Regulation and disorders of salt and water Flashcards
How is total body water (TBW) calculated for both men and women?
Men: TBW = .6 x wt
women: TBW = .5 x wt
How much of total body water is in the ECF?
1/3 of TBW
How much of total body water is in the ICF?
2/3 of TBW
How much of the ECFV is in the ISF?
3/4 of the ECFV
Total body Na+ (TBNa) is synonymous with what?
ECFV
What indicates a change in TBNa?
Clinical signs and symptoms give clues about TBNa
What is the formula for Serum Na?
Serum Na = TBNa/ TBW
T or F: Total body Na+ = Serum Na+
FALSE
Serum Na = TBNa/ TBW
How is sodium balance regulated?
Only by Effective Circulating Volume (ECV)
How and where does Angiotensin II regulate sodium?
Increase Na reabsoprtion
- proximal tubule!
How and where does Aldosterone regulate sodium?
Increases Na+ reabsorption
- Distal tubule!
How and where does ADH regulate sodium?
Increases WATER reabsorption
- distal tubule
Effects of ADH on urine osmolarity?
Increases U osmlarity (concentrates)
- due to increased water reabsorption
What is the effective circulating volume?
- relates to the fullness and tension within the arterial compartment
- usually correlates with total ECFV
When does effective circ. volume not correlates with total ECFV?
- CHF
- Liver disease
- ECF is decreased due to either dec CO (CHF) or arterial vasodilation (splanchnic vasodilation in liver failure)
What occurs if the effective circ. volume decreases?
Angiotensin II: increases
Thirst: Increases
ADH: Increases
=> Na+ retention (RAAs)
=> Water absorption (ADH)