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Physio Exam 3 > Topic 11 > Flashcards

Topic 11 Flashcards

1
Q

Potassium is Tightly controlled–Usually changes less

than ____ mEq/liter

A

0.3 mEq/liter

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2
Q

how much potassium is intracellular and how much is extracellular? %

A

Intracellular 98%

extracellular 2%

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3
Q

what does the normal intake of potassium range between?

A

50 mEq/liter to 200 mEq/liter

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4
Q

how much of the potassium intake is removed by feces

A

5-10%

–rest must be removed by kidneys

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5
Q

After ingesting 40 mEq of K+ into ECF–[K+] would increase by how many mEq/l

A
  1. 8 mEq/liter

- -Most ingested K+ quickly moves into the cellular volume

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6
Q

what does Insulin move into the cells following a meal

A

potassium AND glucose

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7
Q

what is aldosterone secretion stimulated by

A

increased potassium concentration

–In disease state, ability to move K+ into the cells AND K+ reabsorption are affected

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8
Q

Epinephrine stimulates ______ receptors increasing movement of K+ into the cell.

A

β2- adrenergic

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9
Q

what do β2-adrenergic blocking agents (treat hypertension) lead to

A

hyperkalemia

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10
Q

what are 4 Factors that shifts K+ into cells (Potential hypo)

A
  1. Insulin
  2. Aldosterone (also K+ secretion)
  3. Β-adrenergic stimulation
  4. Alkalosis
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11
Q

what are 7 Factors that shifts K+ out of cells (Potential hyper)

A
  1. Insulin deficiency (diabetes mellitus)
  2. Aldosterone deficiency (Addison’s disease)
  3. Β-adrenergic blockade
  4. Acidosis
  5. Cell lysis
  6. Strenuous exercise
  7. Increased extracellular fluid osmolarity
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12
Q

what will will reduce action of Na-K ATPase with less transfer of K+ into the cells

A

Increased [H+]

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13
Q

what does cell lysis do

A

dumps intracellular K+ in extracellular compartment

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14
Q

With an increase in extracellular osmolarity, water moves out of the cell increasing intracellular [K+] which does what?

A

increases the rate of K+ diffusion out of the cell

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15
Q

the Excretion rate of potassium is determined by what 3 things?

A

Rate of potassium filtration
Rate of potassium reabsorption
Rate of potassium secretion

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16
Q

how often does the Constant fraction of filtered load reabsorbed in proximal tubule and the loop of Henle change

A

Does not change day-to-day

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17
Q

how much potassium is filtered in mEq/day

A

756 mEq/day

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18
Q

whats the Consistent Reabsorption % in the proximal tubule

A

65%

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19
Q

whats the Consistent Reabsorption % in the loop

A

25-30% (mainly thick ascending)

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20
Q

Flexible Reabsorption & Secretion occurs where

A

Principle cells of distal tubule and cortical collecting tubule

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21
Q

With normal K+ intake of 100 mEq/day, how much is removed by feces and how much by the kidneys

A

Feces removes 8 mEq

Kidneys must remove 92 mEq

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22
Q

Proximal tubule removes ___ mEq leaving ___ mEq
Loop removes ___ mEq leaving ___ mEq
Distal tubule & cortical collecting tubule MUST secrete ___ mEq (Approximately ___ of excreted potassium)

A

Proximal tubule removes 491 mEq leaving 265 mEq
Loop removes 204 mEq leaving 61mEq
Distal tubule & cortical collecting tubule MUST secrete 31 mEq (Approximately 1/3 of excreted potassium)

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23
Q

Principal Cells Make up __% of cells in late distal and cortical collecting tubule

A

90%

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24
Q

what do Intercalated Cells do

A

Reabsorb potassium especially during potassium

depletion

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25
Q

describe the H-K ATPase pump

A

Located tubular membrane
Pumps H+ from tubular cell into lumen (secretion)
Pumps K+ from tubular lumen into cell (reabsorption)
Major effect only during potassium depletion

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26
Q

what Three factors control rate of K+ secretion

A
  1. Activity of Na-K ATPase
  2. Electrochemical gradient for K+ movement from the blood to the tubular lumen
  3. Permeability of tubular membrane to K+
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27
Q

what will increase Stimulation of Potassium Secretion

A

Increased extracellular [K+]
Increased [aldosterone]
Increased tubular flow rate

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28
Q

what will decrease Stimulation of Potassium Secretion

A

Increased [H+] will DECREASE potassium secretion

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29
Q

Increase [K+] in plasma stimulated release of what?

A

aldosterone

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30
Q

Increased aldosterone increases what

A

increases rate of sodium reabsorption by late distal tubule and collecting duct

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31
Q

increases int the rate of sodium reabsorption by late distal tubule and collecting duct then increases what 2 things

A
  1. Increases activity of Na-K ATPase–so an increase in
    sodium reabsorption will also increase potassium secretion
  2. Increases tubular membrane permeability for potassium
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32
Q

Normal aldosterone level is approximately __ nag/dL

A

6 nag/dL

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33
Q

High aldosterone (primary aldosteronism) will result in what?

A

Hypokalemia

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34
Q

Low aldosterone (Addison’s disease) will result in what?

A

Hyperkalemia

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35
Q

Increased distal tubular flow rate will do what?

A

increase potassium secretion

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36
Q

Increased tubular flow rate can be caused by what?

A

volume expansion; high sodium intake; specific diuretics

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37
Q

Relationship between tubular flow rate and potassium secretion greatly affected by potassium intake… So a Higher the intake does what?

A

Higher the intake, the greater the effect created by tubular flow

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38
Q

As potassium diffuses into tubular lumen, what will happen?

A

the increase in luminal concentration will decrease the gradient thus decreasing the movement of potassium

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39
Q

Increased tubular flow carries potassium away thus

helping to preserve the gradient. So the higher flows will do what?

A

The higher the flow the better the gradient is preserved, the more potassium is secreted

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40
Q

Assuming high Na+ intake, Aldosterone secretion
decreases which will produce a decrease K+ secretion…BUT since sodium reabsorption is decreased,
what will happen to the overall distal tubular flow

A

overall distal tubular flow is increased which results in an
increase in K+ secretion
THE TWO OFF SET EACH OTHER

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41
Q

how does Acidosis (H+) reduces potassium secretion

A

Reduces the activity of Na-K ATPase–decreases driving force for moving potassium from cell interior to tubular
lumen

42
Q

what does Prolonged acidosis produce

A

increased potassium excretion–Result of decreased reabsorption of sodium chloride and water in proximal tubule and increased distal tubular flow

43
Q

acidosis does what to potassium secretion

A

reduces potassium secretion

44
Q

Alkalosis does what to potassium secretion

A

increases potassium secretion

45
Q

Total calcium in plasma: ___ mEq/liter

A

5 mEq/liter

46
Q

Total % calcium in ionized form

47
Q

Total % calcium bound to plasma protein

48
Q

Total % calcium bound in non-ionized form to other ions (phosphate, citrate)

49
Q

Amount of Ca++ bound to protein ____ with an increase in [H+].

50
Q

Patients with alkalosis more susceptible to what

A

hypocalcemic tetany

51
Q

Normal ion concentration of Ca++: __ mEq/liter (__ mmol/liter)

A

2.4 mEq/liter (1.2 mmol/liter)

52
Q

Hypocalcemia does what to neuromuscular excitability

A

increases muscle and nerve excitability (hypocalcemic tetany)

53
Q

Hypercalcemia does what to neuromuscular excitability

A

depressed neuromuscular excitability which can lead to cardiac arrhythmias

54
Q

what % of calcium stored in bone

55
Q

what will the body do if calcium levels increase or decrease too much

A
  • -if plasma concentration drops, body will move calcium from the bone
  • -if plasma concentration rises, body will move calcium back into the bone
56
Q

what % of calcium is present in intracellular space and cell organelles

57
Q

what % of calcium is present in extracellular fluid

58
Q

what is the most important control agent for calcium

A

Parathyroid Hormone (PTH)

59
Q 
Parathyroid Hormone (PTH):
\_\_% excreted via gastrointestinal tract (feces) (≈900 mg/day)
\_\_% excreted via kidneys (urine) (≈100 mg/day)
A

90% excreted via gastrointestinal tract (feces) (≈900 mg/day)
10% excreted via kidneys (urine) (≈100 mg/day)

60
Q

PTH regulation accomplished through what 3 actions

A
  1. Stimulation of bone resporption of calcium
  2. Stimulation of vitamin D which stimulates calcium
    reabsorption by intestines
  3. Direct stimulation of renal tubule reabsorption of calcium
61
Q 
fill in the path:
decrease of Ca++=
\_\_\_\_\_\_ PTH= 
\_\_\_\_\_\_ Ca++ released from bones
\_\_\_\_\_\_ Renal Ca++ reabsorption
\_\_\_\_\_\_ Vit D3 activation=
\_\_\_\_\_\_ Intestinal Ca++ reabsorption
A 
decrease of Ca++=
INCREASE PTH= 
INCREASE Ca++ released from bones
INCREASE Renal Ca++ reabsorption
INCREASE Vit D3 activation=
INCREASE Intestinal Ca++ reabsorption
62
Q 
Fill in the path:
Increased Na+ intake=
\_\_\_\_\_ aldosterone
\_\_\_\_\_ GFR
\_\_\_\_\_ Prox. Tubule Reabsorption
\_\_\_\_\_ Dist. Tubule flow rate
\_\_\_\_\_ K+ secretion cortical collecting ducts/Unchanged K+ Excretion
A

Increased Na+ intake=

  • -Decreased aldosterone
  • -Increased GFR
  • -Decreased Prox. Tubule Reabsorption
  • -Increased Dist. Tubule flow rate
  • -decreased with decreased alosterone OR increased with increased dist. tubule flow K+ secretion cortical collecting ducts/Unchanged K+ Excretion
63
Q

As extracellular calcium concentration falls: Parathyroid gland directly stimulated to do what

A

increase secretion of PTH

64
Q

Increased PTH concentration stimulates bone to do what

A

increase release of bone salts (resporption) which includes the release of large amounts of calcium

65
Q

As extracellular calcium concentration increases: Parathyroid gland does what

A

decreases PTH secretion

66
Q

Decreased PTH concentration does what

A

ecreases salt resporption to point where calcium will be added to the bone

67
Q

calcium is Freely filtered, reabsorbed BUT NOT secreted… so what is the excretion formula for CALCIUM

A

Excretion rate = Filtration–Reabsorption

68
Q

CALCIUM
Proximal tubule: __% filtered load reabsorbed
Loop of Henle: __ to __% filtered load reabsorbed
Distal tubule / Collecting tubule: __% filtered load
reabsorbed

A

Proximal tubule: 65%
Loop of Henle: 25 to 30%
Distal tubule / Collecting tubule: 4 to 9%

69
Q

what % of calcium in the filtered load is excreted

70
Q

Proximal Tubule Reabsorption of Ca++
__% of amount reabsorbed carried by water via paracellular pathway
__% of amount reabsorbed via a transcellular pathway

A

80% paracellular pathway

20% transcellular pathway

71
Q

what 2 ways are calcium Pumped out of cell across basolateral membrane

A

Ca ATPase pump

Na-Ca counter-transport mechanism

72
Q

Thick Ascending Loop–Ca++ Reabsorption
Paracellular pathway accounts for __% of reabsorption
Transcellular pathway accounts for __% of reabsorption

A

Paracellular pathway accounts for 50%

Transcellular pathway accounts for 50%

73
Q

in the thick ascending loop, describe how Ca++ is reabsorbed in the paracellular pathway

A

Passive diffusion down electrical gradient–lumen has slight positive charge compared to interstitial fluid

74
Q

in the thick ascending loop, describe how Ca++ is reabsorbed in the transcellular pathway

A 
Active process stimulated by PTH, Vitamin D (Calcitrol),
and calcitonin (PTH concentration most important)
75
Q

Distal Tubule–Ca++ Reabsorption

Almost all transport via what pathway

A

Transcellular pathway

–Active transport across basolateral membrane–diffusion into cell

76
Q

in the distal tubule what will increase reabsorption of Ca++

A

Increased [PTH], Vitamin D and calcitonin

77
Q

increased [PTH] stimulates increased reabsorption in what area

A

Loop and Distal Tubule

78
Q

PTH has no effect in what area

A

Proximal Tubule (Following sodium and water reabsorption)

79
Q

Δ in EC fluid volume and blood pressure cause inverse changes in sodium & water reabsorption which causes what

A

parallel changes in calcium reabsorption

80
Q

[Phosphate] affects [PTH]–As [Phosphate] increases, [PTH] does what

81
Q

[H+] major affect is on the transport mechanisms in what area

A

Distal Tubule

82
Q

name 6 things that will increase Ca++ Reabsorption

A 
increase [PTH] 
increase Plasma Phosphate
decrease EC Fluid Volume
decrease Blood Pressure
Metabolic Acidosis
Vitamin D3
83
Q

name 5 things that will decrease Ca++ Reabsorption

A 
decrease [PTH] 
decrease Plasma Phosphate
increase EC Fluid Volume
increase Blood Pressure
Metabolic Alkalosis
84
Q

Phosphate: Normal tubular maximum of ___ mMol/minute

A

0.1 mMol/minute

85
Q

Phosphate: If filtered load under Tmax, all phosphate is

A

reabsorber

86
Q

Phosphate: If filtered load over Tmax, phosphate is

87
Q

Phosphate: Plasma threshold level approximately ___ mMol/liter

A

0.8 mMol/liter

88
Q

Phosphate: Normal plasma concentration around __ mMol/liter

A

1 mMol/liter

–Large intake of phosphate each day (milk & meat)

89
Q

PHOSPHATE
Proximal Tubule: ___% of filtered phosphate reabsorbed
Loop of Henle: _______
Distal Tubule: __% of filtered phosphate reabsorbed
Collecting Tubule: ____________

A

Proximal Tubule: 75-80% of filtered phosphate reabsorbed
Loop of Henle: Very small amounts
Distal Tubule: 10% of filtered phosphate reabsorbed
Collecting Tubule: Very small amounts

90
Q

how does phosphate enter and leave the cell

A
  • -Enters cells from lumen via Na-Phosphate co-transport mechanism
  • -Leaves cell via counter-transport mechanism across basolateral membrane
91
Q

what % of filtered phosphate is excreted

92
Q

phosphate Tmax can change based on intake. with a Low intake, what will happen to the Tmax

A

Tmax will increase over time

93
Q

As PTH increases bone resorption of calcium, what happens to phosphate

A

phosphate is also resorbed

94
Q

increasing [PTH] does what to the Tmax for phosphate

A

decreases the Tmax for phosphate so less phosphate is reabsorbed and more is excreted

95
Q

how much magnesium is stored in bone, extracellular and intracellular volume

A

> 50% stored in bone
Most of what is left is located in the intracellular volume
<1% located in extracellular volume

96
Q

TOTAL plasma magnesium = __ mEq/liter BUT__% is bound to plasma proteins so free ionized is __ mEq/liter

A

TOTAL plasma magnesium = 1.8 mEq/liter
>50% is bound to plasma proteins
free ionized is 0.8 mEq/liter

97
Q

what is the daily intake of magnesium, and how much is absorbed by the GI tract

A

Daily intake ≈ 250 to 300 mg/day BUT only 50% is actually absorbed by the gastrointestinal tract (125 to 150 mg/day)
–The amount absorbed is the amount the kidneys must
excrete each day

98
Q

what % of magnesium is excreted from the filtered load

A

Renal excretion of magnesium is ≈ 10 to 15% of filtered load

99
Q

MAGNESIUM
Proximal Tubule: __% of filtered load
Loop of Henle: Primary site of reabsorption–__% of filtered load
Distal Tubule / Collecting Tubule: <_% of filtered load

A

Proximal Tubule: 25%
Loop of Henle: 65%
Distal Tubule / Collecting Tubule: <5%

100
Q

increased [magnesium] has what effects on reabsorption and excretion

A

decreased reabsorption

increased excretion

101
Q

increased EC fluid has what effects on reabsorption and excretion

A

decreased reabsorption

increased excretion

102
Q

increased [Ca++] has what effects on reabsorption and excretion

A

decreased reabsorption

increased excretion

Physio Exam 3 (6 decks)

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