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The bladder is a triangle-shaped, hollow organ in the lower abdomen that stores urine until it leaves the body. It is part of the urinary system, which also includes the kidneys, renal pelvis, ureters, and urethra. The bladder is made up of several layers, including the urothelium (the inner lining), the lamina propria (a thin layer of connective tissue), and the muscularis propria (a thick layer of muscle on the outside of the bladder). The bladder's muscles play a key role in storing and releasing urine. The detrusor muscle, a collection of smooth muscle fibres, allows the bladder to contract during urination and relax to hold urine. The bladder also contains sphincter muscles that help prevent urine leakage.
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What You'll Learn
- The bladder is made up of detrusor muscle, which contracts during urination
- The bladder neck is a narrow group of muscles that connect to the urethra
- The bladder is surrounded by muscles of the pelvic diaphragm
- The bladder is a hollow, stretchy organ that holds urine
- The bladder wall contains specialised smooth muscle, which allows the bladder to stretch
The bladder is made up of detrusor muscle, which contracts during urination
The bladder is a hollow, stretchy organ in the lower abdomen that stores urine until it leaves the body. The bladder wall is made up of smooth muscle fibres, collectively known as the detrusor muscle. The detrusor muscle is responsible for the bladder's ability to stretch in response to the presence of urine.
The detrusor muscle is under autonomic control. The parasympathetic nervous system stimulates the muscarinic stretch receptors in the bladder through the pelvic nerve fibres. When urine fills the bladder, the M3 receptors located within the bladder become stretched and stimulated, leading to the contraction of the detrusor muscle for urination. The parasympathetic fibres also inhibit the internal urethral sphincter, causing relaxation and allowing for bladder emptying.
The detrusor muscle contracts during urination to push urine out of the bladder and into the urethra. The combination of detrusor contraction and urethral sphincter relaxation leads to urination. The detrusor muscle is composed of smooth muscle fibres that are longitudinal and circular. The layers of the detrusor muscle start longitudinally in the inner layer, become circular in the middle layer, and then longitudinal again in the outer layer.
The bladder receives input from both the autonomic (sympathetic and parasympathetic) and somatic arms of the nervous system. The sympathetic response causes relaxation of the detrusor muscle, promoting urine retention. The parasympathetic response, on the other hand, stimulates the contraction of the detrusor muscle, initiating urination. The somatic arm provides voluntary control over urination through the external urethral sphincter.
The detrusor muscle plays a crucial role in bladder function, and abnormalities or pathologies in this muscle can lead to urinary retention, incontinence, or deterioration of the upper urinary tracts if left untreated.
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The bladder neck is a narrow group of muscles that connect to the urethra
The urinary bladder is a hollow, stretchy organ in the lower abdomen that stores urine until it leaves the body. The bladder is part of the urinary system, which includes the kidneys, renal pelvis, ureters, bladder, and urethra. The kidneys filter the blood and create urine, which is then transported to the bladder via the ureters. The bladder can hold 500-700 mL (about two cups) of urine for two to five hours. When it's time to urinate, the muscles in the bladder contract, and the sphincter muscles in the urethra relax, allowing urine to flow out of the body.
The bladder neck is a narrow group of muscles located along the base of the bladder. It connects to the urethra, which is a tube that allows urine to pass outside the body. The bladder neck is also known as the preprostatic urethra and is considered a distinct part of the urethra. The urethra can be divided into anterior and posterior segments, with the anterior urethra being about 15 cm long and the posterior urethra about 4 cm long.
The bladder neck plays a crucial role in bladder function, particularly in males. In males, the external sphincteric mechanism is more complex due to its correlation with the fibres of the rectourethralis muscle and the levator ani muscle. Obstruction at the level of the bladder neck or below can lead to acute retention, a medical emergency. The most common cause of obstruction in males is prostate enlargement (BPH).
The bladder itself is composed of several layers, including the urothelium, lamina propria (submucosa), and muscularis propria. The muscularis propria is the thick muscle layer on the outside of the bladder, consisting of three layers of smooth muscle. These smooth muscles are responsible for the contraction and relaxation of the bladder during urination.
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The bladder is surrounded by muscles of the pelvic diaphragm
The bladder is a hollow, stretchy organ in the lower abdomen that collects and stores urine before it leaves the body. It is part of the urinary system and is situated in the pelvic cavity. The pelvic floor muscles form the base of a group of muscles known as the core, which also includes abdominal muscles, back muscles, and the diaphragm. The pelvic floor muscles stretch from the pubic bone in front of the body to the tailbone (coccyx) in the back.
The pelvic floor muscles are a group of muscles and connective tissues that support important organs in the pelvis, such as the bladder, bowel (large intestine), and internal reproductive organs. They hold these organs in place while also providing the flexibility needed for bodily functions like urination, defecation, and sexual intercourse. The pelvic floor muscles also help protect the spine and organs by absorbing outside pressure from activities such as lifting or coughing.
The pelvic diaphragm, also known as the pelvic floor, is a wide but thin muscular layer of tissue that forms the inferior border of the abdominopelvic cavity. It is composed of a broad, funnel-shaped sling of fascia and muscle, extending from the symphysis pubis to the coccyx and from one lateral sidewall to the other. The pelvic diaphragm includes muscles such as the levator ani, which is composed of three separate paired muscles: pubococcygeus, puborectalis, and iliococcygeus. The pubococcygeus forms the bulk of the levator ani complex and provides stability and support for abdominal and pelvic organs.
The bladder itself also has muscle layers, with smooth muscle fibres collectively known as the detrusor muscle forming its walls. The detrusor muscle contracts during urination to push urine out of the bladder and into the urethra, and it relaxes to allow the storage of urine. The bladder neck, along the base of the bladder, is a narrow group of muscles that connect to the urethra. The external urethral sphincter is under voluntary control and is the same in both sexes, although in males, it correlates with fibres of the rectourethralis and levator ani muscles.
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The bladder is a hollow, stretchy organ that holds urine
The bladder is made up of several layers, including the urothelium, lamina propria, and muscularis propria. The muscularis propria is the thick muscle layer on the outside of the bladder, consisting of three layers of smooth muscle. The detrusor muscle, which is also made up of smooth muscle fibres, is located within the bladder walls. This muscle is responsible for the contraction of the bladder during urination and its relaxation when storing urine. The detrusor muscle is controlled by the autonomic system and receives signals from both the sympathetic and parasympathetic nervous systems.
The bladder's capacity varies depending on the amount of urine it contains and the pressure exerted by surrounding organs. A healthy adult bladder can typically store up to two cups of urine for two to five hours. The bladder can stretch to accommodate the urine, expanding from about 2 inches when empty to 6 inches when full.
The process of urination involves the coordination of the detrusor muscle and the internal and external urethral sphincters. When the bladder is full, the M3 receptors are stimulated, leading to the contraction of the detrusor muscle. Simultaneously, the parasympathetic fibres inhibit the internal urethral sphincter, causing it to relax and allowing for bladder emptying. During this process, the brain signals the bladder muscles to tighten and the sphincter muscles to relax, facilitating the release of urine.
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The bladder wall contains specialised smooth muscle, which allows the bladder to stretch
The urinary bladder is a hollow organ in the lower abdomen that stores urine until it leaves the body. The bladder is part of the urinary system, which also includes the kidneys, renal pelvis, ureters, and urethra. The kidneys filter blood and create urine as a waste product, which is then carried to the bladder by the ureters. The bladder can hold up to two cups of urine for two to five hours.
The bladder wall contains specialised smooth muscle known as the detrusor muscle. This muscle is composed of fibres oriented in multiple directions, which allows the bladder to retain its structural integrity when stretched. The detrusor muscle contracts during urination to push urine out of the bladder and into the urethra. At the same time, the brain signals the sphincter muscles to relax, allowing urine to exit the bladder. When the bladder is filling with urine, the detrusor muscle relaxes to allow for the storage of urine.
The detrusor muscle is controlled by the autonomic system and receives innervation from both the sympathetic and parasympathetic nervous systems. When the bladder is full, the parasympathetic nervous system stimulates stretch receptors in the bladder, leading to the contraction of the detrusor muscle. At the same time, the parasympathetic fibres inhibit the internal urethral sphincter, causing it to relax and allow for bladder emptying. When the bladder is empty, the sympathetic nervous system is stimulated, causing the detrusor muscle to relax and the internal urethral sphincter to constrict.
The bladder is made up of several layers, including the urothelium (the inner lining), the lamina propria (a thin layer of connective tissue), and the muscularis propria (the thick muscle layer on the outside of the bladder). The detrusor muscle is located within the muscularis propria layer.
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Frequently asked questions
No, the bladder is not all muscle. It is a hollow organ that is part of the urinary system and is situated in the pelvic cavity. It collects and stores urine until it leaves the body. The bladder has three main layers: the urothelium, lamina propria (submucosa), and the muscularis propria.
The bladder's function is to collect and store urine. It is connected to the kidneys by two ureters, which are narrow tubes that carry urine from the kidneys to the bladder. The bladder then releases the urine through the urethra.
The bladder has three main layers. The inner layer, or urothelium, is a mucous membrane that prevents urine from leaking into the body. The second layer, or lamina propria, is a thin layer of loose connective tissue. The outermost layer, or muscularis propria, is a thick layer of smooth muscle that contracts and relaxes to expel and store urine, respectively.
The detrusor muscle is a smooth muscle located within the walls of the bladder. It contracts during urination to push urine out of the bladder and relaxes to allow the storage of urine. The detrusor muscle is controlled by the autonomic nervous system and receives signals from both the sympathetic and parasympathetic nervous systems.
Common bladder conditions include urinary incontinence, where individuals cannot control their bladder, and bladder stones, which are clumps of minerals that form in the bladder. Bladder cancer is also a condition that can affect the bladder, causing uncontrolled cell growth.
