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FHB Mikayla > Unit 2, L18 Renal Regulation of Electrolytes > Flashcards

Unit 2, L18 Renal Regulation of Electrolytes Flashcards

1
Q

What functions is K critical for?

A

Regulation of cell volume, regulation of intracellular pH, resting membrane potential, and cardiac and neuromuscular activity

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2
Q

What is the percentage of K found in the ICF

A

98%

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3
Q

What percentage of total body K is located in the ECF

A

2%

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4
Q

Value of K+ in ECF for hyperkalemia

A

Exceeding 5.0 mEq/L

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5
Q

Value of K+ in ECF for hypokalemia

A

Less than 3.5 mEq/L

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6
Q

The standard diet means consuming what amount of K per day

A

100 mEq of K per day

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7
Q

How much K gets absorbed in the intestines per day, assuming 100 mEq diet

A

90 mEq of K per day

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8
Q

How much K gets excreted through feces per day, assuming 100 mEq diet

A

5-10 mEq per day

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9
Q

Of the 90 mEq we absorb, how much of it is in the extracellular fluid initially?

A

65 mEq

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10
Q

What facilitates the movement of K from the extracellular fluid to the tissue stores?

A

Insulin, epinephrine, and aldosterone

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11
Q

After movement form extracellular fluid to the tissue stores, what is the concentration of K per day in the tissue stores

A

3435 mEq/day

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12
Q

What facilitates the excretion of extracellular fluid K?

A

Plasma K concentration, AVP, and aldosterone

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13
Q

How much K gets excreted through the urine, assuming a 100 mEq diet?

A

90-95 mEq

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14
Q

How much K is reabsorbed in the proximal tubule

A

67%

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15
Q

How much K is reabsorbed in the TAL of the loop of Henle

A

20%

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16
Q

K can be secreted where and through what cells

A

K is secreted in the distal tubule and collecting duct, and principal cells secrete K

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17
Q

What type of cells reabsorb K?

A

Alpha intercalated cells

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18
Q

In a normal diet, what is the percentages for K reabsorption and excreteion

A

85% is reabsorbed and 15% is excreted

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19
Q

If you have decreased dietary K, what happens to reabsorptionb

A

Increased reabsorption to 99%

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20
Q

If you have increased dietary K, what happens to excretion

A

Increased excretion, up to 80%

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21
Q

What are the factors that regulate the rate of K secretion from principal cells?

A

Na/K/ATPase pumps
Electrochemical gradient of K+ across the apical membrane
Permeability of the apical membrane to K

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22
Q

Increased K concentration outside of the cell will activate what signaling pathway for K secretion?

A

Increased extracellular K leads to stimulation of Na/K/ATPase, which leads to increased K inside of the cell, which increases K permeability of the apical membrane, which leads to increased K secretion

Additionally, increased extracellular K concentration can lead to increased aldosterone, which increases K secretion by inserting Na/K/ATPase pumps into the membrane

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23
Q

Physiological factors that keep plasma K constant

A

Epinephrine
Insulin
Aldosterone

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24
Q

Pathophysiological: displace plasma K from normal

A

Acid base disorders
Plasma osmolality
Cell lysis
Vigorous exercise

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25
Drugs that induce hyperkalemis
Dietary K supplements ACE inhibitors K sparing diuretics
26
What will alpha 1 receptor stimulation do in terms of K
Release K from the cells
27
What will beta 2 receptor stimulation do in terms of cells
Uptake K into cells
28
What is the most important hormone that shifts K into cells
Insulin
29
Function of aldosterone
Stimulation of Na/K/ATPase pump, increases urinary excretion of K
30
In hyposmolality, what happens to K?
Cells swell, so intracellular K concentration is diluted, increasing the driving force moving K into the cell
31
In hyperosmolality, what happens to K
The cells will shrink, so the intracellular K concentration is concentrated, which will increase the driving force to move K out of the cells
32
What conditions/events will cause K to shift out of cells (aka hyperkalemia)
``` Insulin deficiency Beta 2 adrenergic antagonists Alpha adrenergic agonists Acidossi Hyperosmolarity Cell lysis Exercise ```
33
What conditions causes K to shift into cells (hypokalemia)
``` Insulin Beta 2 adrenergic agonists Alpha adrenergic antagonists Alkalosis Hyposmolarity ```
34
What hormones will alter K secretion
Aldosterone, glucocorticoids (increased K excretion), and AVP
35
What happens to tubular flow when you have water diuresis
More water is in the tubular fluid, so you have an increase in urinary flow rate. You then get an increase in K secretion in the DT and CCD, as luminal K is being diluted because you have more water, so you have a larger concentration gradient by the time you reach the principal cells.
36
What happens to tubular flow rate if you are in a state of antidiuresis
There is decreased urinary flow rate, as you have less water, and this concentrates the luminal K concentration, decreasing the concentration gradient for K, which will decrease DT/CCD K secretion
37
What happens to AVP if you are in a state of water diuresis
Decreased AVP, so no additional AQP channels are being inserted into the apical membrane of the principal cells, and less Na movement into the cell, so there is decreased K secretion
38
What happens to AVP when you are in a state of antidiuresis
Increased AVP, means more AQP channels are being inserted into the apical membrane of the principal cells, allowing for more Na movement into the cell. Because you are moving more Na, this will also allow for more K movement out, so you get increased K secretion
39
Sensitivity of K secretion to tubular flow rate is ____________ to K amount in diet
Proportional
40
K wasting diuretics
Furosemide, acetazolamide, and mannitol
41
K sparing diuretics
Spironolactone, amiloride, and triamterene
42
What are the main two mechanisms behind K wasting diuretics?
1) In principal cells, increased Na uptake, as well as more activity of Na/K/ATPase. K is being pumped into cells, increasing driving force for K secretion from principal cells 2) Increased flow rate; luminal K is diluted, thus increasing driving force for K secretion from the principal cells
43
What are the three mechanisms for loop-specific diuretics
1) In principal cells, increased Na uptake, as well as more activity of Na/K/ATPase. K is being pumped into cells, increasing driving force for K secretion from principal cells 2) Increased flow rate; luminal K is diluted, thus increasing driving force for K secretion from the principal cells 3) Direct inhibition of the Na/K/Cl co-transporter
44
What do loop diuretics and thiazide diuretics inhibit
Na upstream of K secretion sites
45
What is the mechanism behind K sparing diuretics?
These diuretics act on the actions of the cells that are affected by aldosterone sensitive cells, ie on principal cells The K sparing diuretics inhibit Na transport in the principal cells, and Na/K/ATPase activity is downregulated, so K secretion is decreased
46
Acute metabolic acidosis will cause what for K secretion and excretion
Acute metabolic acidosis will decrease Na/K/ATPase activity as well as K permeability in the apical membrane of the pincipal cells in the distal tubule and collecting duct, both of which will lead to decreased K secretion and decreased K excretion
47
If you have chronic metabolic acidosis, what will happen to K secretion and excretion
For chronic, it comes from acute, which has decreased K excretion. If there is decreased K excretion, then there will be increased plasma K concentration. (There will also be increased plasma K concentration because of an increase in the H+/K exchanger). This leads to activation of aldosterone, which will act in the distal tubule and the collecting duct on the principal cells to increase Na/K/ATPase activity and K permeability in the apical membrane, thus increasing K secretion and excretion. Additionally, in the proximal tubule, you will have decreased NaCl and H2O reabsorption and increased tubular fluid flow rate, both of which will contribute to the effects seen in the distal tubule and collecting duct
48
What are the cellular processes in which Ca2+ plays an important role
Bone formation, cell division and growth, blood coagulation, hormone-response coupling, and electrical stimulus-response coupling
49
What percentage of Ca is found in ICF and ECF
1% in ICF and 0.1% in ECF
50
What percentage of Calcium is ionized, complexed, or protein bound?
Ionized: 50% Complexed: 10% Protein bound: 40%
51
In acidosis, what happens to ionized Ca
Increased ionized Ca, so hypercalcemia
52
In alkalosis, what happens to ionized Ca
Decreased ionized Ca, so hypocalemia
53
How does acidosis increase plasma Ca
H can compete with Ca for binding to anionic sites on proteins or small molecules so it can displace the Ca and pushes it into the ECF
54
Acute alkalosis can cause signs and symptoms mimicking what
Hypocalemia
55
Ca binding to plasma proteins depends on _____
Protein concentration, especially albumin
56
What percentage of Pi is stored in Bone ICF ECF Protein bound
Bone is 86% ICF is 14% ECF is 0.03% Protein bound is 10%
57
Dietary intake of phosphate is how much per day
1400 mg/day
58
GI excretion of phosphate per day
500 mg/day
59
In adults, the kidneys maintain total body Pi balance bt
Excreting an amount of Pi in the urine equal to the amount absorbed by the intestinal tract (900 mg/day)
60
If Pi is moving from intestine to phosphate pool, what is that called
Absorption
61
If Pi is moving from bone and soft tissue to the phosphate pool, what is that called
Resorption
62
What will Calcitriol do for Pi
Calcitriol will have 2 actions 1) when paired with PTH, will faciliate resorption of Pi from bone to phosphate pool 2) Will inhibit excretion from kidneys in the urine
63
What will PTH do to Pi
Two actions 1) When paired with Calcitriol, will facilitate resorption from bone and soft tissue to phosphate pool 2) When paired with FGF-23, will increase excretion from kidneys in urine
64
Dietary intake of Ca per day
1000 mg
65
Amount of Ca excreted out of the feces
800 mg
66
Amount of Ca excreted through urine
200 mg
67
What does Calcitriol do for Ca
3 actions 1) With PTH, will facilitate resorption from bone to calcium pool 2) Will inhibit excretion of Ca through urine 3) Will increase Ca absorbed from intestine
68
What will PTH do for Ca
2 things 1) With calcitriol, will inhibit excretion of Ca from kidneys as urine 2) With calcitriol, will facilitate resorption from bone to calcium pool
69
How much filtered Ca is reabsorbed by the nephron
About 99%
70
The proximal tubule reabsorbs what percentage of Ca
50-70%
71
The TAL reabsorbs what percentage of Ca
20%
72
The distal tubule reabsorbs what percentage of Ca
9-10%
73
Increased plasma Pi does what to plasma Ca, PTH, and Pi excretion
Reduces plasma Ca concentrations, therefore increases plasma PTH, which increases Pi excretion by the kidneys
74
What is the most important hormone to control Pi excretion and how does it work
PTH is the most important hormone and it inhibits Pi reabsorption by the proximal tubule and thereby increases Pi excretion
75
Increased plasma Pi will also do what to FGF-23 and calcitriol
Increased plasma Pi increases FGF-23, which increases Pi excretion and increases calcitriol production by the proximal tubule However, will also suppress calcitriol production, which results in a decrease in intestinal Pi reabsorption
76
Function of FGF-23
Inhibits Pi reabsorption and inhibits calcitriol production Secretion is stimulated by sustained hyperphosphatemia, PTH, and calcitriol FGF-23 is the brake
77
Calcitriol's effect on Ca and phosphate
Stimulates Ca and phosphate uptake from GI tract, and stimulates renal reabsorption of Ca and phosphate. Maintains normal bone remodeling
78
PTH's effect on Ca and phosphate
Stimulates rapid transfer of Ca and phosphate from bone and stimulates slower bone resorption. Also increases renal excretion of phosphate and stimulates renal reabsorption of Ca
79
FGF-23's effect on Ca and Phosphate
Increases renal excretion of phosphate, and increases renal reabsorption of Ca
80
Effect of Calcitriol on other hormones
Suppresses PTH synthesis, stimulates FGF-23 secretion
81
PTH's effect on other hormones
Stimulates renal production of calcitriol
82
FGF-23's effect on other hormones
Decreases renal production of calcitriol

FHB Mikayla (26 decks)

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