We were intrigued by the photos and blowups in John Clancy’s excellent book “The Human Body-Close Up” we browsed through the book from the back and were amazed at the detailed photos of the human body and its various parts. We were surprised when we approached the front of the book to find a blowup drawing of a cell. The detailed view was very complex. Blown up photos of body parts show rather simple structures. For a cell, many scientists have proposed a variety of models to visualize the observed behavior and molecular activity of a cell. The pictorial view of a cell shows detailed partitions within the cell. Multiple transport mechanisms are proposed for molecular movement across the cell membrane. These include voltage, ligand, and mechanically gated channels; exo- and endo- cytosis; protein channels; etc. In the early 1900’s, scientists discovered that insulin was required for glucose transport across a cell membrane. Perhaps similar hormones are involved in transport across cell membranes. Perhaps even a simpler model exists for he trillion cells in our body.
We had the opportunity to look at osmosis after presenting a simple engineering solution to a control problem. We showed that osmotic flow proceeds as molecular flow from a high vapor pressure to low vapor pressure region (high concentration to low concentration region — just the same as the diffusion) and showed that applied osmotic pressure raises the vapor pressure of the solution side of the membrane. Molecular flow rather than bulk fluid flow is the mechanism for osmotic fluid transfer. In the 1950’s Glasstone (Textbook of Physical Chemistry) noted that there “ … were three main views concerning … osmotic pressure … but it does not seem possible to decide between them.”
In the same manner, Perhaps, there is a much simpler model to explain the molecular and macro behavior of a cell.
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Larry Howlett © 2019 LDH@HTMDengineering.com