Why does the Body Produce Mucus?

Christina Hall

The body produces mucus because the substance exhibits characteristics that help it prevent and fight infection. The body also uses it as a catalyst for certain reproductive functions and as a lubricant. The water-based liquid contains carbohydrates, salts, and protein, all needed by multiple organ systems. The primary proteins are encapsulated in a sugar substance that allows them to absorb large amounts of water, which produce the hydrating properties of mucus on which the body depends for homeostasis. Some proteins are antibodies that kick start the body’s immune system when a foreign invader is detected. Other proteins are antiseptic enzymes that kill the invader as soon as it comes into contact with phlegm.

Coughing may help to expel mucus.
Coughing may help to expel mucus.

The average body produces over 4 cups (1 liter) of mucus every day. The majority of it is produced by the respiratory system, where it serves several purposes. As air enters the nasal passageways, mucus traps larger particles that would clog the narrow airways. If any of the particles that gets trapped in the phlegm are pathogenic, the antiseptic and antibiotic properties work to kill the bacteria, virus, or fungi. It also aids in moisturizing the inhaled air, which keeps membranes within the body from drying out due to respiration.

The cells of the stomach lining produce mucus to protect the stomach from acid erosion.
The cells of the stomach lining produce mucus to protect the stomach from acid erosion.

Mucus also functions as the body’s most abundant lubricant. After particles are trapped during respiration, the body propels the lubricated substance, by way of small moving hairs called cilia, toward the stomach. In the stomach, acid can complete the process of killing any pathogens that may infect healthy cells. Cells within the digestive system also produce a large amount of mucus that is used as a lubricant to help propel food through the esophagus. The lining of the stomach also requires a lubricant layer, because while acid is useful in killing infectious particles, it will also eat away at the cells that form the lining if it is not adequately protected.

The female reproductive system relies on mucus to help regulate its cycle. During ovulation, the produced substance is clear and runny. The watery lubricant is conducive to sperm reception and fertilization. Post ovulation, it becomes thicker, and this substance, which also contains more antibiotic proteins, may prevent sperm from traveling any farther than the vagina, preventing fertilization. The male reproductive system produces it in conjunction with semen by way of the seminal vesicles, and this mucus contains carbohydrates and sugars that nourish the sperm during its life cycle.

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Discussion Comments


I think that mucus also helps us know when we are dealing with an infection.

I had my nose pierced last month. Everything seemed to be going fine until I noticed green mucus leaking out of the piercing. I knew that green mucus is a sign of infection and I went to the doctor. My doctor prescribed me antibiotics and the infection cleared up in no time.

If there was no such thing as mucus, I would not have know that my piercing was infected until the infection had spread and gotten worse. So mucus is a good thing.


@fBoyle-- Cervical mucus during ovulation helps sperm move into the uterus and also helps sperm stay alive longer to increase the chances of fertilization. It's the vaginal environment that has an acidic pH but cervical mucus and the mucus found in semen help protect sperm from this environment.

Some doctors say that cervical mucus kills unhealthy sperm so that they cannot fertilize an egg. I guess it's body's natural way to protect against genetic deformities in the fetus.


I always thought that cervical mucus reduces the chances of fertilization because it's acidic and kills sperm. So it's the opposite?

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