Regulation of Sodium and Water Balance - McCormick Flashcards
How is plasma sodium regulated?
Primarily in changes in water balance
-same as osmolarity
3 Factors that promote sodium reabsorption?
Renal sympathetic n
RAAS
Aldosterone
3 Factors that promote Na excretion
ANP/BNP
Urodilatin
Prostaglandins
What happens with increased renal sympathetic nerves?
Could be caused by fall in perfusion
- Decreased GFR
- Increased proximal Na and H2O
- –these 2 lead to decreased fluid to MD - Direct stimulation of granular cells
- -these 3 lead to increased renin secretion
What are the effects of Ang II?
Systemic vasoconstriction Efferent > afferent (decreased RBF) constriction Na+ reabsorption Thirst ADH (post pit) Aldosterone (adrenal cortex)
What are aldosterones actions in late DCT/CD?
Stimulates Na reabsorption
Potassium and H secretion
Factors controlling aldosterone secretion
Increased plasma K conc
Volume depletion
ANP effects
Increased GFR - aA dilation and eA constriction
Suppresses renin, aldosterone, AVP
Systemic vasodilator
There is an increased ECF volume, ANP response?
Increased ANP - this leads to increased medullary blood flow and GFR
Decreased Renin, Ang II, Na reabsorption
Characteristics of urodilatin
Secreted by DCT/CD in response to increased arterial pressure and ECF volume
Suppresses Na and water reabsorption
NO systemic affect
What do intrarenal prostaglandins do?
Increase Na excretion
Increase GFR (dilate arterioles)
Suppress Na reabsorption in TAL/CD
What are the two major stimuli for ADH release?
Hyperosmolality
Volume depletion
-hypothalamic osmoreceptors > hepatic
You are tired, you’ve been studying all day. You head home, turn on Netflix and open a bag of Ruffles. One season of the Girls Next Door and you are on your third bag of chips. What happens in the body?
Increased ECF Increased ANP secretion Decreased RAAS Decreased NaCl reabsorption Increased NaCl excretion in urine
Hyponatremia
Too much water
Low plasma Na
Hypernatremia
Too little water
High plasma Na
Edema
Too much Na
Volume depletion and Na content
Too little Na
Student Doctor, Stew Bro, has decided to reenact the scene in Vampire Diaries where all of the people die. Josh, his fellow vampire aficionado, slips on a dirty sock and accidentally stabs Stu in the throat. As blood spurts everywhere, what happens to the activation of Ang II in Stew’s nearly lifeless ethnically ambiguous body?
Decreased arterial pressure
This leads to increased activity of renal symp nerves and RAAS
Ultimately leads to decreased excretion of sodium and water
