05.07 - Reg of Body Fluid (Rao) - PP, LG, No reading, Not watched Flashcards
What percent of filtered load of Na is reabsorbed in LOF? DCT/CD?
28%, 7%
What increases ANP
Atrial Stretch; Plasma Pna increase
Renal Na excretory system responds __ to changes in Na input
Relatively slowly
ECFV =
(Amount of ECF Na) / Pna
What ion is lost in diarrhea
HCO3
Where are Neural Stretch Receptors
In large veins
Response to increases in arterial pressure on urinary Na excretion in Isolate Kidney scenario
2-3 fold increase in Na output by 30-50 mmHg change in arterial pressure
Effect of changes in pressure on Na excretion in Isolated Kidney vs Intact System
Takes very large increase in pressure in isolated kidney, but only a very small increase in pressure in intact system
Change in BW over short period indicates
Change in Na balance
3 Actions of ANP
(1) Dilation of Aff, Constriction of Eff - Inc GFR; (2) Inhibit Aldo secretion; (3) Inhibit Na channel phosphorylation in DT/CD
How do burn patients get edema
Inc Endothelial permeability -> Flux of Albumin and Fluid into ISF
Effect of ANP on Afferent and Efferent Arterioles
NPR1 causes dilation of Afferent, but constriction of Efferent -> Inc GFR
Primary Diabetes Insipidus is associated with low plasma
ADH level
ECFV is directly proportional to
Total Body Na content
How do ECF, Sympathetic, Renal Arterial BP affect Renin release
Decreased ECFV, Increased Sympathetic firing, Decreased Renal Arterial BP all increase Renin release from JG Cells
Pna =
(Amount of ECF Na) / ECFV
At constant Pna, ECFV = ____
Amount of ECF Na+
How long does it take to restore water balance after drinking 1 L pure water (change in plasma osmolarity)
1-2 hours
Timeframe of Aldosterone effect on Na reabsorption
Slow, not likely to play a role in rapid regulation of Na excretion
How is Aldosterone release affected by K, Angiotensin, and Na
Release stimulated by plasma K and Angiotensin; Inhibited by plasma Na
How do changes in GFR affect Na excretion
Increase in GFR increases Filtered Load and amount of Na excreted
ANP has exact opposite effect of
Aldosterone
3 causes of Na imbalance
Diarrhea, Excessive Sweating, Diuretics
Change in ECFV in response to Na intake is also
Slow
Receptors for ANP
NPR1/2 - Guanylate Cyclase cGMP mechanism
How does natriuetic hormone affect Na reabsorption
Decreases reabsorption -> Promotes excetion of Na and H20
3 Major “Hypovolemic Hormones”
AVP, Renin, NE
PV determines mean circulatory filling pressure, and therefore __
CO
Effect of Ouabain like factor
Diuresis and Natriuresis
Nephrongenic Diabetes Insipidus is associated with elevated
Plasma ADH
What does the difference in effect of arterial pressure on Na excretion in Isolated vs Intact systems suggest?
Pressure natriuresis is synergized with reduced formation of renin, ang 2, and aldosterone
How does ANP decrease Na reabsorption
In DCT via NCC; In CD via cGMP-mediated ENaC phosphorylation
Timeframe of balance restoration after ingestion of water vs isotonic saline
Water changes osmolarity, 1-2 hours corrected; Isotonic saline increases total Na, 2-4 days corrected
Is sweat isotonic?
No
Is vomit isotonic?
Yes
Change in Pna occurs only when
Gain or Loss of Na exceeds thirst mechanism and kidney’s ability to correct
Activation of Arterial Baroreceptors –>
Pituitary –> AVP
Auscultation signs of edema
S3, Pulmonary Edema
How does Angiotensin 2 Increase Na Reabsorption
Proximal Na:H exchanger
Edema requires ECF increase of
2.3-3 L
Normal Blood Volume? Volume that causes Edema? Death?
15, 20-25, 10-12
Atrial Stretch Receptor Activation –>
Signal via Vagus -> Sympathetic to kidneys, ANP, decreased AVP?
Activation of Neural Stretch Receptors in Large Veins –>
Signals Pituitary to regulate AVP –> NK2C channels in ThickAL
2 Effects of NE
(1) Inc Aff and Eff arteriolar tone -> Dec GFR; (2) Inc Na, H20 reabsorption by proximal tubule
Direct effect of Angiotensin II
Inc Na, H2O reabsorption by proximal tubule
How long does it take to restore balance after 1 L of isotonic saline ingested
2-4 days
More severe increase in ECFV causes
Pulmonary Edema
