Bodily secretions are part of daily life, but there are some you’d rather not have to think about. Not the obvious ones you deal with privately in the bathroom, necessarily, but the gunk that gathers behind your ears, the sticky stuff that appears in the corners of your eyes overnight, or the foul-smelling goo that festers in a fresh wound. Read on to find out what they have in common with soap, spittoons, and even one’s personality.
When pus, a thick fluid with a cream-like consistency, starts to appear in your body, it’s a sign your immune system has kicked in to fight an infection. This fluid is made up of dead white blood cells, technically known as leukocytes; fungi (not the edible kinds); and bacteria. It comes in a range of colors, including yellow, greenish, and white, and the difference in hue comes down to the neutrophils—the type of leukocyte in pus—reacting with the variety of bacteria present. Neutrophils are immune cells that are the first cells to react to infections. One type of bacteria, Pseudomonas aeruginosa, emits a green antibacterial protein called myeloperoxidase and smells awful. It’s no coincidence the etymology of the word pus includes the figurative meaning in Latin of bitterness or malice (putere, “to stink”) and the Sanskrit puyati, “to rot.”
These days most people don’t wait until they can smell something foul before consulting a doctor, but in the past, so-called “laudable pus” was seen as proof that a wound was healing well. This understanding dates back to ancient Greece, when Hippocrates equated white, neutral-smelling pus with health, and bloody, off-color pus with impending death. Today we recognize suppuration as a sign of an infection requiring antibiotics. Some pyogenic (pus-generating) bacterial infections, such as those caused by E. coli and Staphylococcus aureus, can even be fatal if left untreated. Another revolting historical titbit: The fluid portion of pus was once known as liquor puris, but it’s definitely not something you’d want to drink.
Variously known as dribble, spittle, or drool, saliva is a fluid containing electrolytes, mucus, and enzymes. It’s produced and secreted from the salivary glands in the mouth, and while you eat, the mucus in saliva holds all the chewed-up bits of food together and helps them slide down easily without damaging your throat on the way. Other functions include making dry foods taste, well, like something, because the liquid in saliva makes molecules soluble, releasing the flavor. Saliva also keeps your mouth clean, flushing away food debris without you knowing, so your mouth stays fairly fresh all the time. However, when you’re asleep you don’t produce as much, which can lead to bad breath in the morning.
Saliva has long been used as a diagnostic tool and even a form of therapy. Practitioners of traditional Chinese medicine examine saliva as a marker of overall health. The Bible recounts how Jesus restored the sight of a blind man by spitting on his eyes (the Romans used this method, too).
Whatever we think of it, our bodies produce saliva non-stop. Spitting is now considered gross in many countries, but in the 19th century—when chewing tobacco was more popular— it was common for American bars, hotels, and even banks to be equipped with spittoons. When the need arose, a person could eject their secretions neatly into a handy receptacle, rather than onto the floor.
Bile, a slightly alkaline fluid secreted by the liver, contains electrolytes, salts, lipids, cholesterol, water, and a yellowish pigment called bilirubin. Our bodies produce nearly a quart of bile (also called gall) per day, which is transferred to the gallbladder and eventually to the small intestine, where it helps digest fat.
Most people don’t think about bile unless they have a problem with their gallbladder, but once upon a time it was considered one of the four humors that determined a person’s temperament and features. In early Western physiological theory, the proportions of four bodily fluids—blood, phlegm, red or yellow bile (“choler”), and black bile (“melancholy”)—in a person’s body indicated their character; the ideal person had a perfect mix of them all. But too much yellow bile meant you were choleric and prone to aggression; too much black bile made you gloomy and downcast.
Cerumen is the fancy name for earwax and largely consists of dead skin cells, hair, and secretions from ceruminous and sebaceous glands located in the outer ear canal. It comes in a range of colors, including brown, orange, red, gray, or yellowish; it also keeps the skin of the ear canal clean and lubricated. It even protects it against harmful bacteria, fungi, and water. In the past, due to its waxy consistency, cerumen was used in lip salve and on wounds.
There are two types of cerumen: the brown, wet, waxy kind and the gray flaky kind. Which one you secrete depends on your genetic makeup. The wet type is more prolific in people of European and African heritage, while dry cerumen is found in people of Asian and Indigenous American descent.
The word smegma is derived from Greek, meaning “a detergent, soap or unguent.” Ironically, today it describes the crud found near the genitals, specifically around the clitoris and labial folds in women and under the foreskin in men. Usually whitish with cheesy consistency, smegma has a pungent odor, to put it mildly. It’s made up of all the things we naturally secrete to lubricate our nether regions, such as oils from sebaceous glands mixed with sweat, dead skin cells, and other matter. Smegma can develop into an unpleasant and itchy condition if the genital areas aren’t cleaned regularly.
Nineteenth-century novels are full of descriptions of people with rheumy eyes. Rheum—the gunk you find at the corners of your eyes when you wake up—comes from the Greek word rheuma meaning bodily flux or a stream or current. In literary terms, it just means a person has watery eyes.
Rheum is mucus discharged from the cornea or conjunctiva (the moist membrane protecting the eye and eyelid), as well as the nose and mouth. Blinking regularly keeps rheum from building up while we’re awake, but there’s no such cleansing when we’re asleep.
If you’ve ever scratched behind your ear and come away with a shiny waxy substance under your nails, don’t worry—you’ve just picked up some sebum. This gunk is basically skin oil, made up of a mixture of triglycerides, fatty acids, cholesterol, and other compounds that help keep your skin and hair moist. It’s produced by sebaceous glands found on almost all parts of the body, excluding the soles of your feet and the palms of your hands. Your face and scalp contain the highest concentration of these glands, so when you produce too much sebum, like during puberty, you end up with greasy hair and a face full of zits. It’s pretty much present at every stage of life—even in the womb, where it forms the thick white coating that protects and moisturizes the skin of the fetus.
People associate mucus with colds and all the gross material that comes out of your nose and throat: thick yellow phlegm, green snot, and disgusting brownish sputum. Yet mucus is simply a hydrated gel that’s almost all water. Only 5 percent of mucus is made up of mucin glycoprotein, a component protecting against damage by enzymes, microbes, and other chemical invaders.
Mucus is found in all parts of the respiratory system as well as in our mouths, throats, and gastrointestinal tracts. Our bodies produce about a quart of mucus a day, but we swallow most of it without noticing. Its job is to keep our sinuses and nasal passages clean and free of pathogens. Normally, mucus is clear or whitish, but in attack mode it takes on a yellowish green tint as neutrophils fight the pathogens. When you get sick, your body goes into overdrive, producing additional mucus to help flush the bacteria or viruses out of your system. No one likes to be sick and stuffed up from too much mucus, but if you produce too little of it, you’re more prone to infections.