The Urinary Bladder – Anatomy, Structure & Related Conditions

The urinary bladder holds the urine and is round in shape. On average, it can hold 500-700ml of urine. After this point, when the bladder is full, the muscles in the bladder contract, and the sphincter muscle located in the urethra relaxes and lets the urine flow out of the body. 

The muscles in the bladder are responsible for the conscious control of urination. It includes two paths,

1. The sensation that instructs you that the bladder is full and has to be let out.
2. The motor control to let the urine pass out. 

Sensory signals are transmitted through the parasympathetic nervous system once the urinary bladder fills and is closer to being full. This initiates the detrusor muscle to contract. This makes the bladder pass the urine through the urethra. Additionally, through innervation by the sympathetic fibers and non-sympathetic fibers, motor control is achieved to control urinating voluntarily. 

Urine flows through two important sphincters to get out of the body. They are, voluntarily controlled external sphincter and autonomically controlled internal sphincter. For urination to take place, both of them need to be open. 

The contraction of the detrusor muscle lets out the urine. The backflow of urine into the kidneys and ureters is prevented by closing the ureteric orifices. 

Anatomy of Urinary Bladder

Bladder is placed in the lower part of the abdomen. The bladder is connected to the hip bone and other organs with bands of tissues i.e ligaments. They keep the bladder in its place. 

In men, it is placed between the pubic bone in the front and the rectum in the back.  And in women, it is placed in front of the uterus and vagina. 

The bladder can expand up to six inches when full and is normally about two inches. It is light or dark pink in colour, and it consists of three layers.

• Lamina propria (submucosa) – It is a thin layer of loose connective tissue. It comprises blood vessels, nerves and protein molecules. 
• Muscular propria – It is the muscle layer that is thick and on the outside of the bladder. The muscles that tighten and relax automatically are called the smooth muscles. 
• Urothelium – Urothelium is the inner layer of the bladder. This layer prevents the urine from leaking into your body. 

These are the four segments of the bladder:

• Body – The body of the bladder is placed between the base and the dome. 
• Base – The base, also known as the Fundus, is the part in the bottom back of the bladder.
• Dome – The top-front part that points to the abdominal wall of the bladder is called the dome. 
• Neck – The bladder neck is a narrow group of muscles that connect to the urethra. It is placed along the base of the bladder. 

Common Bladder Issues

Many issues can affect a person’s bladder. When a person is affected by these issues, it might just affect their urinary tract, or the symptoms can be seen in other parts of the body. Some of the common conditions that affect the bladder are explained below:

1. Urinary Tract Infection (UTI)

Urinary tract infection, commonly known as UTI, is the most common cause for bladder pain. When bacteria make its way through the urethra and causes infection it is called a UTI infection. Few of the symptoms of Urinary Tract Infection are pain the in the bladder, burning feeling during peeing and frequent urination. Females have a higher chance of developing UTI than the other genders. 

2. Incontinence

Incontinence is when an individual partly or completely loses the ability to control urinating. Incontinence can be caused because of several conditions, it happens due to the relaxation of the muscles around the urethra without warning. When this happens, a person leaks urine. Individuals who are female at birth are at risk of developing this condition, just like UTI.

3. Bladder pain syndrome

Bladder pain syndrome or interstitial cystitis is a chronic condition that a person might develop. Even though the symptoms of bladder pain syndrome seem to be similar to UTI, like UTI do, they do not respond to antibiotics. People assigned female at birth have a higher chance of getting affected by this condition.  

4. Bladder stones

Bladder stones are nothing but small deposits of minerals that are found inside the urinary bladder. These minerals take up the shape of small stones and hence are called bladder stones. The stones comprise at least 50% of uric acid and are also calcified. Sometimes, these stones are symptomless, but some symptoms include pain or discomfort during urinating, weak urine stream and a small amount of blood in the urine. They are majorly caused by an individual having trouble urinating.  

5. Bladder cancer

Bladder cancer is caused when the cells in the bladder grow out of control. Blood in urine is commonly noticed in individuals suffering from this condition. Pain while urinating and changes in urine frequency are also a few symptoms of bladder cancer.

Conclusion 

The urinary bladder is the place where the urine is stored before releasing it through the urethra. It is a part of the urinary tract and can hold up to two cups of urine. It is attached to the pelvic bones and other organs around.

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