Renal Physiology Review Flashcards
Fluid components highest in ECF
Na+
Cl-
HCO3-
Ca2+ (slightly)
Fluid components highest in ICF
K+
Organic anions
Protein
Mg2+
Protein levels are highest in the ____ and ____ compartments; membranes are impermeable to proteins so they don’t normally impact osmolarity but do exert _______ pressure
ICF; vascular; oncotic
Indicators used to measure TBW, ECF, and Plasma Volume
TBW = 3H2O, 2H2O, antipyrine
ECF = 22Na, 125-iothalamate, thiosulfate, INULIN
Plasma volume = 125I-albumin, Evans blue dye [albumin can be used because it should not cross PMs]
ICF and ISF are not measured directly. How are they calculated?
ICF = TBW - ECF
ISF = ECF - plasma
ECF osmolality is driven (primarily) by ___ and ____
ICF osmolality is primarily driven by _____
Na+; Cl-
K+
ICF, ECF, and osmolality changes with diarrhea, vomiting, or hemorrhage
ECF volume: decreases
ICF volume: no change
Osmolality: no change
[isosmotic volume contraction]
ICF, ECF, and osmolality changes with dehydration
Depends on the cause!
Isosmotic dehydration caused by hemorrhage, burns, vomiting, diarrhea, hemorrhage — ECF decreases, no change in ICF or osmolality
Hyperosmotic dehydration caused by decreased fluid intake, diabetes insipidus, diabetes mellitus, fever — ECF decreases, ICF decreases, osmolality increases
Hyposmotic dehydration caused by adrenal insufficiency (e.g., Addison’s disease) — ECF decreases, ICF increases, ECF osmolarity decreases
ICF, ECF, and ECF osmolarity changes with diabetes insipidus
ECF volume: decreases
ICF volume: decreases
ECF osmolarity: increases
ICF, ECF, and ECF osmolarity changes with hypoaldosteronism
ECF volume: decreases
ICF volume: increases
ECF osmolarity: decreases
ICF, ECF, and osmolality changes with diabetes mellitus
ECF volume decreases
ICF volume decreases
ECF osmolarity increases
ICF, ECF, and ECF osmolarity changes with SIADH
ECF volume: increases
ICF volume: increases
ECF osmolarity: decreases
What happens to RBCs placed in isotonic, hypotonic, and hypertonic solutions?
RBC in isotonic = no change
RBC in hypotonic = cell swells
RBC in hypertonic = cell shrinks
Acute and chronic changes in renal blood flow and GFR caused by increased angiotensin II synthesis
RBF decreases
GFR increases
Acute and chronic changes in renal blood flow and GFR caused by increased release of ANP
RBF: increases
GFR: increases
Acute and chronic changes in renal blood flow and GFR caused by decreased prostaglandin formation
RBF: decreases
GFR: no change/decreases?
Effect of sympathetic stimulation on RBF, GFR, renin secretion, and proximal tubular Na+ reabsorption
RBF: decreases
GFR: decreases
Renin secretion: increases
Proximal tubular Na+ reabsorption: increases [less is excreted]
List factors that regulate secretion of aldosterone
Renin Angiotensin II (increases aldosterone secretion)
Physiological effects of RAAS [actions of aldosterone]
Increases Na+ reabsorption
Increases K+ secretion
Increases H+ secretion
Effects of sympathetic nerves on regulation of Na+ reabsorption along the nephron
Sympathetics nerve stimulation —> increased NaCl reabsorption at PT, TAL, and DT/CD [PT most important site of action]
Alterations in Na+ reabsorption with hypovolemia
Integrated response to decreased ECV:
GFR decreases —> increased Na+ reabsorption by proximal tubule, loop of henle, distal tubule, and collecting duct
Water reabsorption is enhanced
Alterations in Na+ reabsorption with hypervolemia
Integrated response involves:
Increase in GFR —> decreased reabsorption of Na in proximal tubule, loop of henle, distal tubule, and collecting duct
Water excretion follows
Effect of angiotensin II on regulation of Na+ reabsorption along the nephron
Angiotensin II —> increased NaCl reabsorption at PT, TAL, DT/CD
Effect of aldosterone on regulation of Na+ reabsorption along the nephron
Aldosterone —> increased NaCl reabsorption at TAL, DT/CD
Effect of ANP on regulation of Na+ reabsorption along the nephron
ANP —> decreased NaCl reabsorption at CD
What change in fluid balance would you expect if you ate a high NaCl diet for 2 weeks?
ECF/Interstitial fluid volume increases
[same effect as hyperaldosteronism aka Conn’s dz]
A decrease in the GFR, RBF, and peritubular capillary hydrostatic pressure indicates constriction of the afferent arteriole. If there was also a rise in oncotic pressure in the peritubular capillary, it is an indication that the filtration fraction has increased. What does this mean for constriction vs. dilation of the efferent arteriole?
The efferent arteriole is constricted [plasma flow dropped more than the GFR indicating the efferent arteriole also vasoconstricted]
With diabetes insipidus, there is ______ free water clearance and excretion of _____ is elevated
Positive [dilute urine]; potassium [d/t elevated aldosterone]
Changes in sympathetic tone, plasma angiotensin II levels, ANP levels, and plasma oncotic pressure as a result of dehydration d/t severe diarrhea
Sympathetic tone increases
Plasma angiotensin II levels increases
ANP levels decreases
Plasma oncotic pressure increases
Changes in aldosterone, ANP/BNP, angiotensin II, and ADH levels with CHF
Aldosterone levels increase
ANP-BNP levels increase
Angiotensin II levels increase
ADH levels increase
What changes in TBW, ECF osmolarity, ECF volume, ICF osmolarity, and ICF volume would take place if a dehydrated individual replaced all their fluids with pure electrolyte-free water?
TBW: no change ECF osmolarity decreases ECF volume decrease ICF osmolarity decrease ICF volume increase
