11.3: {Na] Flashcards
1
Q
What is blood [Na] equal to?
A
Total body Na / Total body water
2
Q
What does water excess w/o change in body Na Cause?
A
Hyponatremia
3
Q
How does body respond to increased water intake?
A
- [Na] drops
- Decrease thirst and ADH release
- Increased renal excretion and decreased thirst normalize
4
Q
Other names of ADH?
A
- AVP
- Vasopressin
5
Q
ADH action?
A
- Produced by hypothalamus stored in post. pit.
- Acts on distal tubule increase H20 resorption
- Leads to increase urine []
- Causes constriction as well
6
Q
Definition of concentrated urine?
A
- Urine osmolality > plasma
- Plasma osmolality usually 300
7
Q
How is ADH regulated?
A
- Increased osmolality increased ADH release
- Larger decrease in V. or P. leads to release
- P and V can overcome osmolality
8
Q
ADH more sensitive to osmolality or P and V?
A
- Osmolality
9
Q
% of body weight that is salt water?
A
60%
10
Q
What is SIADH?
A
- Syndrome of Inappropriate ADH
- Increase body water with normal [Na]
- Tumor producing ADH
11
Q
What is a water pill?
A
- Diuretic
- Tells body to get rid of salt and water
12
Q
What can cause hyponatremia?
A
- SIADH
- Diuretic use with water intake
- Increased TBW and smaller increases in Na
13
Q
Why is hyponatremia solely from fluid ingestion rare?
A
Body can create extremely dilute urine by using close to no ADH
14
Q
What is hyponatremia usually due to?
A
- Impaired renal water excretion
1. Impaired dilution due to excess ADH
2. Intrarenal factors - Might be ingesting high volume and low solute: beer drinks syndrome, but this is rare
15
Q
Can body produce pure water?
A
- No, some Na must be secreted with water
- 50 is lowest body can go
- If you have high water intake and low osmolar intake
- You will pee out all your osmoles
16
Q
Intrarenal factors leading to hyponatremia?
A
- Renal failure (decreased GFR)
- Diuretics preventing resorption in distal tubule to create free water
- Solute avidity in prox tubule (CHF) must be able to deliver solute to distal
