Renal Physiology Flashcards
1
Q
Equation for Plasma Na
A
TBNa/TBW
*plasma Na concentration depends on total body sodium over total body water
2
Q
AVP/vasopressin/ADH - where’s it released and where it acts
A
- released from neurons in supraoptic and paraventricular nuclei in the hypothalamus in response to high plasma concentration/osmolality
- act by binding the V2R and V1aR (vasopressin receptors)
- V2R in TAL, DCT, and CD (principal cells) - cause increased AQP2 expression (short-term expression and long-term transcription) and thus inc. water reabsorption
- V1aR in vascular smooth muscle, causes contraction
- much lower threshold for osmolality than volume to stimulate ADH secretion
3
Q
Free water clearance is positive when…
negative when…
A
Positive: hypotonic urine (dilute plasma, get rid of extra water)
Negative: hypertonic urine (concentrated plasma, keep the water)
4
Q
Osmolar clearance (Cosm)
A
can think of it as the minimum water needed to clear the solutes that must be excreted; can increase with use of osmotic diuretics, increased solutes (like inc. [bicarb] when been vomiting, increased salt intake, or inhibited NaCl reabsorption)
