krogh length krogh length the krogh length, λ k , is the distance between capillaries at which nutrients diffuse to based on cellular consumption of the nutrients. it can be described as: λ k = d s c o / r =c_/r}}} where d s is the diffusion constant of the solute in the substrate, c o is the concentration in the channel, and r is the consumption by the cells. units are in terms of length.