Question

What will happen if stretch receptors of the urinary bladder wall are totally removed?

1. There will be no micturation
2. Urine will not collect in the bladder
3. Micturation will continue

Answer 1

1. There will be no micturition.

Explanation:

The stretch receptors basically function by sending signal to the brain. After receiving the signal it relaxes the bladder so that the urine passes out. In case the stretch receptors are removed or damaged, they would not be able to send the apt signal and hence would remain closed leading to no micturition.

Answer 2

There may or may not be micturition based on brain behavior. Urine will collect in the bladder.

Explanation:

If the stretch receptors are removed, then there would be no indication of amount of urine filled in the bladder.

Micturition is a voluntary activity for most people over age of 5. This is because the external sphincter muscle is a skeletal muscle, and is affected by somatic nervous system (pudendal nerve).

Urine is created through filtration at the kidneys. This process may be hastened or slowed through various pathways. It is unknown (to my knowledge) whether stretch receptors affect rate of filtration from kidneys.

Now let's use these information to generate a thought experiment. If we remove the stretch receptors, then kidney's filtration rate would not be affected by state of the urinary bladder. Thus, urine would continue to come into the bladder.

Since micturition is a voluntary activity, there needs to be a signal from the brain. If there is no way for the brain to know when the bladder is full, the brain may not give the signal to micturate.

Here's where this question becomes unanswerable. The brain behaves in very complex ways, including your behavior to ask this question and my behavior to answer this question. Similarly, the person may have a habit formed such as going to the bathroom every 5 hours. Thus, the brain may give the signal to micturate without information from stretch receptors. This is analogous to diabetes II patients of old days controlling their glucose level without knowing the actual level by following a diet schedule.

So micturition may continue, or it may not. One thing for sure is that if the person does not micturate for a long time, it could damage the surrounding organs. Maybe the pain receptors from surrounding organs will be the new stretch receptors to know when to micturate.

Sources:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2897743/
https://en.wikipedia.org/wiki/Pudendal_nerve