Mucus

Generality

The mucus is a stringy and viscous substance, more or less dense, which protects and lubricates the mucous membranes of the digestive, respiratory, urinary, visual, auditory and genital.

Functions

In the esophagus, for example, the mucus allows the sliding of the food bolus towards the stomach, where it protects the gastric walls from the corrosive effect of hydrochloric acid. A similar action is covered at the duodenal level, while in the rest of the small intestine the lubricating effect prevails again. Finally, in the large intestine, the mucus helps to compact the faeces and facilitates their evacuation.

Composition

The mucus is produced by the muciparous glands and by the muciparous goblet cells intercalated in some covering epithelia. It consists mainly of glycoproteins, collectively called mucins, which give it the characteristic slipperiness; it also contains antiseptic enzymes (such as lysozyme) and immunoglobulins.

Cervical mucus

In the cervical mucus specific antibodies can be found against the partner's spermatozoa, which prevent the fertilization of the egg cell. Also at this level, cervical mucus changes its consistency during the various phases of the menstrual cycle, becoming more prone to crossing spermatozoa during the ovulatory period.

Tracheal and bronchial mucus

In the trachea and bronchi, the abundant mucus secretion lubricates the inner surface of the respiratory tract and traps germs, inhaled foreign substances and other waste materials. Thanks to the coordinated action of millions of eyelashes, the mucus acts as a transporter of these unwanted substances to the outside, hindering their descent into the pulmonary alveoli (where they could become a cause of disease).

The cold slows down the ciliary beat temporarily, but often sufficient to favor the onset of infections; this is why some respiratory diseases are more frequent during the winter months.

Because of its protective and lubricating effect, the mucus is secreted in greater quantities during the phlogistic processes of the mucous membranes; when it takes on a yellow or greenish color it is an indication of a trapping of bacteria; when instead it maintains the fluid and whitish aspect it is more probable an irritated phenomenon not supported, or however only in part, by pathogens.