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The Genitourinary System / The Bladder
What is it? The urinary bladder is a hollow muscular organ forming the main urinary reservoir. It rests on the front part of the pelvic floor (see below), behind the symphysis pubis and below the peritoneum. (The symphysis pubis is the joint in the hip bones in the front midline of the body.) The shape and size of the bladder vary according to the amount of urine that the organ contains. When empty it is tetrahedral and lies within the pelvis; when distended it becomes ovoid and expands into the lower abdomen. It has a body, with a fundus, or base; a neck; an apex; and a superior (upper) and two inferolateral (below and to the side) surfaces, although these features are not clearly evident except when the bladder is empty or only slightly distended.
The neck of the bladder is the area immediately surrounding the urethral opening; it is the lowest and most fixed part of the organ. In the male it is firmly attached to the base of the prostate, a gland that encircles the urethra. The superior (top) surface of the bladder is triangular and is covered with peritoneum. The bladder is supported on the levator ani muscles, which constitute the major part of the floor of the pelvic cavity. The bladder is covered, and to a certain extent supported, by the visceral layer of the pelvic fascia. This fascial layer is a sheet of connective tissue that sheaths the organs, blood vessels, and nerves of the pelvic cavity. The fascia forms, in front and to the side, ligaments, called pubovesical ligaments, that act as a kind of hammock under the inferolateral surfaces and neck of the bladder. Blood and nerve supplies The blood supply of the bladder is derived from the superior, middle, and inferior vesical (bladder) arteries. The superior vesical artery supplies the dome of the bladder, and one of its branches (in males) gives off the artery to the ductus deferens, a part of the passageway for sperm. The middle vesical artery supplies the base of the bladder. The inferior vesical artery supplies the inferolateral surfaces of the bladder and assists in supplying the base of the bladder, the lower end of the ureter, and other adjacent structures. The nerves to the urinary bladder belong to the sympathetic and the parasympathetic divisions of the autonomic nervous system. The sympathetic nerve fibres come from the hypogastric plexus of nerves that lie in front of the fifth lumbar vertebra. Sympathetic nerves carry to the central nervous system the sensations associated with distention of the bladder and are believed to be involved in relaxation of the muscular layer of the vesical wall and with contraction of sphincter mechanism that closes the opening into the urethra. The parasympathetic nerves travel to the bladder with pelvic splanchnic nerves from the second through fifth sacral spinal segment. Parasympathetic nerves are concerned with contraction of the muscular walls of the bladder and with relaxation of its sphincter. Consequently they are actively involved in urination and are sometimes referred to as the emptying, or detrusor, nerves. Structure of the bladder wall The bladder wall has a serous coat over its upper surface. This covering is a continuation of the peritoneum that lines the abdominal cavity; it is called serous because it exudes a slight amount of lubricating fluid called serum. The other layers of the bladder wall are the fascial, muscular, submucous, and mucous coats. The fascial coat is a layer of connective tissue, such as that which covers muscles. The muscular coat consists of coarse fascicles, or bundles, of smooth (involuntary) muscle fibres arranged in three strata, with fibres of the outer and inner layers running lengthwise, and with fibres of the intermediate layer running circularly; there is considerable intermingling of fibres between the layers. The smooth muscle coat constitutes the powerful detrusor muscle, which causes the bladder to empty. The circular or intermediate muscular stratum of the vesical wall is thicker than the other layers. Its fibres, although running in a generally circular direction, do interlace. The internal muscular stratum is an indefinite layer of fibres that are mostly directed longitudinally. The submucous coat consists of loose connective tissue containing many elastic fibres. It is absent in the trigone, a triangular area whose angles are at the two openings for the ureters and the single internal urethral opening. Slim bands of muscle run between each ureteric opening and the internal urethral orifice; these are thought to maintain the oblique direction of the ureters during contraction of the bladder. Another bundle of muscle fibres connects the two ureteric openings and produces a slightly downwardly curved fold of mucous membrane between the openings. The mucous coat, the innermost lining of the bladder, is an elastic layer impervious to urine. Over the trigone it firmly adheres to the muscular coat and is always smooth and pink whether the bladder is contracted or distended. Elsewhere, if the bladder is contracted, the mucous coat has multiple folds and a red, velvety appearance. When the bladder is distended, the folds are obliterated, but the difference in colour between the paler trigonal area and the other areas of the mucous membrane persists. The mucous membrane lining the bladder is continuous with that lining the ureters and the urethra. General description The urethra is a tube that conveys urine from the urinary bladder to the outside of the body. Its wall is lined with mucous membranes and contains a relatively thick layer of smooth muscle tissue. It also contains numerous mucous glands, called "urethral glands," that secrete mucus into the urethral canal. In females the urethra is about 4 cm long. It passes forward from the bladder, descends below the symphysis pubis, and empties into the labia minor. Its opening is located above the vaginal opening and about 2.5 cm below the clitoris. In males, the urethra, which functions both as a urinary canal and a passageway for cells and secretions from various reproductive organs, can be divided into three sections: the prostatic urethra, the membranous urethra, and the penile urethra. The prostatic section of the male urethra commences at the internal urethral orifice and descends almost vertically through the prostate, from the base of the gland to the apex, describing a slight curve with its concavity forward. It is about 2.5 to three centimetres long and is spindle-shaped; its middle portion is the widest and most dilatable part of the urethra. The membranous part of the male urethra is in the area between the two layers of a membrane called the urogenital diaphragm. The urethra is narrower in this area than at any other point except at its external opening and is encircled by a muscle, the sphincter urethrae. The two small bulbourethral glands are on either side of it. The membranous urethra is not firmly attached to the layers of the urogenital diaphragm. The spongy part of the male urethra is that part of the urethra that traverses the penis. It passes through the corpus spongiosum of the penis. The ducts of the bulbourethral glands enter the spongy urethra about 2.5 centimetres below the lower layer of the urogenital membrane; except near its outer end, many mucous glands also open into it. The female urethra is much shorter (three to 4.5 centimetres) and more distensible than the corresponding channel in males and carries only urine and the secretions of mucous glands. It begins at the internal opening of the urethra into the bladder and curves gently downward and forward through the urogenital diaphragm, where it is surrounded, as in the male, by the sphincter urethrae. It lies behind and below the symphysis pubis. Except for its uppermost part, the urethra is embedded in the anterior wall of the vagina. The external urethral orifice is immediately in front of the vaginal opening, about 2.5 centimetres behind the clitoris, and between the labia minora, the inner folds at the outer opening of the vagina. The urethra of the male is a tube of mucous membrane supported on a submucous layer and an incomplete muscular coat. The membrane forms longitudinal folds when the tube is empty; these folds are more prominent in the membranous and spongy parts. There are many glands in the mucous membrane, and they are more common in the posterior wall of the spongy part. The submucous layer is composed of fibroelastic connective tissue containing numerous small blood vessels, including more venules than arterioles. The thin muscular coat consists of smooth (involuntary) and striated (voluntary) muscle fibres. The smooth muscular layer, longitudinally disposed, is continuous above with the detrusor muscle of the bladder and extends distally as far as the membranous urethra, where it is replaced and partly surrounded by striated muscle of the external sphincter. The somatic nerves to the external sphincter are the efferent and afferent components of the pudendal nerve, arising from the second, third, and fourth sacral segments of the spinal cord. The female urethra has mucous, submucous, and muscular coats. As in the male, the lining of the empty channel is raised into longitudinal folds. It also shows mucous glands, mentioned in the preceding paragraphs as existing in the male urethra. The submucous coat resembles that in the male, except that the venules are even more prominent. In both sexes, but especially in females, this layer appears to be a variety of erectile tissue. The muscular coat extends along the entire length of the female urethra and is continuous above with the musculature of the bladder. It consists of inner longitudinal and outer circular layers, and fibres from the latter intermix with those in the anterior wall of the vagina, in which the urethra is embedded. Bladder Functions Urine collection and emission Bladder function in micturition Certain reflexes combine to ensure both maintenance of a steady holding state for urine and normal progressive micturition (the desire to urinate) with complete emptying. When the internal pressure of the bladder rises, it contracts; and it also contracts when urine enters the urethra. Micturition is defined as the desire to urinate, and is a complex activity, partly reflex and unconscious and mediated by the lower spinal cord centers, and partly under conscious control by the higher centers of the brain. Voluntary micturition begins with willed messages from the brain that reach the bladder via the motor fibres of the pelvic nerves to stimulate the detrusor, at the same time actively relaxing both urethral sphincters. But the reflexes already mentioned ensure that, once the process has begun and urine has entered the urethra, the contraction of the detrusor will continue and the sphincters will remain relaxed until evacuation is complete and the bladder empty. Evacuation is aided by voluntary contraction of a wide range of accessory muscles. The muscles of the abdominal wall contract to increase pressure on the bladder from without; the diaphragm descends and the breath is held; at the same time there is relaxation of the muscles of the perineal floor. Thus voluntary initiation and control of micturition is effected partly by an active process of stimulating parasympathetic sacral nerve outflow, partly by removing the normal inhibition exerted by the higher centers on the reflex centers in the spinal cord. Once begun, micturition is carried through to completion by lower and higher centers acting in concert; sensory messages from the urine-distended urethra also play a part. It follows that even if a bladder is not particularly distended and if reflex emptying is not urgent, the bladder can nevertheless be evacuated by voluntary contraction of the abdominal wall, so initiating the reflex process that, once begun, takes over. Symptoms of Bladder Dysfunction 1) The symptoms of bladder malfunction are most often quite obvious and include burning and/or frequent urination, the urgency to urinate but yet not have much volume. cloudy urine with pus and/or blood, and low back or abdominal pain. Typically, if a person feels more pain at the beginning of urination, the infection in lower in the urinary tract, i.e., the bladder. If pain or burring on urination occurs late in the cycle, the infection can be higher up in the urinary tract, i.e., the kidneys. Prevention and Treatment of Bladder Dysfunction Foods and beverages do not usually cause bladder symptoms to develop; however, some items can make symptoms worse, potentially exacerbating feelings of urgency, urinary frequency, and even wetting accidents. 1) Decrease or eliminate alcohol, caffeinated drinks, such as coffee, tea, and cola. (These products contain methylxanthines, or diuretics, which can make you urinate). Artificial sweeteners or sugar substitutes such as NutraSweet®* may increase symptoms as well. 2) Spicy and acidic foods may affect your bladder and cause irritation. Carbonated beverages, citrus juices and fruits, tomatoes and tomato-based products, and chocolate may also contribute to this problem. 3) Many people who experience bladder control problems substantially decrease the amount of fluid they drink. Excessive fluid intake can certainly cause one to urinate more frequently. However, decreasing fluid intake too much can also have a negative impact on overall health. Although drinking less might decrease the amount of urine your kidneys produce, it can also cause urine to become highly concentrated (dark yellow and strong smelling). This can be irritating to the bladder, causing frequent urination even when the amount of urine in the bladder is low. It is also important to spread your intake of fluids throughout the day; drinking a large amount of fluid at one time often leads to sensations of urgency. 4) Constipation can place added pressure on the bladder, causing a negative effect on the way your bladder functions. By eating a healthy diet, however, you may be able to avoid constipation and lessen bladder symptoms. To help maintain bowel regularity, be sure to keep your diet high in fiber by including foods such as beans, pasta, oatmeal, bran cereal, and whole wheat bread. Also, stay physically active by exercising regularly. Finally, decreasing fluid intake too much may contribute to constipation. 5) In addition to eating the right types of food, it is important to eat the right amounts of food. Overeating can lead to weight gain, which can put unnecessary pressure on your bladder; this may trigger urine leakage when you laugh or cough. Maintaining a proper weight is certainly beneficial to your overall health. 6) See a good chiropractor to check for problems especially in the lower back region. 7) Avoid antibiotics for bladder infections if at all possible. Consider using natural alternatives such as Thymex®, Cataplex® A-C, Phosfood® Liquid, Biost ®, Min-Chex ®, Ribonucleic Acid, and Congaplex ®. 8) If urinary incontinence is a problem, do the Kegal exercises. Contact Reflex Analysis Findings The following reflexes may be active when the bladder is in a state of dysfunction:
These reflexes should be tested and treated with the proper supplementation. Get Additional Help Free Health Tests & Professional Consultations Take this preliminary
Free Test to see if your condition could respond to treatment. Use our NutritionLocator to find a doctor in your area.
Do you have urinary incontinence? Find more information here. Additional information regarding conditions of the urinary tract can be found here.
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