Mucus ( Latin “mucus”) is a viscous organic secretion , especially from mucous membranes , which usually serves to protect the organ surface from drying out, foreign particles or abrasion. Slime can also serve to encapsulate and encapsulate unwanted foreign bodies . The main structural components of mucus are the mucins .
Function in humans
As a sticky substance, mucus covers the epithelia as an organ-specific, protective covering. The thickness of the mucus in healthy people varies between 200 and 500 µm, depending on the organ, with the exception of the eye .
The mucus has a different protective function in different mucous membranes:
- Nasal mucous membrane produces the nasal secretion , which is used to trap dust from the air, humidify the inhaled air and recover moisture from the exhaled air.
- Oral mucosa / saliva : binding site for bacteria, enzymatic cleavage of polysaccharides , moistening to form chyme.
- The gastric mucosa protects against stomach acid
- The intestinal mucosa in the large intestine is in close contact with the intestinal flora . The mucus is an important part of the intestinal barrier function , which prevents a strong immune reaction with the intestinal flora and lubricates intestinal contents during transport and excretion.
- Uterine lining
- Eyes: Lubrication of eye movement, embedding, transport, binding and separation of dust and foreign objects
Examples of function in the animal world
- Slime from land-living nudibranchs and snails , which serves to protect and adhere to smooth surfaces.
Biofilms with bacteria sometimes appear in the form of slime. In stored diesel oil, in sewage pipes, in the flower vase, in a cave with methane and iodine as an energy source.
Fluid physics / rheology
Slimes are typical, non-Newtonian liquids with a gel character that can be "liquefied" by vigorous stirring.