How Does the Bladder Work?

Small print time: In order to have a successful non-messy void we have to get our nervous system involved, utilize Bradley’s loop reflex, and of course, have a functional pelvic floor. 

Quick tid bit on the Nervous System…

Both our “fight or flight” system and our “rest and digest” system work together to store and then to reflex.  Pretty simple, aye. 

Who’s Bradley?

Okay using the least amount of words as possible - In our brain and along our spinal cord we have “micturition” centers.  Each center is responsible for having awareness and the ability to void, whether it is identifying we need to go, making the detrusor muscles contract, and/or making the sphincters relax.  They all work together so we can enjoy this basic function. 

Now let’s bring in the pelvic floor

Simply put when the bladder contracts the pelvic floor relaxes. The pelvic floor contracts, the bladder (detrusor muscle) relaxes.  It’s a reciprocal relationship that works very closely together.

Written by: Dr Susana Cicchetti, PT, DPT

The bladder works in a relatively simple fashion but has some small print to it.  The brain, our habits, and pelvic floor all influence our bladder’s function and the bladder can easily get manipulated.  Let’s see if I can explain it. 

Our kidneys filter a bunch of wonderful things and provides us with urine. Urine travels to the bladder via the ureters.  Whether we are eating, running, or sleeping, our kidneys are filtering non-stop and end up filtering about 15 drops per minute.  

In general our bladder can hold up to 400-600 mL of urine and it takes about 3 hours to fill the bladder up. We usually get the feeling of having to go at around a cup, 200 mL. When that feeling happens and we are perfectly positioned on the toilet, the detrusor muscle, which is a layer inside the bladder, contracts and we pee via our urethra. 

So the work is simple - the bladder expands to fill and contracts to get the urine out.