2. The composition of major components in intracellular fluid is listed below in

Question

2. The composition of major components in intracellular fluid is listed below in column 2. Assume that a neutrophil having this intracellular fluid composition is placed in a solution having the composition shown in column 3 a. Estimate the osmotic pressure difference across the cell membrane arising from the concentration differences listed in the table. Assume that the cell membrane is impermeable to all of the listed components, and the cell is at body temperature (37C) b. Knowing that the pressure in the cell equals the pressure outside the cells, and that an osmotic pressure creates a stress across the membrane in the same way that pressure does, compute the stress acting in the cell membrane from osmotic effects. Assume that the thickness of the membrane is 0.lum, that the cell is a perfect sphere of radius 12um, and that all transmembrane stresses are carried by the cell membrane (i.e. ignore the cytoskeleton) C. If Young's modulus for the neutrophil's membrane is 300 pN/um', compute the resulting strain in the membrane. Note that lpN-10 N d. Does this strain seem reasonable? Can you think of factors we have neglected which will change this calculation Table 4.6. For Problem 424. From Vander et af. 1101. Reproduced with kind pecmission ef The McGraw Ha Companies Extracellia fluid 15 1.5 12 10 10 ?. 1.5 110 30 Amino acids8 56 02

Explanation / Answer

Osmotic pressure =?Concentration*R*T

=>Inside Osmotic pressure = (15+150+1.5+12+10+10+40+8+1+4+4)*10^-3*.082*(37+273)=6.49 atm

=>Outside Osmotic presure = (90+4+1+1.5+110+30+2+2+5.6+0+.2)*10^-3*.082*(37+273)=6.26 atm

=> Osmotic pressure difference = 6.49-6.26=.23 atm

b) Considering cell to be elastic, then Pressure, P =2/3*stress*(1-a^3/b^3)

a, Internal diameter= 12 um

b, outside diameter = a+thickness= 12+.1=12.1 um

=>.23=2/3*stress*(2-(12/12.1)^3)

=>Stress=14 atm

c) Strain= stress/young modulus = 14*10^5/(300*10^-12/10^-12)=4666

d) Other factors which may affect are interaction between Particles which affects osmotic pressure.

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