How our body controls peeing

Cochrane reviews about urine incontinence

This post discusses how our body controls peeing and how one can lose it when a stroke occurs.

How peeing is controlled?

First, let us look at the anatomy of the structures that produce and store urine. Urine is a waste product that is filtered and passed out of the kidneys to the store-room (bladder) via two tubes (ureters).

Figure 1 below shows the tubes (ureters) that transport out urine from our kidneys and the inside view of our storage facility (bladder). As you can appreciate that the storage facility’s wall is thick. It is made up of a strong muscle called “detrusor” and stretchable to accommodate about 450-500 ml of urine.

When our bladder fills up to this much of urine, we get to know it. How?

Figure 1: A cross-section of the bladder. Source: Wikimedia commons:

We will receive messages continuously until we decide to empty the bladder through a web of nerve endings that cover the whole outer layer of the bladder wall. These nerve endings relay their situation to the nearest transit center which is stationed at a place of the lower part of the spinal cord. This center again relays this message to the master control center placed at the brain and awaits a signal of approval to open the gates.

Control gates

Go through Figure 1 again; find out the two control gates. We have two gates: the inner gate (named inner urethral sphincter) and the outer gate (named outer urethral sphincter). These are situated in the tapering lower part of the storage facility (bladder). No sooner the transit center at the spinal cord receives the approval from the brain center, it sends to messages to the gates to open and the bladder wall to contract.

What happens in a stroke?

A stroke can attack the brain’s regulatory center and as a result, may lose the ability to control the transit center. Therefore, as soon as the bladder is getting filled, urine may go through the gates.

This does not happen among all those who face a stroke, but only among those whose a large part of the brain is attacked.

Therefore, we can consider that the presence of incontinence after stroke as a marker of stroke severity and the best single predictor of survival and recovery at the end of three months.

However, brain damage is not the only reason for the incontinence after stroke; it can happen due to a myriad of other factors: inability to communicate to the caregiver for assistance; delay in reaching the disposing container; delay in transferring to the commode, and some medications such as urine pill (diuretics).

Would you like to add more to this post? You can. Add your inputs into the comments section.

Author: Prasantha De Silva