Diffusion and Osmosis Flashcards
simple diffusion is an example of what
passive transport
if there is lower concentration on right and higher on left side of membrane, there is a what
concentration gradient
if there is lower concentration on right and higher on left side of membrane, what direction will solute do
go downhill, towards right.
what is goal of solute
equalize its concentration. it does this by going down concentration gradient until there is none concentration gradient
what factors can affect simple diffusion
concentration gradient*
the level of gradient, it will move faster the biggere the concentration gradient
potassium is 140 inside the cell and 4 outside the cell, which is a gradient for potassium to leave cell. if the potassium outside if 50, what does that mean
less potassium ions will move out of cell, so there is not as great of flux b/c of reduced concentration gradient, so the rate of flux of solute will be affected
draw graph of net flux vs. concentration gradient
pg 10 ppt
What is Fick’s first law of diffusion
J = DA(Ca-Cb)/ ∆X
What does J stand for in Fick’s 1st law of diffusion
flow of solute from region A to region B in the solution
What does D stand for in Fick’s fist law of diffusion
diffusion coefficient of the solute in a given solvent
What does A stand for in Fick’s first law of diffusion
cross-sectional area thru which the flow of solute is measured
if number in denominator is bigger what happens to flux
flux goes down
if number in numberator is bigger what happens
flux goes up
What does Ca-Cb stand for in fick’s first law
the difference in [solute] between regions A & B
What does ∆X stand for in fick’s first law of diffusion
the distance between regions A and B (membrane thickness)
what does membrane thickness do to flux
The thinner the membrane, the more permeable it is to various molecules
what does temperature do to flux
The higher the temperature, the greater the permeability. This factor is rarely important because of the constancy of temperature in the human body
an electrical potential difference across a cell membrane will cause what even if there is not a concentration gradietn
movement of ions
anion on inside, cations outside, where will a negative charged ion go
outside
really high lipid solubility, high
permeability
more lipid a solute is:
faster flux
The thinner the membrane, the more:
permeable it is to various molecules
Name three times that D (the diffusion coefficient) decreases
temp. decreases
size of molecule increases
viscosity of solvent increaes
The smaller the molecule, what happens to permeability?
increases
smaller= more permeable
The larger and more irregularly shaped the molecule, what happens to permeability?
decreases
lower permeability
If there is no concentration gradient, but there is electrical potential, what will happen?
ion will move across membrane
what is the permeability coefficient (P)
includes the membrane thickness, diffusion coefficient of solute within the membrane, solubility of solute in the membrane
what does P stand for
permeability coefficient
what is equation with the permeability coeffieicent
J = PA(∆C)
higher lipid soluble, what will happen via cell membrane
faster it will translocate across cell membrane
the bigger the molecule, what happens to P (permeability)
lower
the harder it is for solute molecule to get across
why does thickness of membrane slow down flux
the solute has to move across more space, takes a long time for it to move across
water will always move in which direction regarding solute concentration
toward highest solute concentration
what is van’t hoff’s equation
pi = nCRT
what does R stand for
ideal gas constant
What does t stand for
absolute temperature
What does C stand for
the molar concentration of solute
what does n stand for
number of ions formed by dissociation of a solute molecule
what does pi stand for
osmotic pressure
always assume cell osmolarity is what
290mOsm/L
75 sodium chloride is how what osmolarity
150 mOsm/L
at physiologic concentrations the molecules can’t do what
completely exert their osmotic pressure
because molecules don’t completely associate they introduce what
osmotic coeffeicient
What does Φ mean
what amount can use its force
what does Φ stand for
osmotic coefficient
what is normal osmolarity range in ECF
275-300 mOsm/L
what is normal cell osmolarity in ICF
300 mOsm/L
every day, intake of water has to equal
outake
how does intake of water equal outake
homeostatic control mechanisms
ADH stands for
anti-diahretic hormon
what does ADH do
you will retain water, won’t urinate as much. thirst mechanism stimulated. try to bring back water balance
define osmolarity
osmolarity in ECF as it relates to cell osmolarity
what is isoosmotic solution
total osmotic presssure of solution is equal to that of the cell
300 outside
what happens to water movement in isoosmotic solution
no water movement
hyperosmotic solution
greater amount of solute molecules oustide the cell
water moves outside cell into ECF
what happens to water in hyperosmotic solution
it moves to ECF
cell volume shrinks
hypoosmotic solution
solute is lower outside than inside cell
water moves into cell
hypo it’s gonna blow
what happens to water movement in hypoosmotic solution
water moves into cell
transient changes happen when in regards to cell volume
first
what is transient change
temporary, not permanent change, responds changes in extracellular concentration of permeant solutes
transient changes caused by
permeant solutes
what is example of permeant solutes
urea
tonicity of solution is determined by what
impermeant solues
what does tonicity determine
steady-state cell volume
isoosmotic solution & isotonic solution
no transient change in cell volume
no change of steady state cell volume
what hypotonicity do you have to have to burst the cells?
if you half the concentration of sodium chloride you will burst 50% of the cells
if cells are super hypertonic what are they called
creamated
what happens when water is added to ECF
ECF & ICF osmolarity & volume and what happens to cell
cells will swell ECF volume: increase ECF osmolarity: decrease ICF volume: increase ICF osmolarity: decrease
what is first thing that is going to hapen when water is added to ECF
ECF expanded
what happens to osmolarity when water added ECF
it decreases b/c more water is added to it diltues it
more water in ECF than ICF what will happen
water will go to ICF, cells will swell
SIADH stands for what
Syndrome of Inappropriate Antidiuretic Hormone Secretion
What happens in SIADH
too much ADHD secreted
ECF diluted
what is hyponatremia
if sodium goes below 135 mEq/L
who is most likely to have hyponatremia
Infants, elderly, military personnel, marathon runners
What is the major determinant of osmolality in ECF?
Na+
What is the major determinant of osmolality in ICF?
K+
if ECF is 140 mM NaCl what is the tonicity?
isotonic
If ECF is 100 mM NaCl what is the tonicity?
hypotonic
If ECF is 180 mM NaCl what is the tonicity?
hypertonic
urea is an example of what kind of solute
permeant
adding urea to ECF will cause what response?
increase ECF osmolality
initially will shrink cells
eventually it will equilibriate across cell membrane - cells back to initial volume
what is a permeant solute
give rise to temporary change in osmotic pressure
what affect does isotonic or normal saline in IV have when added to ECF
fluid will stay in ECF b/c it’s isotonic, ultimately it expands ECF
What are the affects to ECF & ICF volume & osmolarity when isotonic/normal saline are added
ECF volume: increase ECF osmolarity: no change ICF volume: no change ICF osmolarity: no change
what affect does adding hypertonic saling to ECF have?
osmolarity greatly increases initially
fluid drawn out of cells
cells srhink
what are affects to ECF & ICF volume & osmolarity when hypertonic saline to ECF is added
ECF volume: increase ECF osmolarity: increase ICF volume: decrease ICF osmolarity: increase
anytime concentration of sodium is less than 135 mEq/L what is it
hyponatremia
hyponatremia, what is happening
too much water in ECF so diluting electorlight
describe SIADH
too much ADH - too much water, will dilute electorlites
what is normal saline
140-145 mM (or round to 150)
when would you give hypertonic saline
when you want water to move out of cell - pt has very low sodium (hyponatremia)
in hypotonic solution what is happening
less sodium chloride than normal so water goes into cell, cell swells
what does RVI stand for
regulatory volume increase
what does RVD stand for
regulatory volume decrease
if cell swells what mechanism is put in place
RVD
if cell shrinks what mechanism is put in place
RVI
RVD mechanism - what happens
solutes go out, so potasium, Cl- etc will leave cell so water follows
what feedback mechanism is RVD
negative feedback mechanism so volume goes back to normal
in RVI what happens
solutes go into cell so water follows
so K+, 2Cl, Na+ etc goes into cell
for RVD what is the main solute moving
mainly potassium transport
for RVI what is main solute moving
mainly sodium moving
what is decreased skin turgor
skin isn’t flexible
