AJP - Regulatory, Integrative and Comparative Physiology, Vol 233, Issue 3 145-R161, Copyright © 1977 by American Physiological Society
Oxygen exchange in a simulated trout gill secondary lamella
D. G. Smith and D. W. Johnson
The complex blood flow patterns occurring in a trout secondary lamella were
computed from a theoretical electrical model consisting of a
two-dimensional array of unitary resistances representing the blood
channels of the lamella. Estimates of oxygen uptake from water to blood
were made by means of the standard conductance equations for oxygen and
values from the literature for blood and water PO2's in trout. The results
were plotted as contour charts of blood and water PO2, O2 transfer, and
blood flow. According to the results of various manipulations of this
model, oxygen exchange across a given lamella will be largely unaffected by
changes in the overall shape of the lamella. However, the model predicted
that oxygen exchange would be greatly reduced if 1) the basal pillar cell
channels were denied access to the respiratory water flow, 2) pillar cell
contraction were to force blood into the larger-diameter marginal channels,
or 3) the blood flow rate were to be increased, regardless of a concomitant
increase in water flow. These predictions are discussed in terms of current
theories of gas exchange in teleost gills.
