The Bladder and How it Works

Most folks are acquainted with the sensation of a full bladder along with the urge to go to the bathroom but exactly what is the bladder and just how does it become full in the first place.

What Do Kidneys Do

Two small internal organs known as the kidneys, which are part of the body’s renal system, fill the bladder. They perform several vital functions such as filtering the blood, assisting in the regulation of electrolyte levels in the body, and controlling the amount of fluid in the body. They accomplish this by excreting excess fluid through the ureters down into the bladder.

Even though the kidneys filter around forty-two gallons or one hundred and sixty liters of blood each day, they only produce a couple of liters of urine per day. Approximately 5% of that fluid is dissolved material like urea, small quantities of protein along with other substances. The remaining 95% is ordinary water.

Diagram of a normal urinary tract showing the kidneys, ureters, bladder, and urethra

Diagram of a normal urinary tract – Image NIDDK NIH

How Much Fluid Does the Bladder Hold

While the kidney shaped kidneys are full of small filtering sacs known as neprhons, the bladder itself is hollow and much more balloon shaped. It is located within the pelvic area immediately to the rear of the pubic symphysis or pubic bone and stores the urine the kidneys expel.

As it swells with fluid, the bladder becomes rounder. At its maximum, the typical adult bladder holds around two cups or half a liter, although the urge to urinate usually starts at around one cup.

Human Urinary System animation video 3d | Formation of urine

What Does the Bladder Do

Once the physical volume of the bladder increases, it pushes on nearby nerves, called stretch receptors. As soon as that begins to occur, those nerves transmit signals to the brain that tell us to urinate. Of course, for the majority of folks, that does not occur instantly since the bladder is among the handful of internal organs that we have a significant amount of conscious control.

Counter-acting the urge produced by those nerve signals, we are able, up to a point, to utilize the urethral sphincter muscles to hold back. For many folks, that hold back period can be as long as five hours.

After that, whether through losing control or perhaps through an act of will, we contract the bladder muscles in order to push urine through a tube known as the urethra. However, we must do more than just push given that we also have to relax those ring like sphincter muscles to permit the urine to flow. It is a consequence of inadequate control of the latter, which leads to urinary incontinence.

The urethra, along with the ureters and the bladder itself, are lined with a type of mucous, which stops fluid movement through their material. The bladder muscles have the ability to function as they do due to their three layers, known as the mucosa, submucosa, and detrusor. The center layer is made up of blood vessels, which feed the cells of the organ. The outer layer on the other hand does the hard work when it comes to urination. Whenever you press down in order to urinate, you are contracting this muscle.

That feeling of relief after emptying the bladder is the result of those same nerves now signaling to the brain, that the job is done.