[Middle English, from Late Latin, from Latin, standard]
a : an authoritative list of books accepted as Holy Scripture
b : the authentic works of a writer
c : a sanctioned or accepted group or body of related works
6th President of the American Physiological Society; highest award of the APS named to honor 40 years of service to the group
This year’s lecture features the career of James M. Anderson, MD, PhD, currently Director of the NIH Division of Program Coordination, Planning, and Strategic Initiatives (DPCPSI). Dr. Anderson’s research career focused on Internal Medicine and Hepatology, especially the role of tight junctions and paracellular mechanisms in epithelial transport.
What is an Epithelium?
Epithelium is a layer of epithelial cells, those that line hollow organs in the body (blue in the diagram below). This layer separates two compartments of an organ, often a space (AKA lumen) and the organ itself (the space between cells known as the interstitium). This layer provides a barrier to keep things from crossing from the lumen to the interstitium and vice versa. Transporters within the cells control what gets put into and removed from the lumen. A variety of molecules can assist movement of substances through the cells, both by using the energy made within the cells (active transport) and by providing an opening or pore of sorts to allow something to move.
An epithelium may produce other barriers to the flow of substances through it. The cells may produce a basement membrane (orange in diagram above) that helps control the movement of molecules.
If an epithelium is a sheet of cells, are there spaces between the cells? Yes…and no. Most epithelial cells have junctions between them (red in the diagram) that may block movement of some, but not all, molecules. The spaces between the cells are virtually nonexistent, yet sometimes substances can pass through this paracellular pathway.
Now, I could tell you a lot about how these things work in the kidney; however, Dr. Anderson’s work has focused on the liver. I will append lecture notes below after the event, so be sure and check back. The lecture occurs at 5:30 pm in room 20A of the convention center.
As promised, here is the stuff I live-tweeted during the event. Enjoy!