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3-water diffusion (9 oct) (desc: (Isoosmotic solution: Has the same…

- - - - 300 mM solution of urea:
        osmolarity 300mOsmoles/L
        
        does not dissociate in water
      - 150 mM NaCl : 300 mOsmoles/L
        
        DISSO. in water:
        we have sodium particle and cl particle
        
        osmolarity of solution is twice its conc.
        
        e.g 1M glucose = 1 osM,
        1M NaCl = 1 osM Na+ & 1osM Cl- in solution = 2 osM
- - - - Particles include any ions such as Na+, Cl and
        Ca2+
        and any molecules such as glucose or amino acids.
    - - osmolarity infuences:
        
        conc. of solute
        
        conc. of water
        
        water will move from the area of high con. to low conc.
- - - - water difus.
        from low os
        to high os
- - - - allows rapid diffus.
        of this polar molecule across memb.
        
        because of the presence of aquaporin
        we get the difusion of water
        changes in cell volume:
        situation of differences in osmolarity
        
        highly specific for water molec
        increase the rate of difusion of water molec. by 10x
        bidirectional
    - - Membranes have channels to allow certain molecules to
        break the rules
- - - - osmotic force: drive water down its conc. grad.
    - - the difu. of water=osmosis is continue to occure until the build up of hydrostatic pressure is equally opposite to the osmotic pressure that driving the fluid in the opposite direction
        
        final situ: dynamic equlibrium
        still tendency for watr to diffu. down its conc. gradient(osmotic force)
        it is balanced by the increase in hydrostatic pressure>>> forcing the water in the opposite direction
        
        pressure associated with the mov. of water can be large:
        
        1 osmol per liter difference in osmolarity= 22.4 atm pressure:
        massive amount of pressure
        
        cytoplasm= 300mOsmoles/L
        
        put a cell in pure water:
        bacause of 300mOsmoles/L difference=equivalent to 8 timed of atmospheric pressure
        
        atmospheric pressure=760 mliters of mercury
        calc:
        300*22.4=6720
        6720/760=8.84
        
        1 more item...
        
        shows power involved in osmosis (mov. of water) and how destructive it can be
        in terms of damage to cells
        
        regulation and presence of specialised channels and structures on the surface of memb.
        important to regulate the conc. of solutes inside and outside the cells
        
        because changes in conc. changes the osmolarity
        large changes in osmolarity= dramatic changes to the cell size and volume of cell: potentially harmful
        
        if membrane is free to move and expand
        
        the volume distribution is changed
        the osmotic forces is gonna make the v of side 2 much greater than s1>>>>>>cell is expanding
- - - - ex: normall cell v
        300 mOsmoles / L
        solution: non penetrating solutes
        Non permeable molec.
        solutes in the solutions canot cross the memb.
        so fixed osmolarity of the solution
        
        solution: 300 mOsm/L
        Isotonic solution
        
        no change in volume
        w is not going in or out of the cell
        no net movement of w
        
        An isoosmotic solution is not necessarily isotonic
        
        400 mOsm/L
        high solute conc.
        low water conc.
        hypertonic solution
        
        w diff. down its conc.
        comes out of the cell
        shrinking cell v
        
        another situation: solute is urea
        urea can diffuse across the membrane
        very low conc. of urea inside the cell:
        
        diffu. of urea down its conc. grad.
        increase the osmolarity inside the cell
        w is gonna follow that
        
        we need to consider
        
        the osmolarity of the solution that we put the cell in
        
        how permeable is the membrane to the solutes in that solu.
        if so>>>>change the osmolarity>>> change the water conc.
        change the relationship betw. cell and solu.
        
        1 more item...
        
        solution: 200 mOsm/L
        hypotonic solution
        
        w conc. is higher outside the cell
        w diffuse down its conc. grad.
        cause the cell to swell
- - - - ex further breaks down
        
        interstitial fluid=betw cells
        
        fluid in plasma
  - - - needs to be tightly regulated to maintain the volume of our cells and conc.
    - - physiological eg. of the effect that changes in hydrostatic pressure and osmosis can have in the body
        
        filtration and absorption of fluid
        across capillary
        
        driven by changes in osmolarity
        
        arterial site of the vascular sys.
        
        we have a net filtration force:
        by adding:
        have net effect of filtering the fluid out
        out of the capillaries in to the interestitial fluid
        
        hydrostatic pressure=33out
        
        oncotic pressure=colloid osmotic pressure=20 in
        
        net filtration or reabsorption pressure=13out
        
        cross the capillary from arterial site to venous site
        
        decrease in hydstatic pressure=13 out
        
        osmotic pressure not going to change=20 in
        
        adding up: net inward going force
        = re-absorption of fluid on the venous side= 7 in
        
        water gets filtered out=arterial side
        reabsobtion back in= venule site
        
        regulation of fluid within plasma
        loos alittle bit but most of it gets back
- - - - large amount of fluid being lost out of the plasma
      - building up in interstitial space
      - effects on the volume of the tissues of the body
      - for example if we increase the hydrostatic pressure
        
        increase in filtration forces
        
        exceeds the ability of the lymphatic system to drain that fluid back
        
        ends up with oedema and potential tissue damage