Fluid and Electrolyte part 3 Flashcards
What is hydrostatic pressure?
pushes water out of vascular system into interstitial space (like in hypovolemia)
What is oncotic (colloidal osmotic pressure)?
pulls fluid from tissue to vascular space
What fluid is used to fix hypovolemia?
isotonic: 0.9% NaCl or lactated ringers
What is edema or second spacing and how is it similar to hypovolemia?
plasma to interstitial fluid shift
What is third spacing (ascites)?
fluid trapped where it is difficult or impossible for it to move back into cells or blood vessels
What is diffusion?
movement across a permeable membrane from high to low concentration
What is facilitated diffusion?
uses a protein carrier
What is active transport?
molecules move against (with ATP) the concentration gradient
What is osmosis?
- water moving down the concentration gradient
- from low to high concentration
- osmosis and diffusion are opposites
What is a normal plasma osmolality?
280 and 295
What is a plasma osmolality of greater than 295?
water deficit and concentration of solute is too high
What is a plasma osmolality of less than 275?
water excess
concentration of solutes is too low
What is ADH stimulated by?
- low Na+
- low blood volume
- low body fluid
- increased osmolarity (water deficit) of body fluids (concentration)
- ADH tells us to drink water!
What suppresses ADH release? and why?
-decreased plasma osmolality (water excess) suppresses ADH because ADH tells us to drink but if we have a fluid excess we don’t want to drink
What is the primary organ of fluid and electrolyte balance?
kidneys: renal tubules are the site of ADH and aldosterone
