Is there a mucous membrane in the eye?
There is no mucous membrane in the eye. What is colloquially perhaps called the mucosa is the conjunctiva. It connects the inside of the eyelids with the eyeball and is kept moist by the lacrimal apparatus.
Mucosa of the urethra
The mucous membrane of the urethra is raised in longitudinal folds. From top to bottom it shows three different cell types.The uppermost one is called urothelium, a cell layer that is only found in organs of the urinary tract. The middle layer is multi-rowed and has a highly prismatic shape.
The lowest layer is multi-layered and non-cornified (also found in parts of the oral mucosa, for example). Beneath the mucosa are fine muscle cells, which are responsible for continence in the area of the pelvic floor and for the movement of urine in the rest of the urethra. There are no defense cells or glands in this mucosa.
Diseases of the mucous membrane
The mucous membrane plays a role in the following diseases:
- Chronic inflammation of the gastric mucosa
- Cystitis
- Iron Deficiency
- Esophagitis
- Ulcerative colitis
- Crohn’s disease
- Celiac disease
- Polyps in the nose
- Aphtae in the mouth
- Bronchial asthma
- Candidosis
In principle, an inflammation can develop on any organ and skin type and is classically characterized by the following criteria: Redness, overheating, swelling, pain and loss of function. The mechanism behind this is always the same: tissue damage leads to a short-term reduction in blood flow and the blood supply is then increased by reflection. This leads to swelling and redness.
This, in turn, can slow down the blood flow and the immune cells leukocytes (white blood cells) can attach themselves to the site. They are attracted by certain substances (cytokines, interleukins) that mark the damaged tissue as such. This is followed by various repair and/or defense mechanisms to restore the function of the organ or tissue.
The best known and most relevant inflammation of the mucous membrane is that of the stomach lining, called gastritis. It can be acute or (mostly) chronic and has many different causes. The most common is type C gastritis.
C stands for chemical and means as a cause the prolonged use of certain drugs (e.g. aspirin) which destroy the basic mucous membrane protection of the stomach. Further classifications are based on A and B; A stands for autoimmunological processes and B for bacterial causes (Helicobacter pylori). Inflammation of the nasal mucosa can be caused by excessive use of decongestant nasal spray, for example.
An inflammation of the endometrium (endometritis) is almost always caused by bacteria. The most common pathogens are the known sexually transmitted diseases: Chlamydia and gonococcus (“gonorrhea“). (Other pathogens are: Anaerobes, Gardnerella vaginalis, E. coli, Enterobacteriaceae, Streptococci, Haemophilus influenzae, Mycoplasmas, Actinomyces).
Most often, these are ascending infections, i.e. diseases of the cervix (cervicitis), but more rarely diseases descending from the abdominal cavity (such as appendicitis, peritonitis and chronic inflammatory bowel disease). Risk factors for the development of endometrial inflammation are frequent sexual intercourse with changing partners, genital diseases (vaginosis or cervicitis) that are either untreated or of low symptoms, and foreign body implantation (intrauterine device). At the beginning of menstruation and after birth, the protective mucus plug in the cervix is lost and therefore also provides an access route for infections.
After gynaecological or surgical interventions and after previous pelvic inflammations, there is also an increased risk of developing endometritis. The symptoms can vary from mild to life-threatening. The dominant and alarming symptoms here are painful pressure, fever and a so-called purulent, creamy discharge.
The inflammation of the urethra proceeds similarly, as this is often a transmissible venereal disease. The most important pathogens are Chlamydia trachomatis and mycoplasma. The complaints are again very variable and can be burning, vaginal discharge or creamy purulent penile discharge in the morning (so-called Bonjour drops).
As with endometritis, the germ should be identified diagnostically in order to initiate antibiotic therapy. Bacterial inflammation of the oral mucosa is very rare and is more likely to occur in immunocompromised patients, i.e. patients with a weakened immune response. More frequent after antibiotic therapy is a fungal infection (oral thrush; candidosis).
Chronic inflammatory diseases such as Crohn’s disease or venereal diseases such as syphilis can also affect the mouth, but are not among the classic types of infection or leading symptoms.An erythema describes a sharply defined redness of the skin. It can be found more often on normal skin than on the mucous membrane. The erythema exsudativum multiforme is an affection of the mucous membrane.
This is a self-limiting inflammatory reaction that occurs mainly after a viral infection. Self-limiting means that it heals on its own. It appears mainly on the arms and legs, is disc-shaped, burning and itchy.
If it is particularly pronounced, the mucous membranes are also affected. A reddening of the mucous membranes in the general sense occurs in many venereal diseases that are accompanied by inflammation. Infection by the fungus Candida albicans can also be described as erythematous (erythema-like).
Depending on the function of the individual mucosa, it is subject to a more or less strong proliferation. It is a so-called unstable alternating tissue. Changes in its shape are therefore usually desired by the body.
The term “proliferation” can refer to different growth patterns of cells. Hypertrophy describes the increase in size of a tissue by enlarging the individual cells. This can concern, for example, the hormonally induced enlargement of the uterus.
Hyperplasia describes a condition in which the number of cells increases and a tissue becomes larger as a result. This concerns the hormonal cyclical build-up and breakdown of the uterine lining, i.e. it is healthy and desired (physiological). Its pathological counterpart (pathological) is called malignoma, i.e. a malignant growth.
The term tumor should be distinguished from this. In medical jargon, a tumor describes both a swelling in the context of an inflammation or an edema, and a benign or malignant tumor (benign or malignant). Proliferations can occur idiopathically (by chance), i.e. without any obvious and disease-relevant reason.
More often, however, they are caused by hormonal factors or a disturbed cell division. In every organ, cell division is limited by intracellular “rules” and barriers (present within the cell). These mechanisms can be disturbed by long-term tissue damage.
This explains, for example, why years of gastritis (inflammation of the stomach lining) is a risk factor for the development of a malignant ulcer (carcinogenesis). Sometimes the proliferation of mucous membrane organs also originates from the glands located in the mucous membrane. These are the so-called adenomas, mostly benign tumors.
Proliferations or swellings due to inflammation are more frequent and usually volatile. For example, a special form of gastritis can cause swelling of the mucous membrane folds. This disease is therefore also called giant wrinkle gastritis (Morbus Ménétrier) and is treated in the same way as a conventional one.
A cyst is an encapsulated, fluid-filled cavity that can in principle develop in any tissue. They can be congenital or develop over the course of a lifetime. Congenital cysts are the result of tissue malformation (for example the dermoid cyst).
The other form of cysts, also called acquired cysts, is caused by the prevented outflow of secretion. Since mucous membranes are connected to secretion-forming glands, cysts can develop here under certain circumstances. A distinction is made between true cysts (these have their own cell layer as a lining) and false cysts (for example, after softening of the tissue due to parasite infestation or other inflammation).
If a cyst is demonstrably filled with pus and clearly chambered, it is called an abscess. The location and process of cyst formation always play a role in the evaluation of a cyst. Cysts in the oral cavity, for example, tend to grow progressively, which can then constrict or destroy surrounding structures.
A cyst in the bone can dramatically lead to fractures, whereas a mucosal cyst is in principle less common, since it develops from soft tissue and often becomes symptomatic, i.e. causes symptoms early on. If it is the result of an inflammation, it can cause pain. Congenital mucosal cysts in the inner genital tract could reduce fertility by displacing growth.
To be confused with a cyst can be the aphtae, abscess, erosion, blister or blister formation (vesicula, bullae) and much more. Professional examination by a doctor or dentist is necessary for a correct diagnosis. As a rule, cysts are easily treated surgically.Of the types of mucous membrane described, the following cancers are prominent and important: stomach cancer (stomach carcinoma), cancer of the mucous membrane of the uterus (endometrial carcinoma), and cancer of the urinary tract (urothelial carcinoma).
Furthermore, malignant melanoma is also found on mucous membranes (melanomas of the mucous membranes) and the mucous membranes of the external genitals can be affected by cancer (vulva and penis carcinomas; squamous cell carcinomas). As already indicated, diseases of the mucous membrane such as inflammation (gastritis) are important risk factors for the development of cancer. 90% of these are so-called adenocarcinomas (see also: colorectal cancer), i.e. the cancer originates from gland cells.
Other important risk factors for stomach cancer are alcohol consumption and cigarette smoking, as well as colonization with the germ Helicobacter pylori. At the beginning of the disease, patients usually have few complaints, rarely unspecific abdominal pain, a feeling of pressure and fullness, and an aversion to meat. This is diagnosed by gastroscopy including taking tissue samples.
The only successful treatment is surgery with (in)complete removal of the stomach. Chemotherapy is only given in advanced stages. Cancer of the lining of the uterus is the second most common gender-specific cancer of women in Germany.
Mostly women between 60 and 70 are affected. It is now known that the most important risk factor is the intake of estrogens over many years (for example, through the contraceptive pill, etc.). This type of cancer becomes apparent at an early stage through painless vaginal bleeding and can be easily diagnosed with vaginal ultrasound.
Affected patients usually have good chances of recovery. The therapy consists of surgical removal of the uterus, fallopian tubes and adjacent lymph nodes as well as additional hormonal therapies (gestagens). Urothelial carcinoma tends to affect people over 65 and is actually only found in the bladder, the ureter, but rarely or never in the urethra.
This cancer makes itself felt through blood in the urine, while pain is absent for a long time. The most important risk factor is cigarette smoking. Depending on the stage and localization, it can be operated, in advanced stages chemotherapy is used.
A very rare form of malignant melanoma is an attack of the mucous membrane. It is very rare because the main risk factor is long-term exposure to UV light and the mucous membranes are not very exposed to it. It then develops mainly in the unkeratinized mucous membrane of the lower lip.
If a melanoma is detected early, the prognosis is usually outstandingly good with early surgical intervention. Cancer of the mucous membranes of the vulva (external female genitalia) is a very rare disease affecting middle-aged women. It becomes noticeable at an early stage through optical changes, itching, burning and pain, sometimes together with bleeding tears in the mucous membrane.
In early stages, surgery can be performed to improve the chances of recovery. Usually, however, the prognosis is poor and treatment is radiation or chemotherapy. So to speak, the counterpart in men is penis cancer.
In both cases the same cell layer is the origin of the cancer – the squamous epithelium. Penis cancer is a very rare cancer that is caused by a lack of hygiene and becomes noticeable early on by a hardening or swelling in the area of the glans. A small skin sample is taken to confirm the suspicion.
The only approach to healing is surgical excision of part or all of the cancer, in later stages also radiation and chemotherapy. Like the vulvar carcinoma, however, the prognosis is rather poor. Both are associated with infections of human papilloma viruses, the viruses that also cause cervical cancer and should be vaccinated against girls between 9-13.
Atrophy is the shrinking of tissue, either by decreasing the number of cells or by reducing the size of the cells. Examples of mucosal atrophies are: Atrophy of the nasal mucosa by nasal spray. The decongestant substance xylometazoline withdraws water from the mucosal cells, resulting in a temporary atrophy.
Excessive use (over a week) of nasal spray can cause permanent damage to the cells and long-term cell death. The mucous membranes of the female genital tract are subject to hormonal fluctuations during the fertile phases of life. For example, a lack of estrogen in old age causes atrophy of the vaginal mucosa.As this is accompanied by the death of glands and the mucous membranes become drier, they represent a lower protective barrier and the risk of infection increases.
There is no mucous membrane in the knee joint, but only several bursa synovialis. This is a bag-shaped cushion of joint fluid surrounded by thin skin. It lies between muscles and tendons on one side and is bordered by bone on the other side.
A bursa may be connected to the joint cavity or be separated from it. Its function is to improve the sliding of the tendons along a bone. Because the knee has so many muscle attachments, there are several bursae.
The largest is located under the patella (kneecap) and the femur (thigh bone) and is called bursa suprapatellaris. Other bursa located in the knee are: Bursa subtendinea musculi gastrocnemii lateralis, Bursa subtendinea musculi gastrocnemii medialis, Bursa musculi semimebranosi, Bursa subpoplitea and many more. They are each named after the structures with which they are directly surrounded.
Pemphigoid is the term used to describe skin diseases in which the upper layer of skin (epidermis) is lifted from the intact connective tissue underneath by blistering. They are found more frequently on normal skin than on the mucous membrane. The mucosal pemphigoid is a very rare, benign and chronic disease whose origin is unclear.
Blisters, erosions (superficial tissue defect or tear) and scars are formed on various skins. The conjunctiva (then called pemphiguus ocularis) are most affected, the further course of which can lead to drying and blindness of the eye. More rarely, it occurs in the mouth, genitals and oesophagus.
The similar “bullous pemphigoid” must be distinguished from this. Here, map-shaped redness (erythema) can be found, on which grouped vesicles and blisters are located. This is an autoimmune disease, i.e. a disease process in which the body’s immune system turns against its own structures.
