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Flashcards in Renal Regulation of Electrolytes Deck (39)
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1

What 2 mechanisms are in charge of K+ homeostasis?

-K+ regulation mechanisms in the ECF
-Mechanisms adjusting renal K+ excretion to match dietary K+ intake

2

Where is most of the K+ in the body found?

In the ICF

3

How is the rapid rise in K+ in the ECF prevented after a meal?

This rise in plasma [K+] is prevented by the rapid (minutes) uptake of K+ into cells.

4

What is the effect of aldosterone, insulin and epinephrine on plasma [K+]?

It results in movement of K+ into the cells and decreases the plasma [K+]

5

What does epinephrine on alpha receptors stimulate?

K+ release from cells

6

What does cell lysis stimulate?

K+ release from cells

7

What does hyperosmolarity stimulate?

K+ release from cells due to cells shrinking and increasing the driving force on K+

8

What does epinephrine on beta-2 receptors stimulate?

K+ uptake into cells

9

What does aldosterone stimulate?

Stimulates the Na/K pump which increases the K+ excretion

10

What does hyposmolarity stimulate?

K+ uptake into cells as they swell and dilute the K+ inside the cell the driving force no the K+ going into the cell is increased.

11

What is the normal reabsorption of K+ in the kidneys?

85%

12

What are the 3 factors that regulate the rate of K+secretion by the DT and CD?

-Na/K ATPase Pump Actvity
-Tubular Cell to Tubular Lumen Gradient
-K+ Permeability of Apical Membrane

13

What is the effect of increased extracellular K+?

It stimulates the Na/K ATPase which leads to increased [K+] within the cell and this leads to increased K+ permeability of the apical membrane and results in increased K+ secretion.

Increased ECF [K+] will also increase aldosterone which will increase the K+ secretion via stimulation of Na/K ATPase pump

14

What is the effect of glucocorticoids on K+ secretion?

It will increase it indirectly by increasing the GFR

15

What is the effect of ADH on K+ secretion?

It has no net effect on the K+ secretion

16

Why does ADH have no net effect on K+ secretion?

This is due to the secretion of ADH occurring during antidiuresis which means the effect of ADH in increasing the K+ secretion would be opposed by the effect of the decreased urinary flow rate decreasing the K+ secretion.

These two effects cancel out and so the ADH had no effect on the K+ secretion.

17

What is the effect of increased DT flow rate on K+?

It will lead to increased K+ secretion but also decreased ADH. Decreased ADH will result in less active Na/K ATPase which will lead to decreased K+ secretion. These opposing effects will decrease or maintain the K+ balance.

18

What is the effect of decreased DT flow rate on K+?

It will lead to decreased K+ secretion but also increased ADH. Increased ADH will result in more active Na/K ATPase which will lead to increased K+ secretion. These opposing effects will increase or maintain the K+ balance.

19

What is the effect of acute metabolic acidosis on K+ secretion?

It will decreased the K+ permeability of the apical membrane in the DT and CD and this will lead to decreased K+ secretion and excretion.

20

What is the effect chronic metabolic acidosis on K+ secretion?

It will lead to increased K+ out exchange for H+ in exchange which will lead to increased plasma [K+]. This increase will activate the aldosterone system and increased the permeability of the apical membrane in the DT and CD and lead to increased K+ secretion and excretion.

21

What is the effect of furosemide, acetazolamide and mannitol on K+?

K+ wasting

22

What is the effect of spironolactone and amiloride on K+?

K+ sparing

23

Where is most of the Ca2+ in the body stored?

99% of the Ca in the body is stored in the bone

24

What is the general form that Ca is found as in the body?

Half of the Ca is found in the ionized form and half is found bound to protein

25

What happens to Ca in the case of acidosis?

Increases the ionized Ca -> hypercalcemia

26

What happens to Ca in the case of alkalosis?

Decreased the ionized Ca -> hypocalcemia

27

What is the effect of increased calcitriol on Ca?

It will increase the renal absorption of Ca2+

28

What is the function of parathyroid hormone?

It protects against low [Ca2+]

29

What is the function of calcitriol?

It protects against low [Ca2+]

30

What is the function of calcitonin?

It protects against high [Ca2+]

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