrease 50 mOsm/L
  • filtrate level- No change (still 25 mls/minute)
94
Q

in the Late Distal Tubule / Cortical Collecting Tubules, Osmolarity based on level of?

95
Q

in the Late Distal Tubule / Cortical Collecting Tubules, Urea permeability low so total urea load at this point does not change until where?

A

medullary collecting ducts

96
Q

Late Distal Tubule / Cortical Collecting Tubules with DILUTED urine: ____ water reabsorption and further ____ in osmolarity (ions still being reabsorbed). Tubular flow still around _____

A

Minimal
decrease
25 mls/minute

97
Q

Late Distal Tubule / Cortical Collecting Tubules with CONCENTRATED urine: ____ water reabsorption so osmolarity _____. Tubular flow drops to _____

A

High
increases
8 mls/minute

98
Q

in Medullary Collecting Tubules, Osmolarity depends on what 2 things?

A

[ADH] and interstitial osmolarity

99
Q

in Medullary Collecting Tubules with high [ADH]= High water permeability / reabsorption – Solute concentration increases (especially of ____). Tubular flow drops to____

A

urea

0.2 mls/minute

100
Q

in Medullary Collecting Tubules with low [ADH]= Low water permeability – Solute concentration drops as urea is reabsorbed. Slight decrease in tubular flow to ____

A

20 mls/minute

101
Q

in Medullary Collecting Tubules, Increased flow through vasa recta does what?

A

decreases overall solute concentration of interstitial fluid which decreases water reabsorption
–Not able to concentrate urine to as high a level or reabsorb as much water

102
Q

Kidneys can produce concentrated urine that contains little ____ or ____ even though under normal conditions they make up _____% of interstitial solute at max concentration

A

sodium or chloride

50 to 60

103
Q

Dehydration / low sodium intake – stimulate release of what 2 things?

A

angiotensin II and aldosterone

104
Q

Kidneys can produce large quantities of dilute urine without changing what? how does it do this?

A

sodium excretion

–Changing [ADH] which changes water reabsorption in later segments of nephron without changing sodium reabsorption

105
Q

the Obligatory urine volume dictated by what?

A

max ability to concentrate the urine

Physio Exam 3 (6 decks)

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