Flashcards in Regulation of Sodium Balance and Extracellular Fluid - Rao Deck (20):
What is ECFV proportional to?
Total body Na content
What are the ways that Na is excreted from the body?
Skin (0-20%) - sweat (half isotonic)
GI - (.5-10%) - diarrhea, vomiting (isotonic)
What are common causes of Na imbalance?
What are the locations and amounts of renal Na reabsorption?
PT - 64% (isotonic)
LoH - 28%
DT / CD - 7%
What are signs of a decrease in ECFV?
Hypotension / Orthostatic hypotension
What are signs of an increase in ECFV?
Pulmonary edema (more severe)
Heart sounds (S3)
Jugular vein distension (JVD)
What can cause edema with normal or low ECFV?
How quickly does the body react to changes in plasma osmolarity?
How quickly does the body react to changes in Na intake?
What receptors regulate ECFV, where are they located, and what is their mechanism?
Neural stretch receptors - large veins - signals pituitary to regulate AVP/ADH
Atrial stretch receptors - atria - parasympathetic in vagus for AVP secretion - sympathetic firing to kidneys and cardiovascular
Arterial baroreceptors - arteries - signals pituitary to secrete AVP
What mechanisms regulate Na excretion?
How does arterial pressure regulate Na excretion?
Reduced Angiotensin II
Where does aldosterone act and what are its actions?
DCT and CD
Increases Na reabsorption
*Relatively slow effect
Where does natriuretic peptide (ANP) act and what are its actions?
Renal tubule - inhibits Na reabsorption
Renal vessel - increase GFR / Na excretion
Adrenal cortex - inhibit aldosterone
Described the renin-angiotensin system (RAS).
Stimulation - decreased ECFV, BP or increased sympathetic firing
JG cells - alpha 2 globulin -> AT I
Lungs - AT I -> AT II via Angiotensin converting enzyme
Adrenal cortex - increase Aldosterone
AT II - increase proximal Na:H exchanger
How do sympathetic nerves affect Na reabsorption?
Increase proximal reabsorption
Where are prostaglandins, bradykinin, and dopamine produced and how do they affect Na reabsorption?
Diuresis / Natriuresis
Where is ouabain like factor produced and what is its affect on Na reabsorption?
What are the hypovolemic hormones?
Renin (->AT II-> Aldosterone)