Without reading the other posts....
Psychology aside (my favorite subj), PHYSIOLOGICALLY speaking certain (many many many) nerve pathways are necessary for bladder control.
This is going to get technical for a moment, and then I'll do a quick sum up...I never know how much is too technical:
There are actually several pathways involved, and are regulated by BOTH the central and peripheral nervous systems. The bladder and urethra are innervated by 3 sets of peripheral nerves arising from the autonomic nervous system (ANS) and somatic nervous system. The central nervous system is composed of the brain, brain stem, and the spinal cord...and having CONSCIOUS control is located in the frontal lobes, while being AWARE that there is fullness is in the brainstem...The conscious sensations associated with bladder activity are transmitted to the pons (brainstem)from the cerebral cortex (frontal lobes). The awareness involves signals being passed from the bladder and urethra up the spinal cord into the brainstem, and then into the frontal cortex.
When the bladder becomes full, the stretch receptors of the detrusor muscle (what surrounds the bladder) send a signal to the pons, which in turn notifies the brain. People perceive this signal (bladder fullness) as a sudden desire to go to the bathroom. Under normal situations, the brain sends an inhibitory signal to the pons to inhibit the bladder from contracting until a bathroom is found.
In infants, the higher center of voiding control (the brain) is not mature enough to command the bladder, which is why control of urination in infants and young children comes from signals sent from the sacral cord. (Otherwise known as NOT THE BRAIN, but a part of the spinal cord rather low in one's back). When urine fills the infant bladder, an excitatory signal is sent to the sacral cord. When this signal is received by the sacral cord, the message is sent directly to the bladder muscle to contract. The result is involuntary detrusor contractions with coordinated voiding.
The filling of the bladder depends on the intrinsic viscoelastic properties of the bladder and the inhibition of the parasympathetic nerves.
Sympathetic nerves also facilitate urine storage in the following ways:
* Sympathetic nerves inhibit the parasympathetic nerves from triggering bladder contractions.
* Sympathetic nerves directly cause relaxation and expansion of the detrusor muscle.
* Sympathetic nerves close the bladder neck by constricting the internal urethral sphincter. This sympathetic input to the lower urinary tract is constantly active during bladder filling.
All of this, in short, is:
- Babies and young children not only have NO control, their bodies are actually signaling for them to pee the same way their body is signaling for their heart to beat.
- Children frequently WANT to be potty trained long before they are physically capable. This creates a lot of frustration on their part. I mean, how would YOU feel?
- Their brain has to develop to a point where it can actually start receiving and sending these complex series of signals (walking is actually far easier to learn. Hence, why kids DO walk first).
- The entire system of nerve response has to SWITCH (not just develop, like walking). This is a BIG reason why potty training can start and stop, and comes in stages unless you wait until their entire system is wired (at about age 3). Not only do the systems have to rewire (which means that for a while they will have TWO active systems, that they can't choose between, and then that they have to remember the right one)....but if there's anything going on that's affecting physical development of the nervous system, the LEAST IMPORTANT THINGS (like, alas, not needing to spend an arm and a leg buying diapers), get put on hold while a different aspect of the nervous system starts building.
- Brain and nerve development is different for every individual.
- Adding EMOTIONS in, throws the whole system out of wack. Because, yep, you guessed it....the urge to pee is not only tied to the physical, but runs along some of the same paths (and is tied together) with the nerves related to our emotions. A few examples we've all (or most of us) have felt would be: needing to pee more when you're scared, or nervous, or excited. Or after sex. Or when taking depressants (like alcohol).
So these things take time. And as I'm sure you'll hear from all of us who've been through it..."pushing" creates stress...which creates less bladder control.
I'm not saying your child isn't ready. I've know kids who were totally potty trained by age one, and kids who weren't (daytime) potty trained until after they were 3 or 4. It has VERY little to do with parenting.
Most children start exhibiting some form of control as infants. But that's their systems starting two switch. And unfortunately, that switch typically takes at least a year from the time they first start to "hold it".
Of course, night-time control is a whole different animal.