Just the name itself will make you giggle. It's a great word that conjures visions of slime and unpleasantness. It is perhaps the most annoying part of having a cold or allergies. Mucus, however, plays a very important role in defense of our bodies and our health. In fact, it's high time mucus got a lot more respect. First, there are some amazing facts about mucus that are worthy of respect. Humans produce about a liter of mucus every day, whether they are sick or not. Bony fish and some invertebrates (snails or slugs) also have mucus cells on the outside of their body. This external mucus creates a protective coating that prevents predators' toxins from doing harm. Humans produce mucus to protect our stomachs, our lungs, and several other systems.
We tend to not like mucus because it is a considered a symptom or sign that something is wrong. We usually only see it when we are sick, and so we tend to dislike it. According to Michael M. Johns, III, MD, however, "mucus is incredibly important for our bodies." Johns, an assistant professor at Emory University, calls mucus "the oil in the engine" of our bodies. Without mucus, our engines, or bodies, would freeze up and stop working properly.
Furthermore, mucus is not just the nasty gunk you see when you are sick. It lines the tissues in your mouth, your nose, throat, and lungs. It also is crucial in protecting your digestive system. Mucus puts a protective coating over the surfaces of these tissues, keeping them moist. Most of the time we don't notice mucus is making our lives better. It does its job quietly, making everything run smoothly, keeping our inner tissues soft and flexible enough to fight off invaders.
Occasionally, though our mucus-making membranes go into overdrive. If you eat a hot pepper, your mucus membranes in your mouth and throat start producing extra mucus to protect you. If you come into contact with pollen, you may get a runny nose and start sneezing and coughing. When these things happen, your mucus systems start making more fluids to wash away the irritating particles. Mucus also has some antibodies that increase our ability to fight off bacteria and viruses.
It's hard to appreciate what is essentially slime, but we have mucus for some very good reasons. It helps to keep us healthy and lets us know when our bodies are under attack. We would be wise to respect what our bodies do to keep us safe. So the next time you find yourself reaching for a tissue, remember mucus is your friend and ally.

Mucus is a great word, not only because it gives name to an important bodily function, but also because it is one of those words that simultaneously makes you feel grossed-out and giggly. Other words for this powerfully important human-health tool include slime and phlegm. Slang words for mucus include boogers and snot. All of these words have the same giggle-power, simply from the combination of consonants and vowels. By the way, mucus is an old word; it's been around since the mid-1600s and has roots back to Latin (mucere, to be moldy or musty) and Greek (myxa, mucus). While you may assume that words like snot and boogers are relatively new slang terms, they are not. Snot dates to 1560 and comes from an Old English word, gesnot, and has the same root as the word snout. The word booger is not quite as old but has been in use since the 1890s.

Just the name itself will make you giggle.
What purpose does the word giggle serve in this sentence?

a. It explains the text will focus on the names of bodily fluids.
b. It implies the passage information will not be very important.
c. It increases the connection to the discussion about bodily functions.
d. It lets the reader know the tone may not be very serious.