fluid changes with age
osmosis
water moves from high water concentration to low water concentration
diffusion
particles move from high particle concentration to low particle concentration across semi-permeable membrane
active transport
ATP requires
Na-K pump
regulation of fluid balance
antidiuretic hormone (ADH)
nervous system regulation of fluids
baroreceptors sense change in pressure and decrease in CO —> SNS increases HR resulting in peripheral vasoconstriction —> vasoconstriction in renal arteries results in decreased glomerular filtration, decreased urine output and increased BV
increase HR for vasoconstriction to decrease urine output and increase BV
renin-angiotensin-aldosterone
H2O follows…
Na
cortisol
kidneys
tonicity
- determines where fluid will go
tonicity categories
isotonic IV solutions
normal saline
0.9% NaCl
ringers lactate
closest to plasma
2/3 & 1/3
2/3 dextrose 1/3 saline
hypertonic IV solutions
D5S
5% dextrose in N/S
D5 1/2 N/S
5% in 0.45% N/S
total parenteral nutrition
- very hypertonic solution
hypotonic IV solutions
forces within capillaries
- osmotic/colloid pressure
hydrostatic pressure