The Effect of Various Physiological Factors
Of all the physical variables concerning which we have information or for which we have means of measurement, it is the viscosity of the protoplasm more than anything else which shows changes in relation to the life and death of the cell. At any rate this seems to be true in so far as our present knowledge goes. There is but little evidence concerning changes in refractive index, birefringence, density or zeta potential of the cell as vital processes go on in the protoplasm. It is true that the (thermodynamic) potential difference between the inside and outside of a cell may change when a cell or a part of a cell shows increased activity or is injured, and it is also true that there may also be changes in the osmotic properties of the outer membrane; but even these changes, interesting and important as they are, do not show as close a correlation with vital activity as do the changes in protoplasmic viscosity. Such changes in viscosity occur when a cell grows and ages, when it goes through the process of cell division, when it is injured or dies; they seem to occur when a muscle contracts or when a nerve fiber is aroused, or when, for one reason or another the activity of a cell or its ability to respond is inhibited or suppressed.
KeywordsZeta Potential Muscle Contract Centrifuge Method Broad Generalization Osmotic Property
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