According to the urinary bladder definition “The urinary bladder serves as a temporary urine storage tank”. It is found in the pelvic cavity, below the parietal peritoneum and posterior to the symphysis pubis. The size and shape of the urinary bladder change depending on how much urine it holds and how much pressure it experiences from surrounding organs. The average bladder in the human body can hold between 300 and 500 ml before feeling the need to drain it, but it can hold much more.
Urinary Bladder Anatomy
The human urinary bladder is a distensible elastic organ that rests on the pelvic floor and is hollow, muscular, and pear-shaped. It receives urine through the ureters, which are thick tubes that run from each kidney to the bladder's superior portion. The bladder's appearance varies depending on how much urine is contained. It has an oval shape when complete and is flattened by the overlying bowel when empty.
The urinary bladder diagram shows the different parts of the human bladder and their functions are explained below:
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The inner lining of the urinary bladder is a transitional epithelium mucous membrane that connects to the ureters. Rugae are various folds in the mucosa of the bladder when it is empty. As the bladder fills, the rugae and transitional epithelium allow it to expand.
The submucosa, which protects the mucous membrane, is the second layer of the walls. It is made up of elastic fibres and connective tissue.
The muscularis, which is made up of smooth muscle, is the next layer. The detrusor muscle is made up of smooth muscle fibres that are woven together in all directions. When this muscle contracts, it pushes urine out of the bladder.
The parietal peritoneum is the bladder wall's outer layer on the superior surface. The outer layer in all other areas is fibrous connective tissue.
Three openings in the floor of the urinary bladder create a triangular region known as the trigone. The base of the trigone is formed by two openings from the ureters.
These openings are covered by small flaps of mucosa that serve as valves, allowing urine to reach the bladder but preventing it from backing up into the ureters.
The opening into the urethra is the third opening, located at the apex of the trigone. The internal urethral sphincter is formed by a band of the detrusor muscle that encircles this opening.
The Urinary Bladder's External Features Include:
Apex: The apex is superiorly positioned, pointing towards the pubic symphysis. The median umbilical ligament connects it to the umbilicus (a remnant of the urachus).
Body: Between the apex and the fundus, it is the main component of the bladder.
Fundus or Base: The fundu is situated posteriorly. It is triangular in shape, with the triangle's tip pointing backwards.
Neck: The fundus and the two inferolateral surfaces come together to form the neck. It runs parallel to the urethra.
Urine flows through the bladder from the left and right ureters and out via the urethra. The trigone, a triangular region inside the fundus, marks these orifices on the inside.
The bladder's musculature is essential for the storing and emptying of the urine.
The bladder wall includes specialised smooth muscle known as detrusor muscle that contracts during micturition. Its fibres are oriented in a variety of directions, allowing it to maintain structural integrity even when stretched.
Both the sympathetic and parasympathetic nervous systems supply it with information.
To compensate for the increased workload of bladder emptying, the fibres of the detrusor muscle also become hypertrophic. This is very common in obstructive urinary disorders like benign prostatic hyperplasia.
In the urethra, there are also two muscular sphincters or orifices:
The male consists of circular smooth fibres that are regulated by the autonomic nervous system. During ejaculation, it is thought to avoid seminal regurgitation.
Females with no sphincteric muscle are thought to have a functional orifice. The anatomy of the bladder neck and proximal urethra form it.
Both sexes have the same external urethral orifice configuration. It is a skeletal muscle that is regulated by the user. The external sphincteric process in males, on the other hand, is more complex, as it is linked to rectourethralis and levator ani muscle fibres.
The bladder's vasculature is derived mainly from the internal iliac vessels.
The internal iliac artery's superior vesical branch provides arterial supply.
This is accompanied by the inferior vesical artery in males and the vaginal arteries in females.
The obturator and inferior gluteal arteries can also contribute small branches in both sexes.
The vesical venous plexus, which empties into the internal iliac veins, is responsible for venous drainage.
The vesical plexus in males is connected to the prostate venous plexus (plexus of Santorini), which also receives blood from the dorsal vein of the penis, at the retropubic space.
Development of Urinary Bladder
A cloaca can be found at the back end of a developing embryo. This splits into a urogenital sinus and the start of the anal canal between the fourth and seventh weeks, with the urorectal septum forming a wall between these two inpouchings.
The bladder is formed from the upper and largest part of the urogenital sinus, the urethra is formed from the middle part, and the lower part varies depending on the embryo's biological sex.
The urogenital sinus gives rise to the human urinary bladder, which is initially connected to the allantois. The bladder's upper and lower halves form separately before coming together in the middle of development. The ureters are moving from the mesonephric ducts to the trigone at this time.
The base of the bladder is located between the rectum and the pubic symphysis in males. The recto-vesical pouch separates it from the rectum and places it over the prostate.
The bladder in females is located inferior to the uterus and anterior to the vagina, resulting in a lower overall capacity than in males. The vesicouterine pouch separates it from the uterus.
And when empty, the urinary bladder is of the abdomen in infants and young children.
Association of Urinary Bladder with the Nervous System
The bladder receives feedback from both the autonomic and somatic arms of the nervous system, making neurological regulation complicated.
The sympathetic nerve relaxes the detrusor muscle, allowing urine to be retained.
Increased signals from the parasympathetic nerve induce contraction of the detrusor muscle, which stimulates micturition.
The external urethral sphincter is innervated by the somatic nerve, which provides voluntary control over micturition.
There are sensory (afferent) nerves that report to the brain in addition to the efferent nerves that supply the bladder. When the bladder becomes full, they are located in the bladder wall and signify the need to urinate.
Functions of Urinary Bladder
The feeling that our urinary bladder is full and needs to be emptied, as well as the motor control of our bladder that allows us to urinate at will, are two essential mechanisms involving your bladder.
When the bladder walls are extended when it is complete or approaching maximum size, signals are sent to the detrusor muscle through the parasympathetic nervous system, causing it to contract.
The detrusor muscle is a layer of smooth muscle fibres organised in spiral, longitudinal, and circular bundles on the bladder wall. This signal would prompt the bladder to empty its contents via the urethra.
The central nervous system (CNS) receives bladder sensations via general visceral afferent fibres (GVA). GVA fibres on the bladder's superior surface accompany the sympathetic impact nerves back to the CNS, while GVA fibres on the inferior surface follow the parasympathetic efferent fibres.
Both sympathetic and parasympathetic fibres innervate the pelvic splanchnic nerves and the inferior hypogastric plexus to allow voluntary urination.
Finally, the urine must pass through two essential sphincters in order to exit the body the autonomically regulated internal sphincter and the voluntarily controlled external sphincter.
Urinary Bladder Inflammation and Infections
Infection or inflammation of the bladder is referred to as cystitis. It is most often associated with a urinary tract infection. Since women have a shorter urethra than men, it is more common in adult women. It is normal in young boys and in older men with an enlarged prostate who experience urinary retention.
The term interstitial cystitis refers to an infection of the bladder caused by anything other than bacteria.
Other causes of blockage or narrowing, such as prostate cancer or vesicoureteric reflux, the involvement of external structures in the urinary tract, such as urinary catheters, and neurologic conditions that make passing urine difficult are also risk factors.
Infections of the bladder may cause pain above the pubic symphysis in the lower abdomen, known as suprapubic pain, particularly before and after passing urine, as well as a desire to pass urine regularly and without warning. Infections are normally caused by bacteria, the most common of which is E Coli.
A medical professional can request a urine sample if a urinary tract infection or cystitis is suspected. A dipstick may be used to check for white blood cells in the urine or the presence of nitrates, which may signify an infection.
Antibiotics are used to treat urinary tract infections and cystitis, and many of them are taken by mouth. In certain cases, serious infections can necessitate the use of intravenous antibiotics.
Causes of Involuntary Urination and Frequent Urination
Involuntary urination may be caused by problems with the urinary bladder muscles or sphincters.
Since a baby's nervous system has not fully grown, the bladder fills to a predetermined level before automatically contracting and emptying.
The nervous system matures as the child grows, which means the brain can now accept signals from the filling bladder and prevent it from emptying spontaneously until it is convenient.
Involuntary urination is caused by failures in this control system, which may occur due to a variety of factors including neurologic injury, congenital defects, strokes, multiple sclerosis, and ageing.
Frequent urination is another common problem. Excessive urine production, a limited bladder capacity, irritability, incomplete emptying, or actually consuming too many liquids, either intentionally or as a result of a disease state, may all contribute to this frequent urination.
Furthermore, since the prostate is located posterior to the bladder and enlarges in elderly men, it presses against the bladder and increases bladder sensations, males with an enlarged prostate urinate more often. When a person urinates more than eight times per day, they are said to have an overactive bladder.
What is discovered in urine may also aid in the diagnosis or assessment of a patient's wellbeing. Excess protein in the urine, for example, may indicate more severe underlying health issues such as intrinsic renal failure (nephrotic syndromes), diabetic nephropathy, or infections. Kidney stones can also be caused by an excess of cholesterol or protein in the urine. A urinary tract infection may be caused by urinary incontinence or insufficient voiding of urine.
Urinary Bladder Cancer
Bladder cancer is most often caused by cancer of the urothelium, the cells that line the bladder's surface.
Bladder cancer is more common in men than women after the age of 40. Other risk factors include smoking and dye exposure to aromatic amines and aldehydes.
Except in late disease, where cancer is present, the most common symptom in an infected individual is blood in the urine. Otherwise, a physical medical examination would be usual.
Bladder cancer is most often caused by cancer of the cells that line the ureter, known as transitional cell carcinoma, but it may also be caused by squamous cell carcinoma if the form of cells lining the urethra has changed due to chronic inflammation, such as from stones or schistosomiasis.
Preventive Measures to Keep Urinary Bladder Healthy
To prevent urinary tract infections, urinate completely.
To flush out bacteria, drink plenty of water.
To stop retaining fluids, go for a walk on a regular basis.
To help prevent bladder cancer, avoid smoking.
To avoid urinary incontinence, learn how to do kegel exercises.
Keep a food diary to keep track of what you eat.
To avoid incontinence urinating, drink less beverages at specific times.
In this article about the urinary bladder, we got to know the urinary bladder meaning, a complete description of urinary bladder anatomy with a urinary bladder diagram, functions of the urinary bladder and different symptoms associated with the urinary infections.
The urinary bladder serves as a temporary urine storage tank. It is found in the pelvic cavity, below the parietal peritoneum and posterior to the symphysis pubis. The size and shape of the urinary bladder change depending on how much urine it holds and how much pressure it experiences from surrounding organs. Urine is stored in the bladder, allowing for infrequent and regulated urination. Layers of muscle tissue line the bladder, stretching to accommodate urine. The bladder's natural capacity is 400-600 ml. The bladder muscles contract and two sphincters (valves) open to allow urine to flow out during urination.