What is the purpose of the urinary bladder?

The bladder is what collects the urine from your body, prior to urinisation, or disposal, of the liquid. Think of it like a storage tank. If you didnt have a bladder, you would have nowhere to store the urine in your body, and youd end up either falling very very sick, or running to the loo every 2 minutes to pee 2 drops of urine.