Going Beyond Muscles & Bones

Have you ever observed how the respiratory system is affected when practicing asana? Sometimes I get so involved with the skeletal muscular system that all my awareness of the respiratory system is so far in the background that I’m unaware of it. Other times I’m so involved with the respiratory system, that I lose track of the skeletal muscular system.
I find it interesting how these two systems affect one another, how when I overuse one system the other is affected. So for example, if I over use the skeletal muscular system then it has an affect of straining and then this results in holding my breath.
This brings me to something that I wondered about for a long time. I read in different yoga books and have heard teachers talk about how a particular asana has benefits for a particular body system. Now I understand how hamstrings lengthen in an asana, because I feel it. But when it came to the effects on my liver, for example, then I couldn’t feel it. But what I found out was the sensation of the liver and the sensation of the hamstrings were two different things. They express themselves in different ways.
This goes back to the skeletal muscular and respiratory systems; they both have different ways of expressing themselves. So sometimes in a practice I’ll go to Light on Yoga and look up what systems are affected in the asanas that I’m practicing that day. Then I observe as I’m practicing how these different systems are expressing themselves. This is a interesting way of practicing because it shows what systems are over used and what systems are under used.