OSMOSIS

is osmosis the flow of solvent or solutes?

SOLVENT

Place cell in pure water

VERY HYPOtonic

n =

number of particles the solute dissociates into (1 for nonelectrolytes, 2 for NaCl, 3 for MgCl2)

why do cells survive when they're constantly at risk of bursting?

1. Na/K pump is constantly pumping Na out of the cell = effectively impermeable! 2. the na ions try to draw water out of the cells by osmosis, & this balances the tendency of water to move into cells 3. energy (ATP) is required to run the pump

Most important impeameable solutes:

1. cytoplasmic proteins in the cell 2. extracellular Na+ enters the cell but is pumped back out again by the Na+ pump, so it's considered "functionally impermeable" 3. other extracellular solutes, like sugar * impermeable solutes tend to draw water into cells via osmosis = puts animal cells at risk of bursting!

2 levels of physiology that osmosis is important in

1. movement of water across a cell membrane = maintain cell shape and size! 2. movement of water through multicellular structures = capillaries/alveoli

sodium chloride is impermeable to a cell, so it's o =

1.0 !!

what's the normal osmolarity of plasma?

280 & 300 OsM

if a solute is PARTIALLY PERMEABLE , o =

< 1.0 ; hyposomotic & hypotonic = CELL SWELLS

osmotic pressure differences cause water to move through pores in a membrane just like the _____ pressure would

HYDROSTATIC Q = water flow Q = Lp delta P Lp= filtration coefficent delta P = net driving force from hydrostatic and osmotic pressures * used in studying the movement of water in& out of capillaries in cardiovascular and renal section of physiology

290 mM NaCl

HYPER tonic

reduce swelling of brain??

HYPERTONIC

580 mM sucrose

HYPERtonic (cell shrinks)

a solution with a lesser osmolarity is

HYPOosmolar

145 mM sucrose

HYPOtonic (cell will swell)

place cell in 290 mM of sucrose (impermeable to cell)

ISOTONIC

what type of fluids should be consumed follwing aerobic exercise?

ISOTONIC

T =

Kelvin temperature (273 + celsius)

applying pressure to the piston is equal to

Osmotic pressure = stop flow

permeable particles cause only ___ changes in cell volume

TRANSIENT

how do we determine osmotic pressure difference when solutions are dilute & the membrane is absolutely impermeable to solute:

VAN'T HOFF EQUATION osmotic pressure = nRTdeltaC * ASSUMES THAT NO SOLUTE CAN CROSS THE MEMBRANE!

580 mM urea

VERY HYPOtonic!

partially permeable solutes , so the actual osmotic pressure would

be between 0 & pressure predictred by van't hoff law

What is the result of movement across cell membranes

changing cell volume = shrink/swell/burst! * cell membrane is the regulator!

steady-state volume is determined by

concentration of impermeable particles in the the ECF

delta C =

difference in molar concentration!

Diffusion means ___ in the phospholipid bilayer, whereas osmosis means ____ _____ membrane pores (aquaporins) as hydraulic flow

dissolving moving through

origin of ankle edema?

excess fluid!!

how is osmolarity typically measured??

freezing point depression

what causes xs urine flow in diabetics??

glucose in plasma draws water into urine via osmosis

a solution with a greater osmolarity is

hyperosmolar

where is osmosis by movement of water through multicellular structures important?

in organ system physiology, where sheets of cells are treated as membranes & osmotic pressure & osmosis of water are important phenomena EXAMPLES: endothelial cells of capillaries in all tissues epithelial cells lining GI tract epic cells making up walls of kidney tubules IMPORTANT IMPERM SOLUTES: - plasma proteins (understand mvmt of water in and out of caps) - various ones in the gut & kidney tubules

if two solutions have the same osmolarity they are ___

iso-osmotic

cell in hypertonic solution??

it shrinks

cell in hypotonic solution?

it swells

the tonicity of a solution refers to ______

long term steady state volume of a cell & depends on the ____ concentration of IMPERMEABLE solutes

what happends to a cell if it's placed in an ISOTONIC solution?

maintains it's volume

Osmotic pressure

minimum pressure that needs to be applied to a solution to prevent INWARD flow of water across a semiperm membrane

the osmotic pressure of a single solution can be defined as

osmotic pressure = nRTC so, solutions of a higher concentration, HAVE A HIGHER OSMOTIC PRESSURE!

what does van hoff't quantitate?

osmotic pressure across a membrane

When the reflection coefficient is less than 1

osmotic pressure difference is smaller & it dissipates over time!- - also means that the solute will eventually diffuse across the membrane & reach equilibrium * initial osmotic pressure differnce will gradually dissipate

what is a membrane called if it lets a solute pass as easily as water?

permeable & there will be diffusion

what is a set-permeable membrane?

permeable to water, but impermeable to solute!

Osmolarity is _______ property of a solute

physiochemical

Reflection Coefficient

relates to how a semipermeable membrane can reflect solute particles from passing through if it = 0 => all particles can pass through! if it = 1 => no particles can pass through = IMPERMEABLE if it = 0.2 => it will eventually find it's way to the other side of the membrane! ** ALWAYS BETWEEN 1 & 0!

relative impermeability

solute can slowly pass through a membrane, although much slower than water can " use reflection coefficient"

similarities between osmosis & diffusion

spontaneous processes (arise from random molecule movements) -mechanisms where the net flow of matter is from high to low concentrations *The direction of both processes to abolish concentration differences!

what is osmolarity ?

the concentration of particles in the solution

tonicity definition

the concentration particles OUTSIDE the cell that cannot cross the membrane

what does osmotic pressure depend on?

the difference in total number of particles per unit volume! { 0.15 M NaCl exerts as much osmotic activity as 0.3 M sucrose}

what is osmosis?

the diffusion of water through a semi-permeable membrane! *functions like salt balance in fish, kidney function, and conc of solutes in IVs

definition of Osmosis

the flow of water through a semi-permeable membrane, from a compartment where the solute conc is lower to the side of the mem where the solute concentration is higher * water flows from a region of higher water concentration to the side with lower water concentration

R =

universal gas constant (.08205 L * atm/mole * K)

290 mM urea

urea easily crosses the membrane = HYPO tonic

direction of flow

water flows from low solute concentration to a high solute concentration

how can you determine the diffusion coefficient of WATER?

water flux measured by diffusion of titriated water ; permeability of THO in membranes are in line with those of other small hydrophilic solutes

Solvent Drag

when water is moving across a multicellular membrane via osmosis, permeable solutes are caught up in the flow & DRAGGED ALOng

can a membrane be permeable to one solute, but impermeable to another solute, in the same solution?

yes!

Does osmosis need a membrane to take place??

yes! it ONLY takes place if a membrane is present