Physics of diving question...

[SmithDiving]

John, first of all I don't think you need to know which compartment saturates first - almost nobody knows this. You say you would like to have an understanding of the fundamentals of dive physics and physiology - almost nobody has this understanding as it's all theortical.  What you should understand is this (some of this I know you understand,  but just so everyone can understand) - Each tissue compartment in the body (doesn't really matter if you identify 5 or 28) fills up or off gasses a specific gas (nitrogen is what we generally deal with) at a different rate, this is described as the compartment's half-time (the number of minutes required to fill or deplete the compartment by 50%).  You are correct that softer tissues (fat cells) generally in & off gas quicker, and hard tissue (cartiledge & bone) in & off gas at a slower rate.  As I understand it, a compartment's M-Value is a US Navy term referring to "Maximum Value" for a compartment.  In other words, the maximum amount of time required for a compartment to become "full" of a specific gas.  The accepted M-value for a compartment occurs after 6 half-times when a compartment is considered to be completely filled (98%+), so a 5 minute compartment would reach it's M-value at :30 (5x6).  Up until a few years ago (pre-RGBM) all "reliable" dive tables for recreation and technical diving were based on this theory - The first tissue type to reach it's M-value for a specific depth controlled the length of the dive for that depth.  The specific calculations for in-gassing and off-gassing for specific tissue types are very complicated (mostly because they are non-linear) and are something that very few people understand - or need to for that matter.  Remember, this is all theoretical and your dive table or computer are just making calculations based on a generic diver in generic conditions.