We present a model to describe the physics of chemoreception in processes d
etermined by competitive ligand binding. Our model describes the competitio
n between various populations, such as ligands vs. blockers and receptors v
s, decoys, in protein activation when diffusion is rate-determining. Full s
patio-temporal solutions can be obtained numerically. The model structure i
s kept simple enough as to permit its easy generalization to describe a lar
ge subset of the manifold of possible situations occurring in nature. The p
ower and simplicity of the proposed method are exhibited through the soluti
on of several examples which are discussed in detail. (C) 1999 Elsevier Sci
ence B.V. All rights reserved.