Physio 1 Flashcards
what happens to body fluid as you age?
decreases from approx 75% of weight in newborns to 50% in aged adults. extracellular fluid goes from 50% to 33%
relationship between total body water and body fat
inversely proportional.
body fluid balance
the kidneys maintain and monitor plasma volume and osmolarity which in turn maintains total body water and osmolarity due to water and solute exchange between ECF and ICF compartments
what does unregulated water and salt loss from TBW occur through?
sweat, feces, and insensible skin and lung loss (H20 only)
what drives fluid distribution between plasma and interstitial fluid?
balance between hydrostatic pressure and osmotic pressure differences across the capillary wall. depends on starling forces.
filtration or reabsorption rate formula
Lp [(Pc-Pi)-(piC-piI)]
solute distribution
similar between ISF and plasma with exception of negatively charged plasma proteins, which are impermeable to the capillary wall and remain within the intravascular compartment. accordingly, osmotic pressure is higher in plasma than ISF due to the absence of protein in the ISF
edema
excess accumulation of fluid in the interstitial space due to cardiac, renal, hepatic, or endocrine dysfunction
regulatory functions of the kidneys
extracellular fluid volume, fluid osmolarity, and fluid ion composition. clearance of metabolic end products, toxins, and drugs. endocrine functions such as erythropoietin, active vitamin D, and renin
isosmotic fluid expansion
intravenous isosmotic fluid gain to ECF
what happens to ICF and ECF volume and osmolarity when a volume of isosmotic solution is added to ECF?
intravenous isosmotic fluid gain to the ECF
what happens during isosmotic volume contraction?
diarrhea, isosmotic/isotonic fluid loss from the ECF
what happens during hyperosmotic volume contraction
profuse sweating and water deprivation (loss of water in excess of solute from the ECF)
what happens during hyperosmotic volume expansion?
high NaCl intake without fluids, gain of solute in excess of water in the ECF
what happens during hypoosmotic volume expansion
syndrome of inappropriate antidiuretic hormone (SIADH) - gain of water in excess of solute in the ECF. an inappropriate excess of circulating ADH causes an increase in water reabsorption from the renal tubule into ECF
what happens during hypoosmotic volume contraction
adrenal insufficiency and decreased renal NaCl reabsorption (loss of solute in excess of water). aldosterone insufficiency iresults in decreased return of NaCl to the ECF
what happens during hypoosmotic volume contraction
adrenal insufficiency and decreased renal NaCl reabsorption (loss of solute in excess of water). aldosterone insufficiency iresults in decreased return of NaCl to the ECF
cell volume regulation
cells use solute transport mechanisms to change ICF volume.
cell shrinking in response to an increase in ECF osmolarity
cells activate solute uptake mechanisms to increase ICF osmolarity, driving water into cells (regulatory volume increase RVI)
cell swelling in response to a decrease in ECF osmolarity
cells activate solute efflux mechanisms to decrease ICF osmolarity driving water out of cells to restore volume to normal
basic renal filtration
separation of an ultrafiltrate from the blood. done through glomerular capillaries
basic renal reabsorption
directional movement of solutes and water from the lumen of the kidney tubule to the peritubular surface (blood side)
basic renal secretion
directional movement of solutes from the peritubular side of the kidney tubule to the lumenal surface
basic renal synthesis
metabolism within kidney cells degrading and creating organic solutes or hormones appearing in the blood or in the urine
