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Physio II > Urine Concentration- Exam 4 > Flashcards

Urine Concentration- Exam 4 Flashcards

1
Q

What is the major controlling agent for water in the body?

A

ADH

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2
Q

Extracellular fluid must have a constant concentration of what?

A

Electrolytes and other solutes

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3
Q

What is solute concentration and osmolarity determined by?

A

Total amount of solute / volume of extracellular fluid

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4
Q

Changing extracellular water has significant effect on what?

A

Solute concentration and osmolarity

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5
Q

What is body water determined by?

A 
Fluid intake (controlled by thirst)
Renal excretion of water (controlled by changing GFR and tubular reabsorption)
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6
Q

If ECF solute concentration increases, kidneys hold onto water so ECF volume __________(increases/decreases), _________ECF solutes.

A

Increases, diluting

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7
Q

If ECF solute concentration decreases, kidneys excrete more water so ECF volume (increases/decreases), ________ ECF solutes.

A

decreases, concentrating

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8
Q

Assuming normal solute intake and metabolic production: what will happen to solute excretion each day? What will happen to total amount of solute in ECF?

A

Solute excretion will remain relatively constant each day.

Total amount of solute in ECF relatively constant.

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9
Q

What is adjusted each day to keep solute concentration of ECF constant?

A

Quantity of water excreted each day is adjusted

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10
Q

Increased ECF [solute]: ________ECF osmolarity

A

increased

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11
Q

What responds to changes in ECF osmolarity by changing ADH release?

A

Posterior pituitary

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12
Q

Increased ECF osmolarity results in what?

A

Increased release of ADH

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13
Q

Decreased ECF osmolarity results in what?

A

decreased release of ADH

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14
Q

Quantity of water excreted is controlled by what?

A

ADH

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15
Q

Increased ADH results in an increase in water reabsorption by what?

A

Distal tubule & collecting duct

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16
Q

Decreased ADH results in a decrease in water reabsorption by what?

A

Distal tubule & collecting duct

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17
Q

What controls urine volume and urine solute concentration?

A

Changes in water reabsorption

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18
Q

Increased water reabsorption means less water enters what part of the nephron? What does this do to the volume of urine?

A

Collecting duct; decreases overall volume of urine

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19
Q

What is the max concentration? (mls/day and osmolarity)

A

500 mls/day
osmolarity of 1200 to 1400 mOsm/L
TOtal solute excreted: 700 mOsm/day

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20
Q

What is the minimum concentration of urine? How many L/min?

A

20L/day with osmolarity of 50 mOsm/L

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21
Q

If you have dilute urine, how much ADH do you have?

A

Low amounts

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22
Q

Describe the reabsorption of solutes with the present of dilute urine.

A

Normal amounts of solutes are reabsorbed

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23
Q

When producing dilute urine, there is limited water reabsorption in what parts of the nephron?

A

Late distal tubule and collecting ducts

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24
Q

If you drink 1 Liter of water, changes being to occur within how long?

A

45 minutes

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25
Q

During water diuresis, there is a slight _______in solute excretion.

A

Increase

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26
Q

During water diuresis, there is a slight _________ is plasma osmolarity.

A

decrease

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27
Q

During water diuresis, there is a large _________ in urine osmolarity

A

decrease

28
Q

What is the decrease in urine osmolarity in water diuresis?

A

600 mOsm/L to 100 mOsm/L

29
Q

During water diuresis, there is a large ______ in urine output.

A

increase

30
Q

How much of an increase in urine output occurs in water diuresis?

A

1 ml/min to 6 mls/min

31
Q

In the production of dilute urine, filtrate osmolarity is equal to what?

A

Plasma osmolarity; 300 mOsm/L

32
Q

To produce dilute urine, what has to happen?

A

Solute has to be reabsorbed at a faster rate than water

33
Q

In the proximal tubule, how does the rate of solute reabsorption compare to the rate of water reabsorption?

A

Reabsorbed at the same rate; no change in osmolarity

34
Q

In the descending loop, what drives water to be reabsorbed?

A

Gradient into hypertonic interstitial fluid

35
Q

How much does the osmolarity increase in the descending loop?

A

2 to 4x osmolarity of plasma

36
Q

What is reabsorbed in the ascending loop? [Production of dilute urine]

A

Sodium, potassium, chloride reabsorbed

37
Q

How much water is reabsorbed in the ascending loop? [Production of dilute urine]?

A

No water reabsorbed, regardless of [ADH]

38
Q

How much does the tubular osmolarity change in the ascneding loop? [ Production of dilute urine ] How does this compare to the osmolarity of plasma?

A

Decreases to 200 mOsm/L

1/3 osmolarity of plasma

39
Q

Describe the water reabsorption in the distal tubule and the collecting tubules. [Production of dilute urine]

A

Variable amount of water reabsorption based on [ADH]

No ADH = no water reabsorption

40
Q

Describe the solute reabsorption in the distal tubule and the collecting tubules. [ Production of dilute urine]

A

Solute reabsorption continues further decreasing tubular osmolarity

41
Q

What is the max dilution in the distal tubule and collecting tubules? [ Production of dilute urine]

A

Max dilution of 50 mOsm/L

42
Q

In what ways are we already losing water?

A

Breathing, sweat, feces, urine

43
Q

What must we be able to do when water intake is limited?

A

Concentrate urine

44
Q

We can excrete ______mls/day with maximum concentration of ______ to______ mOsm/L

A

500 mls/day ; 1200 to 1400 mOsm/L

45
Q

Describe the level of ADH when excreting concentrated urine.

A

High concentration of ADH

46
Q

Describe the reabsoprtion of solutes during excrete of concentrated urine.

A

Reabsorb normal amounts of solute

47
Q

Describe the water absorption in the late distal tubule and collecting ducts during the excretion of concentrated urine.

A

Increased

48
Q

What is meant by obligatory urine volume?

A

Some urine has to be produced each day to excrete the waste products of metabolism and ingested ions

49
Q

What dictates the obligatory urine volume?

A

Ability to concentrate urine

50
Q

A normal 70 kg person needs to excrete how many mOsm/day

A

600 mOsm/day

51
Q

A normal 70 kg person needs to excrete how many L/day?

A

600mOsm/day / 1200mOsm/L = 0.5L/day

52
Q

What is the salt content in sea water?

A

3.5%

53
Q

If the only water you have is sea water and you drink 1 L of sea water each day you need to remove how many mOsm salt + how many mOsm of waste each day?

A

1200 mOsm salt

600 mOsm of waste each day

54
Q

When drink a liter of sea water each day, you are losing how many mls of volume each day?

A

500 mls; which means you would become quickly dehydrated

55
Q

What is needed to produce concentrated urine?

A

High concentration of ADH

High osmolarity of renal medullary interstitial fluid

56
Q

What sets up interstitial osmolarity in renal medullary interstitial fluid?

A

Countercurrent mechanism

57
Q

What is important about interstitial fluid surrounding collecting ducts being hyperosmotic?

A

Provides the gradient for water reabsorption

58
Q

What picks up water once water leaves the distal tubule and collecting ducts?

A

Vasa recta capillary network

59
Q

Countercurrent mechanism is made possibly by anatomical arrangement of what?

A

Loops of henle
Corresponding vasa recta capillaries
Collecting ducts

60
Q

Countercurrent Mechanism: Loops of Henle

A

Especially loops of the juxtamedullary nephrons that go deep into the renal medulla
(25% of the total nephrons)

61
Q

Where are the vasa recta capillaries?

A

Parallel the loops

62
Q

What do the collecting ducts to?

A

Carry urine through the renal medulla

63
Q

Urine osmolarity cannot exceed osmolarity of what?

A

Interstitial fluid in the renal medulla

64
Q

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

A

1200 mOsm/L

65
Q

What must happen to create a hyperosmotic renal medulla?

A

Must accumulate solute in the medulla

66
Q

Once solute is accumulated, hyperosmolarity is maintained by what?

A

By a balanced inflow/outflow of water and solutes

Physio II (14 decks)

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