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Physiology > Renal Regulation of Electrolytes > Flashcards

Renal Regulation of Electrolytes Flashcards

1
Q

What 2 mechanisms are in charge of K+ homeostasis?

A
  • K+ regulation mechanisms in the ECF

- Mechanisms adjusting renal K+ excretion to match dietary K+ intake

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2
Q

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

A

In the ICF

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3
Q

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

A

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

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4
Q

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

A

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

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5
Q

What does epinephrine on alpha receptors stimulate?

A

K+ release from cells

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6
Q

What does cell lysis stimulate?

A

K+ release from cells

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7
Q

What does hyperosmolarity stimulate?

A

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

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8
Q

What does epinephrine on beta-2 receptors stimulate?

A

K+ uptake into cells

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9
Q

What does aldosterone stimulate?

A

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

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10
Q

What does hyposmolarity stimulate?

A

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.

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11
Q

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

A

85%

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12
Q

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

A
  • Na/K ATPase Pump Actvity
  • Tubular Cell to Tubular Lumen Gradient
  • K+ Permeability of Apical Membrane
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13
Q

What is the effect of increased extracellular K+?

A

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

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14
Q

What is the effect of glucocorticoids on K+ secretion?

A

It will increase it indirectly by increasing the GFR

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15
Q

What is the effect of ADH on K+ secretion?

A

It has no net effect on the K+ secretion

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16
Q

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

A

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
Q

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

A

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
Q

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

A

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
Q

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

A

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
Q

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

A

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
Q

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

A

K+ wasting

22
Q

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

A

K+ sparing

23
Q

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

A

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

24
Q

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

A

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

25
Q

What happens to Ca in the case of acidosis?

A

Increases the ionized Ca -> hypercalcemia

26
Q

What happens to Ca in the case of alkalosis?

A

Decreased the ionized Ca -> hypocalcemia

27
Q

What is the effect of increased calcitriol on Ca?

A

It will increase the renal absorption of Ca2+

28
Q

What is the function of parathyroid hormone?

A

It protects against low [Ca2+]

29
Q

What is the function of calcitriol?

A

It protects against low [Ca2+]

30
Q

What is the function of calcitonin?

A

It protects against high [Ca2+]

31
Q

What is the effect of PTH as Ca decreases?

A

It will lead to increased reabsorption of Ca by the kidneys and increase bone resorption as well as increased levels of calcitriol.

All of this will lead to increased [Ca2+]

32
Q

What is the effect of calcitriol on decreased Ca levels?

A

The parathyroid will increase calcitriol production with decreased [Ca2+]. Calcitriol increases the Ca2+ resorption from bone and decreases Ca2+ excretion in the kidneys.

33
Q

What is the effect of calcitonin on high levels of [Ca2+]?

A

Increases in Ca will increase the levels of calcitonin. It will lead to increased Ca deposition in the bone and increase Ca excretion, both of which will decrease the [Ca2+].

34
Q

How much of the filtered Ca2+ is reabsorbed by the kidney?

A

99%

35
Q

Where is most of the phosphate in the body found?

A

Bone. 86% of it is stored in the bone.

36
Q

How much of the Pi is normally reabsorbed in the PT?

A

80%. Pi is readily absorbed.

37
Q

What is the effect of PTH on the Pi?

A

It increases the level of the plasma Pi and increases Pi excretion.

38
Q

What is the effect of calcitriol on Pi?

A

It increases the level of the plasma Pi and decreases Pi excretion.

39
Q

What is the effect of calcitonin on Pi?

A

It decreases the level of plasma Pi and increases Pi excretion.

Physiology (81 decks)

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