school questions

Hi all,
I am back with some shooters which is actually school age questions though :)
When I was eating my brunch now (everybody does that nothing unusual), I tried to map the food eating actions and it sort of puzzled me..

there are lot of complicated actions brain does within no time, I agree and this research by itself is voluminous but when I swallowed the food I realize the food in the food pipe descends with very great speed which is least controlled by the voluntary action control system of brain (general terms), I tried to slow down but I couldn't, I was wondering  why

1. may be the descending velocity gained by the food is enhanced by the gravitational pull to a certain extent?
2. may be the role of gravity is not there at all? (possible?)
3. if yes how is the respiratory system works with ease releasing the CO2 outside (comparing with respect to the gravity only )
4. how does heart pumps blood higher to its level of location and against the gravity?
5. why is that we do not feel the difficulty in these against gravity mechanisms inside our body.

I am trying to think everything in terms of basic physics and mechanics.

If these are understood we have a huge application in terms of aerodynamics and space science etc and what not.

part 2

the voluntary actions just as walking, learning etc are intensely studied I do not know how far the involuntary actions such as digestion, respiration, reproduction, circulation is done from neuroscience point of view .. Can some one light me in this?