Something I have wondered for a while is why have two different primary defense mediums, ie earwax and mucus, that perform the same function?

As far as I know, mucus and earwax are both part of the primary defense of an organism against disease and foreign particles, by trapping any pathogens or dust that enters the body.

My question is; Why does the body use earwax for ears and mucus for the lining of other entrances to the body, why not have mucus in the ears or earwax everywhere else? is there an advantage to have each medium in their respective places?


Unique and interesting question. It's hard to give a firm "why," but we can discuss the ways that the ear and other "holes" differ.

Mucous membranes line every tract into/out of the human body. Technically the ear is not a point of entry, as the tympanic membrane makes the external auditory canal a sort of blind pouch. The skin lining the ear is keratinzed skin. Most skin has keratin and is difficult to permeate. But mucous membranes are moist, thin, usually highly vascular, and generally easier to permeate. Disease often takes hold or gains entry at mucous membranes (respiratory infections, GI infections, etc). That is why mucus is so critical as it is protective and acts as a barrier and flushing-system.

Mucus requires some form of circulation, as it is a fluid. Once produced, usually at least some of the fluid is reabsorbed, and the remaining material is passed along until it exits the body. In the lungs, cilia bring it up to the throat and it is swallowed into the GI tract. In the nose, it drains down the back of the throat and is swallowed. In the eye, the fluid (which has mucus components to it) drains into a small tract that runs into the nasal passageway, which drains along with the other nasal mucus. Obviously saliva, which also has mucus components, is swallowed (2 liters a day of it, actually). In the genito-urinary tract, there is both reabsorption of some of the fluid components, but mainly flushing outwards when urinating. The GI tract reabsorbs almost all water components and the remnants pass with stool.

Mucus is produced by mucus glands. Cerumen (ear wax) is produced by sebaceous (oil) glands and apocrine (sweat) glands, but is primarily composed of shed skin cells from the ear canal. Sebaceous and apocrine glands are all over most of our exposed skin (except palms etc) so it stands to reason that they would be present in our ears as well.

Cerumen exits the ear several ways: all skin on the body sheds the top layers as new skin grows from underneath, and in the ear, the skin cells also migrate with a directionality from the tympanic membrane outwards. Head movements (like chewing) help dislodge things stuck to the walls.

I'll put in my plug here about NOT using cotton swabs (aka Q-tips) to clear your ears. It generally just pushes the wax deeper, except for the tiny bit you manage to get out. I've cleaned out tons of wax-impacted ear canals from people who use Qtips on themselves or their kids!!

If the ear were to use a mucous membrane system, the lower viscosity fluid would have to go somewhere. We would be weeping mucus from our ears unless there were a drainage system into the sinus passageways. The body conserves liquid, so we couldn't afford the constant fluid loss otherwise. The middle ear has a canal - the eustachean tube - which leads into the nasal sinus (although primarily to equalize pressure). But the external ear does not, so it's probably a good thing that we don't have mucous membranes in our ears.

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  • $\begingroup$ Wow fantastic answer! That helps a lot! Out of curiousity, what should we use to clean our ears? $\endgroup$ – J_mie6 Apr 14 '14 at 10:35
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    $\begingroup$ Ears mostly clean themselves, especially after you stop shoving it deeper inside with Q-tips. But I completely understand the desire to "help it along." This is gathered from recommendations from doctors in Audiology, Pediatrics, Family Medicine, and Emergency medicine - whom I have personally talked with about the topic. $\endgroup$ – DoctorWhom Apr 14 '14 at 17:02
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    $\begingroup$ In the shower, you can tilt your head to the side and let warm water and shampoo suds run into your ear. Switch sides. Then go back to the first ear, and tilt your head to drain the sudsy water. Then let it fill with clear warm water again, tilt and drain, and repeat until no soap is left in the ear. Soap residue also can be itchy and irritate. If you do this regularly, there won't be an accumulation of lots of wax. $\endgroup$ – DoctorWhom Apr 14 '14 at 17:18
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    $\begingroup$ If you really need more help, you can use a little vinegar (25% solution) in warm water and let it soak in there several minutes before rinsing in the shower. If it's to the point it's affecting your hearing or painful, call a primary care doctor, urgent care, or otorhinolaryngologist (ENT = Ear Nose and Throat specialist physician) and they can remove it for you. There's a wax-softening solution that can be purchased at the pharmacy (not sure if it's prescription), but it's best to avoid anything medicated unless you're symptomatic (hearing loss, pain) - make sure you ask a doc/pharmacist. $\endgroup$ – DoctorWhom Apr 14 '14 at 17:20
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    $\begingroup$ Important note: if you've had surgery on your ear, especially eardrum (tubes etc included) don't do anything without asking your doctor. $\endgroup$ – DoctorWhom Apr 14 '14 at 17:32

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