I've read about how our sub-conscious mind regulates our body's functions, often without us being aware of it. An obvious example is that we are able to keep breathing when we are asleep (does this then mean that animals also have sub-conscious minds because they too are able to breathe while asleep?).
I've noticed that I tend to start feeling the urgent call of nature when I am within a few minutes of reaching home. This has happened too often for it to be a coincidence. Surely it is the sub-conscious mind telling my body, "Now you have access to a clean, familiar and safe place for relief. Go for it." Likewise, I've also noticed that when I am out somewhere, I can go without feeling the need much longer than usual (that is, when I am home or at the office and a toilet is easily accessible). Again it must be the sub-conscious mind restraining my body: "Hold it, pal. A clean loo is not easy to come by."
So it appears that not only does the subcious mind regulate our body's functions based on our physiological needs, it also does so by assessing the circumstances on our behalf without our conscious knowledge of it.