In by Raphikammer


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


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.