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“Ok, everyone!” First Aid looked out onto the sea of hopeful medics squished into the auditorium chairs. “You should all be here for ‘Human Anatomy 101.’ If you are not in this class, I think you might be in the wrong lecture hall!”
One lone bot stood from their chair and tripped over everyone in their row trying to get to the door. All the optics followed them as the door slammed behind them.
“Well, glad we got that out of the way! Now that Cybertron is in an official alliance with Earth, the Senate wants us medics to have a passing understanding of the human body, just in case.” First Aid turned and flicked on the projector, lighting up the main screen with a slide deck. Thick, cutesy block letters spelled out ‘The Human Digestive System!!’ in pink. He turned back to the audience. “Today, we’ll be reviewing the digestive system!”
A lone hand went up in the audience, and a melodic voice rang out above the crowd, “What’s a digestive system?”
First Aid perked up. “Excellent question! A digestive system is the basic fuel processing system in humans. It’s similar to our tanks and fuel pumps!”
Aid clicked a button on his datapad and the slide changed to a new one. This one showed a multicolored diagram of a human torso, with the various innards labeled.
“The digestive system is essentially one long tube that all organic species have. It’s run by their autonomic nervous system, meaning they don't have to consciously think about processing their fuel, like how our coding takes care of running our fuel pumps and actuators!”
A smattering of nods went through the audience, as did some murmuring agreements.
“Now, digestion is broken up into four main parts; ingestion, digestion, absorption, and elimination.” First Aid clicked a button again and the screen changed to a blank white box. He picked up a stylus and began to draw along with his lecture. In thick, blocky letters, he spelled ‘Ingestion’ and underlined it twice.
“Smaller organic species can simply take food into their gastric cavities, release digestive juices to break down the food, and then absorb it into a food vacuole, but human systems are too complex for that. Humans, and many other vertebrate species, manually grind their food into a paste using their teeth and oral lubricant. They then swallow the paste, and like us, use peristalsis, the contracting and relaxing of the sphincters in the throat to push the food into their stomachs!”
Each point he made was accompanied by a little bullet point that described the topic in simple words. There were quite a few exclamation points.
“Next, digestion.” First Aid added a second header next to ‘Ingestion’, ‘Digestion’. “Digestion takes place in the stomach. A human stomach is similar to our fuel tank. Both are large, open cavities designed to hold fuel until the next stage of processing. But human stomachs have a liquid inside them. When the mashed-up food reaches the stomach, it is suspended in hydrochloric acid. A thick layer of mucus lines the stomach wall to protect it from the acid. This layer is called the muscosa!” He drew a little diagram of a stomach wall, similar to layers of metal stacked on top of each other. “The stomach wall is made of the mucosa, the mucus layer, the submucosa, a layer of connective tissues that connect the mucosa to the capillaries, the muscularis, a layer of smooth muscle, and the serosa, another layer of connective tissue. Fun fact, the mucosa layer of the stomach is renewed every 3 days!”
First Aid finished his diagram and spun back to the audience.
“Now, the muscularis is very important as it manually contracts the stomach and continues to churn and mix the food to increase surface area so the stomach acid can break down the food faster! Once the food is completely broken down, it becomes chyme!”
He walked back to the podium and flipped the slideshow again, this time to a slide labeled ‘The 4 Kinds of Food.’
“Unlike us, humans need four main kinds of nutrients to survive. Proteins, carbohydrates, fats, and amino acids. In addition to this, they need trace amounts of vitamins and minerals. Each nutrient is broken down in a different part of the body.”
He went back to his drawing and added a bullet point to ‘Ingestion’.
“Starch, a form of complex carbohydrate, is broken down by the enzyme amylase. Amylase is found in the saliva! In contrast to this, stomach acid contains pepsin. Pepsin cleaves proteins into smaller polypeptides and amino acids.” He flipped back to his diagram of the human torso and pointed out each location of digestion. “Pepsin itself is fascinating. Humans do this crazy thing called secretion, where fluid leaks out of their cells and into their stomachs. Parietal cells secrete the hydrogen and chloride ions to make the acid, while chief cells secrete pepsinogen, which gets activated to pepsin when mixed with the stomach acid and mucus!”
Various bots around the room had begun to shift uncomfortably, grossed-out expressions on their faces. A few doorwings were fluttering with nausea.
Next, let's move on to absorption!” First Aid flipped the slide deck back to his drawings and added a new header; ‘Absorption’. “Once the food is sufficiently broken down, it enters the duodenum, the first portion of the small intestine. The chyme mixes with digestive juices from the pancreas, liver, and gallbladder. The pancreatic juice contains more digestive enzymes, as well as bicarbonate.” With each new organ, a new subheader was added with more bullet points and even more exclamation points. “The liver provides bile salts. Bile salts are produced in the liver, but stored in the gallbladder, so they have a very close relationship, those organs. Bile salts interact with the hydrochloric acid and neutralize it so it can pass through the rest of the intestine without harming the human!”
A few more bots had joined the queasy-looking crowd, legs bouncing rapidly.
“As the food is broken down to its smallest components, it leaves the duodenum and enters the rest of the small intestine. The bile salts break up the large globules of fat, then lipase breaks down the triglycerides from that into fatty acids and monoglycerides! Now that all the food is broken down to its base components, it's absorbed by the cells of the small intestine. Most of the molecules and water are released into the bloodstream and taken to the liver via the hepatic portal vein.” First Aid went back to his torso slide and pointed out where the small intestine and the duodenum separate, then where the small intestine becomes the large intestine.
“Before we move on, I want to quickly review the various forms of digestion and their locations! Starch is broken down in the mouth, while other carbohydrates are broken down in the small intestine into glucose. The stomach digests proteins into peptides and amino acids, and fats are broken down into monoglycerides and fatty acids by the bile salts produced by the liver in the small intestine! These subunits of food are stored for long periods of time and can be broken down and built up into anything the body could need.”
The entire crowd had grown restless. Multiple mechanisms were fanning themselves with their datapads, noses pinched. A few had buckled over with their servos clutching their tanks.
“Finally, the large intestine and elimination!” Another header was added to the drawing slide. “Whatever couldn’t be digested is taken to the cecum, the beginning of the large intestine which absorbs any remaining water. The remaining large intestine compacts it into a bolus, which is then expelled from the anal sphincters as fecal material!”
That was the last straw for the crowd. A mech in the first row, a seeker with bright yellow wings, bent over their legs and purged all over the floor. Curdled energon spattered everywhere, including the legs of the bots sitting next to the seeker. The lecture hall burst into chaos as mechs clambered over each other to escape the scene, some yelling in disgust, others getting trampled in the fray. The seeker who had purged fled for the emergency exit, setting off alarms all over the entire building. Not even 30 seconds after the purging happened, the entire hall was completely empty.
Scratch that, not completely empty. A single mech, a manual labor frame by the looks of it, sat smack in the middle of all the seats, servo raised high.
“Do you hold office hours?”