Success Chemistry

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GlossarySuccess Chemistry Staff


Mucus or mucus is a viscous organic secretions of the mucous glands , which the mucous coats as a fine film.


Mucus is a protective covering for all non-horny or weakly keratinized epithelia . It forms a variable boundary structure between the environment and various internal and external body surfaces . The thickness of the slime layer is organ and situation-specific and varies between about 200 and 500 microns.


The composition and thus the properties of mucus can vary significantly in the various body regions (respiratory tract , gastrointestinal tract). This mainly concerns the viscosity , which is controlled by the content of certain glycoproteins , the so-called mucins . They form the most important, moisture-binding component of the mucus. In addition, mucus may contain, among other things, exfoliated cell material of the epithelium, immune cells, antimicrobial proteins (lysozyme) and antibodies (IgA).

General Mucus functions

  • Moisturization of the epithelial surface , protection against dehydration

  • Increasing the lubricity of tissues

  • Encapsulation and encapsulation of foreign bodies

  • Defense of microorganisms

Special Mucus Functions

  • Humidification of the respiratory air (nasal mucosa)

  • Protection against aggressive acids (gastric mucosa)

  • Conception regulation (vaginal mucosa, uterine lining)

Special types of mucus

  • bronchial

  • nasal mucus

  • cervical mucus


The consideration of mucus can give important clinical indications of diseases. The amount, viscosity and color of the mucus are assessed. Normal physiological mucus is clear and viscous.

  • Increased, low-viscosity mucus is usually an indication of a mucosal irritation, which is associated with increased secretion production , eg in allergic rhinitis .

  • Yellowish discolored mucus indicates a bacterial infection that results in an increased leukocyte content of the mucus.