Voluntary bodily control vs involuntary functions

When I was in grade school, I learned that there were two types of actions with respect to my body.  There were voluntary actions, like using my muscles to type, walk around, and speak.  There were also involuntary actions, like my heart rate, digestive process, and metabolism.

I was taught that some actions in my body had to be involuntary, because if they were all voluntary, I'd have to concentrate on all of these functions in my body.  A lapse in concentration could lead to my death.

This is all well and good.  However, there are certain bodily functions that are both voluntary and involuntary.  Two examples include blinking and breathing.  When we don't pay attention, our body automatically breathes and blinks.  It is normally an involuntary action.  However, we can direct our attention to these actions and voluntarily control our rate of breath or the rate at which we blink.  Thus, these sorts of actions can be at times involuntary, and at other times voluntary.

What I always wondered about was why some actions had this property of being both voluntary and involuntary, while lots of other actions do not.  I can control the rate at which I breathe, but why can't I directly control my metabolism?

There are lots of things in my body that I have no direct control over.  I have no control over lots of sensations.  For instance, if I feel pain, I can't, without medication, decide to just not feel pain.  The same goes for emotions.  If I am sad, I can't just directly turn off this sensation.  Similarly I can't just decide to fall asleep.  If I am tired, I can close my eyes and drift off to sleep.  But there are plenty of times where I close my eyes, wanting to sleep, but don't fall asleep.  I have absolutely no direct control over my digestive and metabolic processes.  I can't directly command my body to convert the food I eat directly into energy, rather than storing it as fat.  The same goes for healing processes.

This makes me wonder about the relationship between me and my body.  It seems like I have very little direct control over a lot of things that go on in my body.  Can we conclude anything from this?    What's interesting is the fact that I have any direct control at all.  Why aren't all of my actions involuntary?  Why is it that have I some direct control rather than no direct control?  It's this mix of voluntary and involuntary actions that go on in my body that leaves me scratching my head.

This is an example of a curious feature of human beings (and maybe some other mammals as well).  We are self aware creatures.  We are not completely responsive to the environment around us.  Some parts of us are totally responsive to external stimuli.  Perhaps our metabolism, heart rate, etc. are examples.  But some of our actions aren't completely dictated by external stimuli.  Why is that?

This aspect of human beings, this sort of dual, two-tiered nature, is something I find highly fascinating.  I'll be writing about this more in later posts.