Flashcards in Sodium and Potassium Handling Deck (19):
ANP, Sympathetics, Ang II
Increase or Decrease Body Sodium?
Increase body sodium
Does ANP increase or decrease body sodium?
Increasing plasma sodium causes ____ to move into the vasculature
Normal Value for K
Normal Value for Hgb
Normal value for Sodium
What matters more, sodium concentration or absolute sodium?
What happens when somebody eats something salty?
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.
How does the kidney excrete water and salt in response to hyperosmolarity?
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.
Will people with access to water become hypernatremic?
What happens with excessive water consumption?
Decrease in plasma osmolality, ADH release suppressed, no AQP insertion, water excreted.
Why can a person only excrete 16L/day H2O?
Because there is a minimum osmolarity needed!
Why does a hypervolemic person keep excreting salt?
Because the body thinks it can excrete salt fine!
What immediately happens to K as it is ingested?
It is moved into cells using the Na-K pump. Insulin increases its activity.
How does hyperkalemia affect the adrenal gland?
Causes increase in RAAS, aldosterone is a potent stimulus for aldosterone secretion.
K in the nephron
87% is reabsorbed by proximal tubule and loop of henle, but potent secretion occurs at principal cells.
Effect of aldosterone on principal cell
Increases Na reabsorption, increases K secretion, increases activity of basal Na K pump.
How does volume expansion affect K handling?
Volume expansion increases luminal flow, keeps K moving through the lumen.