From Fork to Flush: The Story of Your Breakfast Quiz

Answer: Mouth

Digestion starts before you swallow a single bite. Your mouth produces saliva that contains enzymes like amylase, which begins breaking down starches. While eggs are mostly protein and fat, the chewing process still matters: it physically breaks the food down and mixes it with saliva, creating a slippery blob called a bolus. Your tongue then pushes the bolus toward the back of your throat.

Hopefully, your epiglottis (a little flap that covers your windpipe while swallowing) remembers to do its job. If it doesn't, that chewed-up egg may just make a guest appearance in your lungs. And if you're like me, your epiglottis too often takes a coffee break... while you're drinking coffee.

Answer: Esophagus

Say hello to the esophagus, a roughly 10-inch-long muscular tube whose only job is to hustle that egg bolus from your throat to your stomach. It does this by means of peristalsis, a series of coordinated muscle contractions that work kind of like a toothpaste tube being slowly squeezed from the bottom.

Helping things along is a generous coating of mucus. Once the bolus reaches the bottom, it runs into the lower esophageal sphincter (LES), a ring of muscle that usually stays clenched to keep stomach acid where it belongs. When you swallow, the LES relaxes and lets your food through to the stomach.

And if you're one of the millions who suffer from acid reflux or GERD, you may have the LES to thank. A weak or lazy LES can let stomach acid sneak back into the esophagus, which is about as pleasant as it sounds.

Answer: Hydrochloric Acid

That bubbling acid bath? It's hydrochloric acid (HCl), the same stuff used in rust removal, PVC production, and yes, toilet bowl cleaner. It's strong enough to dissolve metal, yet your stomach handles it like a champ (thanks to a thick layer of mucus that coats the stomach lining... shout-out to mucus again). It's what puts the burn in heartburn.

But acid's only part of the stomach's culinary demolition squad. There's also pepsin, an enzyme that specializes in slicing up proteins (like those yummy eggy bits) into smaller molecules called peptides. Meanwhile, the stomach's muscular walls churn and mash everything together into a thick, gooey slurry we lovingly call chyme. It's a little like dumping your chemistry set into a bread maker.

Once the stomach decides the mix is ready, it nudges the chyme toward the pyloric sphincter, a little muscular gate that only opens when the party's ready to move into the small intestine.

Answer: The size of your fist

When empty, your stomach is about the size of your fist: small, but ready for anything. And to prove Americans can use the Metric System, it holds around 50-75 mL (1.7-2.5 fluid ounces) when at rest, not even enough to enjoy a bowl of cereal! Fear not, friend. Your stomach is like a well-worn elastic band.

It can comfortably stretch to about 1 liter when you eat a big meal (roughly the size of a quart of milk), and in extreme cases (holiday buffet regret), it can expand to 4 liters, about a full gallon.

At that point, you're not just full, you're one miscalculated belch away from reliving your meal in reverse.

Answer: Duodenum

The duodenum (say it how you like; even doctors don't agree) is the first stretch of the small intestine, and it's basically another digestive blender. As the stomach releases small squirts of chyme, those acidic, sloshy remnants of your scrambled eggs, the liver and gall bladder dump bile in to emulsify fats. Meanwhile, the pancreas contributes a smorgasbord of enzymes that break down proteins, fats, and carbs into digestible bits. Not to be outdone, Brunner's glands coat the area with mucus to protect the delicate intestinal walls from acid like digestive Teflon. If you haven't guessed yet, mucus is definitely the unsung hero of the digestive process.

If you've ever suffered from pancreatitis, the duodenum is ground zero. The enzymes meant for food digestion get misdirected and start digesting your pancreas instead. It's even more painful than it sounds.

Answer: Bile

Bile is a yellow-green fluid made by your liver and stored in the gallbladder. It's released into the duodenum to help break down fats, not with enzymes, but by emulsifying them (kind of like soap breaking up grease). But here's the fun part: when bile pigments like bilirubin are broken down in your intestines, they turn into compounds (like stercobilin) that give poop its glorious brown color.

Without bile, your poop wouldn't just have trouble dealing with fats; it would look like something out of a ghost story: pale, clay-colored, and greasy. Yes, greasy ghost turds. It's not something you want to see for more than one reason. It often points to a bile duct blockage or liver trouble.

Answer: Villi

Villi are finger-like projections lining the walls of your small intestine, especially the jejunum, whose job is to maximize nutrient absorption. And just to be extra efficient, each villus is coated in microvilli, forming what's called the "brush border", which greatly increases the surface area available to grab nutrients from the gooey chyme sloshing past.

Thanks to the villi, your body can absorb amino acids (for repairing and building tissue), fatty acids and glycerol (for energy and storage), simple sugars (like glucose), and all those vital vitamins and minerals. If your cells can use it, the villi are scooping it up. Without them, you'd just poop out your breakfast whole (albeit in a frothier state) and that's hardly an effective use of your time.

Answer: Bacteria

The gut microbiome is mostly made up of bacteria, trillions of them in fact. Around half of the cells in your body are not you at all, but gut bacteria, and they adore your poop. These microscopic freeloaders (or symbiotic partners, if you must) play a huge role in digestion. By the time your food reaches the ileum, the nutrients have mostly been absorbed, but the bacteria step in to help break down anything that's left, like certain fibers and complex carbohydrates.

As we move closer to the large intestine, their numbers multiply, as bacteria tend to do. Some of them help synthesize vitamins like K and B12, while others produce gases (like methane and hydrogen) that may make their presence... known. And yes, your microbiome also contributes to the smell and color of your poop. Because even bacteria want a part in the big finale!

Answer: Colon

Welcome to the colon, the large intestine, where egg-chyme goes to evolve into full-grown poop (they grow up so fast!). The colon's job is to absorb water and electrolytes, transforming that runny soup into something more solid and considerably less appetizing. If this process goes too fast, you get diarrhea; too slow, and you get constipation. The colon is also where your gut flora, primarily bacteria, feast on whatever leftovers remain, particularly fiber.

These helpful microbes also produce vitamins like K and B12, and as a bonus, create gas as a by-product. This is why the colon is also responsible for one of life's most musical accompaniments: the fart. Let's all take a moment to appreciate the work of the colon and those microbes.

Meanwhile, haustra, the weird muscular pouchy segments of the colon, move and compact the poop into those adorable sausage-like lumps that may one day form the Holy Grail of bathroom success: the unified poop log. Finally, the sigmoid colon acts as a holding area, holding the poop while slurping out the last bit of moisture before it's show time.

Answer: Anal sphincter

Congratulations, you've made it to the rectum, the holding cell for your now fully-formed poop! As your poop enters, the rectal walls stretch like a balloon, activating stretch receptors that send a message to your brain: "It's go time!"

Thankfully, your body's not just a leaky faucet (anyone remember Olestra?). Enter the anal sphincters: two ring-shaped muscles that control the grand finale. The internal sphincter works automatically, while the external sphincter is under your control. That's right! It's the only thing standing between you and a deeply embarrassing moment during your morning commute, so speak no ill of it.

When the timing's right and you're near a porcelain fixture, you relax your external sphincter, sigh, and with or without a helpful push from your abdominal muscles, you complete the final step of this long, winding digestive journey. You did it! You turned eggs into poop! What a time to be alive!