IRAT 3 Flashcards
movement of water across membrane in response to a solute concentration gradient
osmosis
characteristics of a solute
-nonpenetrating
-osmotically active
these 2 things guarantee osmosis will occur
osmotically active
solute can draw water - make it move
- molecule has charge/residues
osmolarity
g/v unit of concentration of solute
- concentration of osmotically active ions
is osmolarity static or no?
yes
tonicity
fluid thing, water is moving or moved or is about to move
iso-osmotic
have same number of particles
same osmolarity
what can you conclude from 2 fluid bags from different countries but both 360 mOsm/L
iso-osmotic
what can you conclude from 2 fluid bags - one is 300mOsm/L and another 360mOsm/L
the 300mOsm/L is hyposmotic to the 360 and the 360 is hyperosmotic to the 300
normal human cells have an osmolarity of…
300
osmolarity of 5% Dextrose
260 mOsm/L
osmolarity of 0.9% NaCl
300mOsm/L
osmolarity of 10% Dextrose
520mOsm/L
osmolarity D5NS
560 mOsm/L
total body water is a ratio of what
ICF to ECF
2/3 TBW =
ICF
1/3 TBW
ECF
ICF
cations K+ and Mg2+
anions = proteins and organic phosphates
ECF
interstitial fluid and plasma
major cation = Na+
major anions = HCO3 and Cl
plasma of ECF
25% ECF
albumin and globulins
lots of proteins
interstitial fluid localized to blood
interstitial fluid of ECF
75% ECF
lower proteins than ICF
fluid between cells - all cells in body
isotonic volume expansion
consumption of large volume of isotonic solution
ex: sugar free gatorade excess consumption - taking it into body and not isotonic blood volume increases
isosmotic volume contraction
diarrhea
loss of isotonic fluid
losing liquid and not replacing it
hyperosmotic expansion
excessive NaCl intake
osmolarity of ECF inc and ICF dec
ex: eating wings at a bar
hyperosmotic volume contraction
dehydration
osmolarity of ECF inc and ICF dec
ex: person in desert with no water- just losing fluids but also sweating a lot
changes in ECF volume affect
effective circulating volume (blood flow/blood volume)
why do we give IV solutions
quickly expand IVV (intravascular volume)
correct or compensate for fluid, electrolyte, acid-base imbalance (direct or indirect)
isotonic saline infusion
normal saline = 0.9%, 300mOsm/L
higher ECF and similar ICF
5% Dextrose infusion 260mOsm
hyposmotic
ECF volume expansion
inc ICF
ineffective means of inc ECF bc sugar draws water away
5% NaCl
hyperosmotic
inc ECF osmolality
dec ICF volume
1500 mOsm - can damage blood vessels, only given this in really bad shape
charged particles in solution NOT proteins or large particles
ex: K+, Ca2+, Mg2+, Na+, Cl- dissolved in water
electrolytes
colloids
large charged particles in solution
-colloidal suspensions used in fluid replacement therapy
-large molecular weights
in water, must have CHARGE associated with them
Albumin
#1 largest molecular weight compound in blood (plasma) the majority function of all large MW things in blood plasma = 85% water, the rest is albumin mostly
what 2 forces in the body make fluids move from inside capillary to outside or otside capillary to inside?
hydrostatic pressure
osmotic pressure
what happens at capillaries and what is their structure?
gas exchange, nutrients vs waste, heat exchange, hormones
action in tissues happens here
simple squamous epithelium (single layer cells)
increased surface area
what is the hydrostatic force in tissue
interstitial fluid
hydrostatic P in capillaries is a reflection of what?
blood pressure
Pint
interstitial hydrostatic pressure outside the bloodstream
P bc fluid in interstitial space and there is a layer protecting it (skin)
sum total of all osmotic particles in the interstitial fluid
interstitial osmotic volume
aka oncotic
oncotic
represents the magnitude of P associated with presence of proteins (large MW proteins)- colloids
proteins are doing the osmosis
what 2 forces are outside the blodstream
Pint and oncotic
(pi)int
osmotic P due to the presence of proteins
what is an osmotic force?
draws water from capillaries out into interstitium bc charged particles can draw water
hydrostatic P favors fluid exit or entry from capillaries?
favors the entry of fluid into capillaries
force pushing down on capillary
(pi)cap
oncotic P in capillary
draws fluid into capillary
what is the #1 contributer to (pi)cap?
albumin!!! - made in the liver
Pcap
hydrostatic P in capillary
force goes in to out
is there smooth muscle in capillaries? why or why not?
NO
it is simple squamous epithelium (one layer of cells)
