Sodium and Potassium Handling

Question 1

ANP, Sympathetics, Ang II

Increase or Decrease Body Sodium?

Answer 1

Increase body sodium

Question 2

Does ANP increase or decrease body sodium?

Answer 2

Decrease

Question 3

Increasing plasma sodium causes ____ to move into the vasculature

Answer 3

Water

Question 4

Normal Value for K

Answer 4

4

Question 5

Normal Value for Hgb

Answer 5

15

Question 6

Normal value for Sodium

Answer 6

140meq/L

Question 7

What matters more, sodium concentration or absolute sodium?

Answer 7

Concentration!

Question 8

What happens when somebody eats something salty?

Answer 8

Body will sense increase in plasma osmolarity, will release ADH to increase water retention (AQP in principal cells). This causes an expansion in effective blood volume, so the body will attempt to restore normovolemia + normotension. To do so, CO and TPR will be decreased, and the kidney will excrete water and salt.

Question 9

How does the kidney excrete water and salt in response to hyperosmolarity?

Answer 9

Higher BP (created by compensation) will lower FF (GFR doesnt change). Higher osmolarity will cause decreased renin release from macula densa cells. Therefore, ang II and aldo will be decreased, preventing reabsorption of Na in the prox and distal tubules. Cortical gradient will be decreased too, preventing water retention for CCD.

Question 10

Will people with access to water become hypernatremic?

Answer 10

No.

Question 11

What happens with excessive water consumption?

Answer 11

Decrease in plasma osmolality, ADH release suppressed, no AQP insertion, water excreted.

Question 12

Why can a person only excrete 16L/day H2O?

Answer 12

Because there is a minimum osmolarity needed!

Question 13

Why does a hypervolemic person keep excreting salt?

Answer 13

Because the body thinks it can excrete salt fine!

Question 14

What immediately happens to K as it is ingested?

Answer 14

It is moved into cells using the Na-K pump. Insulin increases its activity.

Question 15

How does hyperkalemia affect the adrenal gland?

Answer 15

Causes increase in RAAS, aldosterone is a potent stimulus for aldosterone secretion.

Question 16

K in the nephron

Answer 16

87% is reabsorbed by proximal tubule and loop of henle, but potent secretion occurs at principal cells.

Question 17

Effect of aldosterone on principal cell

Answer 17

Increases Na reabsorption, increases K secretion, increases activity of basal Na K pump.

Question 18

How does volume expansion affect K handling?

Answer 18

Volume expansion increases luminal flow, keeps K moving through the lumen.

Question 19

Effect of aldosterone on alpha intercalated cell?

Answer 19

Increased luminal K increases activity of the H-K transporter, causing acidification of the lumen, and increased BiCarb in the plasma.