The mucous membranes are linings of mostly endodermal

Germ layer

A germ layer, occasionally referred to as a germinal epithelium, is a group of cells, formed during animal embryogenesis. Germ layers are particularly pronounced in the vertebrates; however, all animals more complex than sponges produce two or three primary tissue layers...

 origin, covered in epithelium

Epithelium

Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...

, which are involved in absorption and secretion

Secretion

Secretion is the process of elaborating, releasing, and oozing chemicals, or a secreted chemical substance from a cell or gland. In contrast to excretion, the substance may have a certain function, rather than being a waste product...

. They line cavities that are exposed to the external environment and internal organs

Organ (anatomy)

In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...

. They are at several places contiguous with skin

Skin

-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

: at the nostril

Nostril

A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...

s, the mouth

Mouth

The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....

, the lip

Lip

Lips are a visible body part at the mouth of humans and many animals. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech...

s, the eyelids, the ear

Ear

The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....

s, the genital area

Sex organ

A sex organ, or primary sexual characteristic, as narrowly defined, is any of the anatomical parts of the body which are involved in sexual reproduction and constitute the reproductive system in a complex organism; flowers are the reproductive organs of flowering plants, cones are the reproductive...

, and the anus

Anus

The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...

. The sticky, thick fluid secreted by the mucous membranes and glands is termed mucus

Mucus

In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...

. The term mucous membrane refers to where they are found in the body

Body

With regard to living things, a body is the physical body of an individual. "Body" often is used in connection with appearance, health issues and death...

 and not every mucous membrane secretes mucus.

The glans clitoridis, glans penis

Glans penis

The glans penis is the sensitive bulbous structure at the distal end of the penis. The glans penis is anatomically homologous to the clitoral glans of the female...

 (head of the penis

Penis

The penis is a biological feature of male animals including both vertebrates and invertebrates...

), along with the inside of the foreskin

Foreskin

In male human anatomy, the foreskin is a generally retractable double-layered fold of skin and mucous membrane that covers the glans penis and protects the urinary meatus when the penis is not erect...

 and the clitoral hood

Clitoral hood

In female human anatomy, the clitoral hood, , is a fold of skin that surrounds and protects the clitoral glans. It develops as part of the labia minora and is homologous with the foreskin in male genitals.-Variation:This is a protective hood of skin that covers the clitoral glans...

, are mucous membranes. The urethra

Urethra

In anatomy, the urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids out of the body. In males, the urethra travels through the penis, and carries semen as well as urine...

 is also a mucous membrane. The secreted mucus traps the pathogens in the body, preventing any further activities of diseases.

Some examples of mucosa

• Buccal mucosa
• Esophageal mucosa
• Gastric mucosa
  Gastric mucosa
  The gastric mucosa is the mucous membrane layer of the stomach which contains the glands and the gastric pits. In men it is about 1 mm thick and its surface is smooth, soft, and velvety...
  
  
• Intestinal mucosa
• Nasal mucosa
  Mucous membrane of nose
  The nasal mucous membrane lines the nasal cavities, and is intimately adherent to the periosteum or perichondrium. It is continuous with the skin through the nares, and with the mucous membrane of the nasal part of the pharynx through the choanae...
  
  
• Olfactory mucosa
  Olfactory mucosa
  The olfactory mucosa is located in the upper region of the nasal cavity and is made up of the olfactory epithelium and the underlying lamina propria, connective tissue containing fibroblasts, blood vessels, Bowman's glands and bundles of fine axons from the olfactory neurons.The mucus protects the...
  
  
• Oral mucosa
  Oral mucosa
  The oral mucosa is the mucous membrane epithelium of the mouth. It can be divided into three categories.*Masticatory mucosa, para-keratinized stratified squamous epithelium, found on the dorsum of the tongue, hard palate and attached gingiva....
  
  
• Bronchial mucosa
• Uterine mucosa
• Endometrium
  Endometrium
  -Function:The endometrium is the innermost glandular layer and functions as a lining for the uterus, preventing adhesions between the opposed walls of the myometrium, thereby maintaining the patency of the uterine cavity. During the menstrual cycle or estrous cycle, the endometrium grows to a...
  
   is the mucosa of the uterus
  Uterus
  The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
  
  
• Penile mucosa

See also

• Mucin
  Mucin
  Mucins are a family of high molecular weight, heavily glycosylated proteins produced by epithelial tissues in most metazoans. Mucins' key characteristic is their ability to form gels; therefore they are a key component in most gel-like secretions, serving functions from lubrication to cell...
  
  
• Mucocutaneous boundary
• Mucociliary clearance
  Mucociliary Clearance
  Mucociliary clearance, also referred to as mucociliary apparatus or mucociliar clearance , derived from mucus , cilia and clearance describes the self-clearing mechanism of the bronchi.The main bronchi down to the alveoli are lined with a respiratory epithelium...
  
  
• Mucosal immune system
  Mucosal immune system
  The mucosal immune system is that portion of the immune system which provides protection to an organism's various mucous membranes from invasion by potentially pathogenic microbes...
  
  

External links

- "Mammal, whole system (LM, Low)"

• http://www.mucusmanagement.org.uk