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23 Cards in this Set
- Front
- Back
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Water transport as described through the kidney
glomerular filtrate: where is it reabsorbed in the kidney? how do membranes acheive selectivity through permeability? |
in the proximal tubule and
in the descending thin limb epithelial cells through aquaporin-1 (AQP1) permiability selectivity: aquaporins |
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how does the Hormone vasopressin increase membrane water permeability ?
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stimulates redistrubution of AQP2 from cytoplacmic vesicles to apical membrane of PRINCIPLE cells
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AQP-1
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monomer
congegrates as tetramer? but water slides down each monomer 6 mem spanning helices loops B and E loop into membrane and form the pore NPA motifs water can move in both directions water is just the right size to fir, an arg and a his keep H+ from going through, only water selectivity without loosing rapid exchange |
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osmosis
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net flow of water across a membrane
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osmotic pressure
definition what provides osmotic pressure in a cell? |
driving force for osmosis
the pressure needed to prevent movement of water from a place of low solute to a place of high solute in a cell the SOLUTES provide osmotic pressure |
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what does osmotic pressure depend on?
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the osmolarity of solutes
the permeability of membrane to solutes |
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osmolarity
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Osmolarity measures the gradient for water assuming all the osmotic solute is impermeant. It is simply a count of the number of dissolved particles. Therefore a 300 millimolar solution of glucose, a 300 millimolar solution of urea, and a 150 millimolar solution of NaCl each have the same osmolarity.
colligative property |
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colligative property
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depends on total number not the nature/size/charge
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osmolarity
eqn |
g(# of particles/mole)
/ C ([]mmol/L) more solutes = more osmolarity |
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hyperosmotic
hypo-osmotic iso-osmotic |
hyper - higher osmolarity
hypo- lower osmolarity iso - 300 mOSM is standard intracellular osmolarity |
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reflection coefficient
of 0 of 1 ex for each |
describe ease of solute passage through membrane
0 - freely permeable, solute exerts no osmotic pressure/no driving force urea is close to zero 1 - impermeable, provides osmotic pressure across the membrane ie serum albumin/ions/proteins etc |
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vant hoff eqn
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described osmotic pressure of a solution
SEE pg 211 |
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tonicity
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biological property
dependant on concentration of impermeable solute Tonicity is a functional term that describes the tendency of a solution to resist expansion of the intracellular volume. osmolarity * reflection coeff hypoTONIC solution causes cell to swell hyperTONIC solution causes cell to shrink |
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what happens if you add more NaCl to an iso-tonic solution into ECF(extra cellular fluid)?
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cell swells . . .
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SEE PAGE 213!
AQP disease |
hf
AQP2 protein may be involved in most water imbalances Diabetes insipidus results in vasopressin which causes channels to be open all the time? |
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Van't Hoff
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1 osmolarity - [] of osmotically active particles. only dependent on total # of particles
gC (particles per molecule/ 2 reflection coefficient |
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mM vs mOsm, calc osmolatiry
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100mM urea 100mOsm
100mM NaCl 200mOsm 200mM CaCl2 600mOsm |
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isoosmotic
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two solutions have the same osmolarity
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hyper osmotic
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higher than 300 mOsm
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hypo osmotic
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lower than 300 mOsm
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reflection coeff
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ease through which [articles pass through the plasma mem
no go = 1 proteins good to go = .2 urea |
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NOTE
CELL IS ALWAYS PLACED IN AN |
INFINITELY LARGE BATH. volume of cell cant change the volume of the surrounding solution
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150mM NaCl
100mM NaCl 300mM urea |
means 300mOsm means isotonic
means 200mOsm means hypoosmotic, hypotonic(water is going in) 300mOsm - isoosmotic, hypotonic! urea will go into cell by diffusion to achieve [] balance, where solutes go, water will follow, thus the cell swells |
