Functions of the urinary bladder depend entirely on the autonomic nervous system. Available v or v -. 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. Most relapses occur within the first two years, and the relapse risk drops significantly thereafter. Lacteals absorb fats and fat-soluble vitamins to form a milky white fluid called chyle.
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. 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. The urethra is the channel that conveys the urine from the bladder to the exterior.
In the male it is about 20 centimetres long and carries not only the urine but also the semen and the secretions of the prostate, bulbourethral, and urethral glands. During urination and ejaculation it opens up, and its diameter then varies from 0. The male urethra has three distinguishable parts, the prostatic, the membranous, and the spongy, each part being named from the structures through which it passes rather than from any inherent characteristics.
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. 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. The female urethra is much shorter 3 to 4. 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. 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.
We welcome suggested improvements to any of our articles. You can make it easier for us to review and, hopefully, publish your contribution by keeping a few points in mind. Your contribution may be further edited by our staff, and its publication is subject to our final approval.
Unfortunately, our editorial approach may not be able to accommodate all contributions. Our editors will review what you've submitted, and if it meets our criteria, we'll add it to the article. Generalized lymphadenitis can happen when a disease spreads through the bloodstream and affects the whole body.
Causes range from sepsis to an upper respiratory tract infection. If the lymphatic system does not work properly, for example, if there is an obstruction, fluid may not drain effectively. As the fluid builds up, this can lead to swelling, for example in an arm or leg. The skin may feel tight and hard, and skin problems may occur.
In some cases, fluid may leak through the skin. Obstruction can result from surgery, radiation therapy , injury, a condition known as lymphatic filariasis, or—rarely—a congenital disorder. The "swollen glands," that occur, for example, in the neck during a throat infection, are in fact enlarged lymph nodes.
Reaction to an infection: The lymph nodes react when foreign material is presented to immune cells through the lymph that is drained from infected tissue. Direct infection of the lymph nodes: The nodes can become infected and inflamed as a result of certain infections that need prompt antibiotic treatment. Most people who have swollen glands with a cold or flu do not need to see a doctor.
Also known as infectious mononucleosis , or mono, this is a viral infection that can one cause longer-lasting swelling, a sore throat , and fatigue. This is more common in children than in adults. It occurs when the lymph nodes at the back of the mouth are fighting infection, usually viral, but sometimes bacterial. This bacterial infection is commonly called " strep throat.
Children are more prone to swollen lymph nodes because their immune systems are still developing their responses to infectious microbes. In October , researchers found that the brain has lymphatic vessels , allowing it to process "waste" leaked from the blood vessels. This could provide new insight into the relationship between the brain and the immune system.
In June , scientists announced that they had discovered a previously unknown lymphatic system that linked it to the central nervous system CNS and the brain. In May , researchers said that the lymphatic system may play a role in helping the heart to recover after a cardiac arrest. Article last updated by Yvette Brazier on Fri 23 February All references are available in the References tab.
The adaptive immune system. Molecular Biology of the Cell, 4th edition. Overview of the lymphatic system. Introduction to the lymphatic system. The lymphatic system in immunity and cancer. Tidy, C, , March MNT is the registered trade mark of Healthline Media. Any medical information published on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a healthcare professional.
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Register for a free account Sign up for a free Medical News Today account to customize your medical and health news experiences. Register take the tour. Reviewed by Elaine K. Fast facts about the lymphatic system The lymphatic system plays a key role in the immune system, fluid balance, and absorption of fats and fat-soluble nutrients. As lymph vessels drain fluid from body tissues, this enables foreign material to be delivered to the lymph nodes for assessment by immune system cells.
The lymph nodes swell in response to infection, due to a build-up of lymph fluid, bacteria, or other organisms and immune system cells. Lymph nodes can also become infected, in a condition known as lymphadenitis. If lymph nodes remain swollen, if they are hard and rubbery, and if there are other symptoms, you should see a doctor.
Please use one of the following formats to cite this article in your essay, paper or report: If no author information is provided, the source is cited instead. Latest news Chronic pain and the power of placebo. The placebo effect is stronger in some people than in others. Lymphedema should not be confused with edema arising from venous insufficiency , which is caused by compromise of the venous drainage rather than lymphatic drainage.
When the lymphatic impairment becomes so great that the lymph fluid exceeds the lymphatic system's ability to transport it, an abnormal amount of protein-rich fluid collects in the tissues. Left untreated, this stagnant, protein-rich fluid causes tissue channels to increase in size and number, reducing oxygen availability. This interferes with wound healing and provides a rich culture medium for bacterial growth that can result in infections: In rare cases, lymphedema can lead to a form of cancer called lymphangiosarcoma , although the mechanism of carcinogenesis is not understood.
Lymphedema-associated lymphangiosarcoma is called Stewart-Treves syndrome. The incidence of angiosarcoma is estimated to be 0. Since lymphedema is disfiguring, causing difficulties in daily living and can lead to lifestyle becoming severely limited, it may also result in psychological distress. Lymphedema may be inherited primary or caused by injury to the lymphatic vessels secondary. In many patients with cancer , this condition does not develop until months or even years after therapy has concluded.
Lymphedema may also be associated with accidents or certain diseases or problems that may inhibit the lymphatic system from functioning properly. It can also be caused by damage to the lymphatic system from infections such as cellulitis. Primary lymphedema may be inherited or arise sporadically.
Multiple syndromes are associated with primary lymphedema, including Turner syndrome , Milroy's disease , and Klippel-Trenaunay-Weber syndrome. Lymphedema may be present at birth, develop at the onset of puberty praecox , or not become apparent for many years into adulthood tarda.
In men, lower-limb primary lymphedema is most common, occurring in one or both legs. Some cases of lymphedema may be associated with other vascular abnormalities. Secondary lymphedema affects both men and women. In women, it is most prevalent in the upper limbs after breast cancer surgery, in particular after axillary lymph node dissection,  occurring in the arm on the side of the body in which the surgery is performed.
Head and neck lymphedema can be caused by surgery or radiation therapy for tongue or throat cancer. It may also occur in the lower limbs or groin after surgery for colon, ovarian or uterine cancer, in which removal of lymph nodes or radiation therapy is required. Surgery or treatment for prostate, colon and testicular cancers may result in secondary lymphedema, particularly when lymph nodes have been removed or damaged.
The onset of secondary lymphedema in patients who have had cancer surgery has also been linked to aircraft flight likely due to decreased cabin pressure or relative immobility. For cancer survivors, therefore, wearing a prescribed and properly fitted compression garment may help decrease swelling during air travel. Some cases of lower-limb lymphedema have been associated with the use of tamoxifen , due to the blood clots and deep vein thrombosis DVT that can be associated with this medication.
Resolution of the blood clots or DVT is needed before lymphedema treatment can be initiated. Congenital lymphedema is swelling that results from abnormalities in the lymphatic system that are present from birth. Swelling may be present in a single affected limb, several limbs, genitalia, or the face. It is sometimes diagnosed prenatally by a nuchal scan or post-natally by lymphoscintigraphy. One hereditary form of congenital lymphedema is called Milroy's disease and is caused by mutations in the VEGFR3 gene.
One defined genetic cause for congenital lymphedema is GATA2 deficiency. This deficiency is a grouping of several disorders caused by common defect, viz.
These autosomal dominant mutations cause a reduction, i. The GATA2 protein is a transcription factor critical for the embryonic development , maintenance, and functionality of blood-forming , lympathic-forming , and other tissue-forming stem cells. GATA2 deficiency-induced defects in the lymphatic vessels and valves underlies the development of lymphedema with is primarily located in the lower extremities but may also occur in other places such as the face or testes i.
This form of the deficiency, when coupled with sensorineural hearing loss which may also be due to faulty development of the lymphatic system, is sometimes termed the Emberger syndrome. Primary lymphedema has a quoted incidence of approximately births out of every 10, births, with a particular female preponderance to male ratio of 3.
Lymph is formed from the fluid that filters out of the blood circulation and contains proteins, cellular debris, bacteria, etc. The collection of this fluid is carried out by the initial lymph collectors that are blind-ended epithelial -lined vessels with fenestrated openings that allow fluids and particles as large as cells to enter. Once inside the lumen of the lymphatic vessels, the fluid is guided along increasingly larger vessels, first with rudimentary valves to prevent backflow, which later develop into complete valves similar to the venous valve.
Once the lymph enters the fully valved lymphatic vessels, it is pumped by a rhythmic peristaltic-like action by smooth muscle cells within the lymphatic vessel walls. This peristaltic action is the primary driving force, moving lymph within its vessel walls. The regulation of the frequency and power of contraction is regulated by the sympathetic nervous system. Lymph movement can be influenced by the pressure of nearby muscle contraction, arterial pulse pressure and the vacuum created in the chest cavity during respiration, but these passive forces contribute only a minor percentage of lymph transport.
The fluids collected are pumped into continually larger vessels and through lymph nodes, which remove debris and police the fluid for dangerous microbes. The lymph ends its journey in the thoracic duct or right lymphatic duct, which drain into the blood circulation. Accurate diagnosis and staging are fundamental to the management of lymphedema patients.
Diagnosis of lymphedema is currently based on history, physical exam, limb measurements, and imaging studies such as lymphoscintigraphy and indocyanine green lymphography. However, the ideal method for lymphedema staging to guide the most appropriate treatment is controversial because of several different proposed protocols. Assessment of the extremities first begins with a visual inspection.
Color, presence of hair, visible veins, size and any sores or ulcerations are noted. Lack of hair may indicate an arterial circulation problem. In early stages of lymphedema, elevating the limb may reduce or eliminate the swelling. Palpation of the wrist or ankle can determine the degree of swelling; assessment includes a check of the pulses.
The axillary or inguinal nodes may be enlarged due to the swelling. Enlargement of the nodes lasting more than three weeks may indicate infection or other illnesses such as sequela from breast cancer surgery requiring further medical attention. Diagnosis or early detection of lymphedema is difficult. The first signs may be subjective observations such as a feeling of heaviness in the affected extremity. These may be symptomatic of early stage of lymphedema where accumulation of lymph is mild and not detectable by changes in volume or circumference.
As lymphedema progresses, definitive diagnosis is commonly based upon an objective measurement of differences between the affected or at-risk limb at the opposite unaffected limb, e.
Bioimpedance measurement which measures the amount of fluid in a limb offers greater sensitivity than existing methods. Chronic venous stasis changes can mimic early lymphedema, but the changes in venous stasis are more often bilateral and symmetric. Lipedema can also mimic lymphedema, however lipedema characteristically spares the feet beginning abruptly at the medial malleoli ankle level.
According to the Fifth WHO Expert Committee on Filariasis   the most common method of classification of lymphedema is as follows: The same classification method can be used for both primary and secondary lymphedema The International Society of Lymphology ISL Staging System is based solely on subjective symptoms, making it prone to substantial observer bias.
Imaging modalities have been suggested as useful adjuncts to the ISL staging to clarify the diagnosis. The lymphedema expert Dr. With the assistance of medical imaging apparatus, such as MRI or CT , staging can be established by the physician, and therapeutic or medical interventions may be applied:.