Page 113 - The Miracle in the Cell Membrane

Harun Yahya (Adnan Oktar)

Isotonic Hypotonic Hypertonic
(Osmotic pressures (Osmotic pressure lower (Osmotic pressure high-
being equal) than that in the cell) er than that in the cell)

Water regularly passes through the red blood cell's membrane. If too
much water enters, that could split the cell and lead to its death. If not
enough water enters, the cell will shrink and lose elasticity. Under typ-
ical conditions, the amount of water passing in both directions has so
sensitively adjusted that the cell's volume remains stable.

Water mol e cu les pass through the cell mem brane in
large quan ti ties by means of sim ple dif fu sion. The con -
stant flow through the cell mem brane is very impor tant
for the body—for exam ple, in the secre tion of and
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absorp tion of water in your small intes tine. In addi tion,
water reg u lar ly flows in both direc tions through the red
blood cell's mem brane.
The level of water flow ing in both direc tions has been
very care ful ly reg u lat ed, so that the amounts of water
enter ing and leav ing are equal. Thus the cell's vol ume
remains the same. Under some con di tions, how e ver, a
dif fer ence forms in con cen tra tion between the two sides
of the mem brane, and the cell either swells or shrinks,
depend ing on the direc tion of the water's move ment.
For exam ple, if there is a large pro tein mol e cule
inside a cell, the inward flow of water will be fast er than
the speed at which it exits, and the cell will expand. The

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