How erotic and educational.
Great one!

Chapter 6: Small Intestine

Brian found that the space inside the small intestine was much more cramped than it had been inside the stomach. "Brain has officially entered the small intestine. Can anyone tell me the parts of the small intestine?" Dr. Bentenson asked.
"The duodenum, the jejunum, and the ileum." said a badger.
"Correct. And what part is Brian in right now?"

"The duodenum."
"Correct. And what is the function of the duodenum?"
"I'm not sure."
"Can anyone else tell me?"
"The duodenum receives digestive juices from the liver, gallbladder, and pancreas. Hormones in the duodenum signal to these organs to release the juices when food is present. It is comprised of four segments. The first segment is called the superior segment. It contains the duodenal bulb or cap. The duodenal bulb connects to the liver via the hepatoduodenal ligament. This connection allows nutrients to move from the small intestine to the liver. It also allows the duodenum to receive bile from the liver. The descending duodenum is located above the right kidney and extends down. It connects to the pancreas via a small tube called the pancreatic duct, which feeds enzymes into the duodenum to help break down food. The common bile duct carrying bile from the liver also enters this second part of the duodenum. The transverse duodenum, commonly called the inferior or horizontal part, extends horizontally across the abdomen. It is located in front of the aorta and travels from right to left, behind a network of blood vessels. The ascending part of the duodenum extends up, passing atop or slightly to the left of the aorta. This final segment leads to the jejunum, the middle portion of the small intestine. The walls of the duodenum are composed of four layers. The mucosa layer is the innermost layer made up of mucus glands and microvilli, the fingerlike projections that work to absorb nutrients. The submucosa layer is primarily composed of connective tissue. It has a rich network of blood vessels and nerves traveling the length of the duodenum. This submucosal layer also contains Brunner’s glands, which secrete mucus to help enable food to move through, and bicarbonate. Bicarbonate is a chemical that neutralizes acid in the chyme ahead of further digestion. The muscularis externa layer is made up of smooth muscle tissue that's responsible for contractions in the GI tract. The muscles churn the chyme, mix it with digestive enzymes, and cause the food to move into the jejunum. This muscle movement is called peristalsis. The serosal layer, which is the outermost layer of the duodenum. It is composed of squamous epithelium, a single layer of flat cells that provides a barrier to other organs. " said a cat, who was one of the top students in the class.
"Correct, Caleb. And we should get a sight of these juices soon as Brian moves further into the superior segment."

A few minutes later, a thick greenish-brown substance began to coat Brian. it was dripping out of some duct and into the duodenum. "Yuck! Where is this stuff coming from?" Brian grumbled.
"Can anyone answer that for Brian?" said Dr. Bentenson.
"It's bile. It is made from water, bile acids, cholesterol, phospholipids, bile pigments (such as bilirubin), and electrolytes. It is important in enabling the body to digest and absorb fats and fat-soluble vitamins like vitamins D and K. It comes from the biliary system. Bile is made in the liver cells and flows from the liver into a system of ducts located inside and outside of the liver. These ducts function to collect the bile. Once collected, the bile travels to the right and left hepatic ducts. It then flows from the right and left hepatic ducts into the common hepatic duct, then into the cystic duct, which is connected to the gallbladder. From the cystic duct, the bile flows into the common bile duct. The common bile duct is located where the common hepatic duct and the cystic duct join. It runs from the liver through the pancreas and into the duodenum. The lower portion of the common bile duct joins the pancreatic duct before entering the duodenum. This is where pancreatic juices containing digestive enzymes enter the biliary system. Bile is excreted into the duodenum through a muscular opening called the sphincter of Oddi. The sphincter of Oddi relaxes to allow bile to enter the duodenum. Once the bile enters the duodenum, it begins to break down ingested fats. Only half of the bile ends up in the duodenum, while the other half travels into the gallbladder through the common bile duct. The bile received by the gallbladder is stored in the gallbladder for future use. Once bile is stored in the gallbladder, it isn’t released until a large meal is eaten and a hormone called cholecystokinin is secreted. This hormone stimulates the release of bile to begin the process of breaking down fats." answered a chicken
"Very good. Can anyone tell me about the function of the liver, gallbladder, and pancreas?"
"A snake's liver is elongated and is divided into several separate lobes. The liver is located in the upper right-hand portion of the abdominal cavity, beneath the diaphragm, and on top of the stomach, right kidney, and intestines. The liver contains about 13% of the body's blood at any given time. The liver regulates most chemical levels in the blood and excretes a product called bile. This helps carry away waste products from the liver. All the blood leaving the stomach and intestines passes through the liver. The liver processes this blood and breaks down, balances, and creates the nutrients. The liver produces bile, produces certain proteins for blood plasma, and also produces cholesterol and special proteins to help carry fats through the body. It converts excess glucose into glycogen, it regulates the blood levels of amino acids, processes hemoglobin, and coverts ammonia to uric acid. In a snake, there is a considerable distance between the caudal tip of the liver and the gallbladder.
"The gallbladder has three parts, the fundus, the large end that stores bile, the body, and the neck. The gallbladder has multiple layers, such as the ephithelium, the lamina propia, the muscularis, the perimuscular tissue, and the serosa. The gallbladder is located below the liver. It stores and produces bile. If you eat food that contains fat, then the stomach and small intestine will release cholecystokinin, a hormone that causes your gallbladder to contract. This contraction caused half to three-fourths of the bile stored to go into the small intestine. The bile helps break down the fat so that the body can use it for energy.

"The pancreas serves as part of the digestive system and the endocrine system. It produces insulin when the glucose level gets too high and glucagon when the glucose level gets too low. It produces lipase to digest fats, amylase to digest carbohydrates, chymotrypsin and trypsin for digesting proteins. The pancreas produces enzymes as soon as food reaches the stomach. These enzymes travel through a series of ducts until they reach themain pancreatic duct. The main pancreatic duct meets the common bile duct, which carries bile from the gallbladder and liver towards the duodenum. This meeting point is called the ampulla of Vater. Bile from the gallbladder and enzymes from the pancreas are released into the duodenum to help digest fats, carbohydrates, and proteins so they can be absorbed by the digestive system." answered the chicken, who was a straight-A student, even smarter than Caleb and ever more of an insufferable know-it-all, again.
"Excellent, Henrietta, as always." said Dr. Bentenson.

"Now that we've reached the small intestine, it's time to talk about the next stage of digestion after mechanical and chemical digestion: absorption. Can anyone define that?"
"During the process of absorption in the digestive system, the nutrients from the food are absorbed into the bloodstream and transported to the cells throughout the body. The following are the different events that take place during absorption:
Transport of nutrients: The nutrients are transported across the intestinal wall and into the bloodstream. This process is facilitated by the presence of transporters that help move the nutrients across the cell membrane.
Diffusion: Some nutrients, such as water and small lipids, can diffuse across the cell membrane without the need for transporters.
Active transport: Some nutrients, such as glucose and amino acids, require energy to be transported across the cell membrane. This process is called active transport.
Endocytosis: Large molecules, such as proteins, are absorbed by the cell through a process called endocytosis. In this process, the cell membrane engulfs the molecule and forms a vesicle around it." answered Henrietta.
"Correct."

As the class and Dr. Bentenson talked, Brian took notes. He moved through the rest of the duodenum over the next 30 minutes. There wasn't much in there, except for bile, and there was lots of that. "Filthy stuff! Good thing I'm wearing this suit!" he said. He noticed that the food was being broken down even further by the bile. He knew that, in a later part of Slybella's small intestine, a bunch of this would be absorbed. Unfortunately, he would be left with what was not absorbed, the waste products. Finally, he could tell that things were changing. "I think I'm moving into the jejunum." he said.
"Yes, you would be. You'll be in this segment much longer than in the duodenum. Probably for about five hours." said Dr. Bentenson. "Can anyone tell me the function of the jejunum?"
"The jejunum is the middle portion of the small intestine, connecting the first portion of the small intestine (the duodenum) with the last section (the ileum).The cells lining the jejunum are responsible for absorbing the nutrients that are released from food during the process of digestion. To help facilitate this process, the surface area of the small intestine is increased many-fold due to the presence of villi, or finger-like projections. The cells lining these villi absorb dietary nutrients including sugars, amino acids, and fatty acids. These nutrients are absorbed from the intestinal cavity (or lumen), travel across the jejunal cells, and then are passed into the bloodstream, where they can be carried to distant parts of the body and used to support cell metabolism and growth." Caleb recited.
"Correct."
"These villi are annoying. They're poking me everywhere!" Brian grumbled.
"They line most of the small intestine, so you're just going to have to get used to them." Dr. Bentenson replied.
"Of course!" Brian sighed.
"Can anyone tell me how villi absorb nutrients?" Dr. Bentenson asked.
"Villi are great at absorbing nutrients because they increase the surface area of the inside of small intestine. Each villus is composed of a meshwork of capillaries and lymphatic vessels (called lacteals) underneath an ultra-thin layer of tissue. This special structure makes it possible to pull macro- and micronutrients out of your meals and send them to the bloodstream. Water also helps with this process. The small intestine uses a chemical process called diffusion to extract nutrients. Diffusion moves water and water-soluble compounds across barriers, like the villi in the small intestine. Some nutrients can go directly into the bloodstream with no problem. Others like fatty acids, need a bit of extra help. Bile from the liver mixes with fats to break the fats down into fatty acids. Then the villi absorb them and sent them into lacteals. These lymphatic vessels transport the fat-soluble compounds to the liver. That’s where they are stored and released in the body as needed. The fatty acids help to build cell membranes." said a dog.
"Very good."

As this was Friday,. there was, officially, no school the next two days. However, at the end of each class, Dr. Bentenson offered extra credit to any and all students who would come in on the weekend to further observe Brian's progress. Most students in all the classes eagerly took advantage of this opportunity. As the day drag on, Brian watched as the villi absorbed some of the chyme, leaving the leftover non-useful bits behind. The villi were a hassle for Brian. Not only did they poke at him, which, even with the suit, was extremely uncomfortable and was still felt, much like contractions inside a climaxing vagina would still affect a penis inside a condom. And speaking of penises, Brian's was tickled to ejaculation when he had it pulled out for just two minutes so that he could empty his bladder. He made a mental note to urinate in his pants and underwear (which he knew he'd be discarding when this was all over anyway)) from now on until he was outside of Slybella's body. (for he knew that snake waste would be almost as bad as villi on his member.)) And speaking of feces, when he went number two, he got it splattered all over him as the villi, failing to absorb it, rubbed it all over him. He wasn't going to have a bowel movement again till in the colon, where he knew more poop wouldn't really hurt anything. Eventually, with only thirty minutes to go before the end of the final class period of the week, he finally was reaching the end of the jejunum. "Looks like I'm heading to the ileum." Brian said.
"Good. Since this is the largest section of the small intestine, you should be in here till sometime tomorrow morning." Dr. Bentenson said.
"All fine with me. After the ileum, I end up in the colon with her poop, so I'm in no hurry."
"Could someone tell me about the ileum?" Dr. Bentenson asked.
"The ileum's, like the jejunum's, primary function is to absorb nutrients into the bloodstream. It absorbs Vitamin B bile salts and whatever else can be absorbed that wasn't by the jejunum. Its endpoint is the ileocecal valve, which leads into the large intestine." answered a gerbil.
"Correct."

Time seemed to slowly go by for Brian. The small intestine seemed an endless tunnel filled with little tentacle-like structures that pulled at him and absorbed the nutrients. The deeper he went, the more noticeable the smell of the intestinal gas became, even with his suit. Despite the annoyance of the villi, he was very tired by this point, having gotten so little sleep, and slept a lot of the night. He was woken around 6 in the morning on Saturday. He could still see villi around him. He took notes on what he saw as well as reviewed all the notes that he had taken so far. There were indeed a lot of them, but, with all this time to study while inside Slybella, he was confident that he could pass this test with ease. A few hours later, he could hear people moving around outside the snake. It seemed that most of the classes had showed up for the extra credit. "Brian, where are you?" someone asked.
"Still in her small intestine."
Several minutes later, he suddenly noticed something up ahead. It had to be the ileoceca valve. A few minutes later, he was pushed through it, leaving the small intestine and entering the large intestine.

Chapter 7: Large intestine

Contrary to what Brian had expected, there wasn't a bunch of poop waiting for him as he entered the cecum. Instead, it was just the leftover food that followed him out of the small intestine. "I'm in the large intestine. I thought there'd be poop here." Brian said.
"First, let's discuss the sections of the large intestine, and then we can get to Brian's question about poop." said Dr. Bentenson.
"The large intestine is divided into three sections, the cecum, the colon, and the rectum. The colon is broken down into four segments, the ascending colon, the transverse colon, the descending colon, and the sigmoid colon: The cecum acts as a receptacle for the liquid products passed into the large intestine. More than just a reservoir for liquids, the cecum is responsible for the absorption of salts and electrolytes into the body from liquids. The muscle tissue of the cecum contracts, causing the liquid products to churn. This churning extracts salts and electrolytes, such as sodium and potassium. These salts are then absorbed into the mucus membrane of the cecum. Another important function of the cecum is to lubricate the solid waste that passes into the large intestine, mixing this waste with mucus. A thick mucus membrane lines the cecum, and produces the mucus necessary to lubricate the solid waste. The large intestine extracts liquid from the waste products, making it necessary for the mucus to lubricate the solid waste and allow it to pass through the rest of the large intestine. Bacteria aid in the breakdown of the food to help remove nutrients from the leftover food, to help cut down on the amount of waste that goes to the cloaca. Near the end of the cecum is the appendix." said a rabbit.
"And what about the poop? This doesn't look like the stuff that comes out my anus, except when I have diarrhea. Is Slybella sick?" Brain asked.
"We'll get to that now." said Dr. Bentenson. "Could you tell Brian, Franklin?"
"No, Slybella isn't sick. The reason the waste is like this is that the water hasn't been removed from it yet. That will happen as it goes through the large intestine." the rabbit answered.
"Correct."

PHHHHHHHBT! PHHHBT! Slybella broke wind. "The snake farted!" several in the class laughed.
"Can anyone tell me what farts are made of?" Dr. Bentenson asked.
Stu, a skink who was always making fart jokes, answered "Farts are made of gas that is swallowed or produced by bacteria in the digestive system. A fart is composed of mostly nitrogen, hydrogen, carbon dioxide, methane, and oxygen. Only a small amount of a fart contains sulfur compounds, which are responsible for the foul smell."
"Correct."
Brian traversed through the rest of the cecum over the next hour or so. As the rabbit had said, more nutrients were absorbed from the liquid. And he was coated by the mucus, making him gladder than ever that he had the suit, keeping him safe from the fecal slime. Eventually, he came to the colon. By this point, some water had been removed from the liquid-like waste that had left the ileum and now bore a closer resemblance to the feces that came out his anus during defecation. The smell was getting worse and worse too. "Why does this shit stink so bad?" he asked.
"It's because of the bacteria in there. They help with the breaking down of the final nutrients in the large intestine and also are responsible for creating the odor of the feces. In addition, Slybella is an obligatory carnivore, which means....?"
"She must eat meat as the entirety of her diet." Brian answered.
"Correct. And meat tends to have a certain odor to it as it reaches the end of the digestive tract."
Brian slowly moved throughout the digestive tract. Though he knew the large intestine, despite its name, was only a fraction of the size of the small intestine, he seemed to be moving slower in here than he had been in the small intestine. "Why is it taking so long?" he asked.
"Because it absorbs water. If it didn't, you'd have really runny stool."
"Yeah, I hate when that happens. And I'm glad it's not happening when I'm inside a snake's colon."
"You probably won't reach the cloaca till tomorrow afternoon, I'm afraid."
"And then Slybella will shit me out?"
"Unfortunately, no. Snakes normally have one large meal a week or so and don't release stool and urates until that has passed all the way through. That can take at least a week."
"At least a week? You mean I could be stuck inside her longer?"
"Theoretically. However, Slybella normally voids her cloaca once a week, give or take a couple of hours. So you should be out by Monday during the last class period at the latest."
Brian felt relieved about that. It wouldn't do to be stuck inside the snake longer and have his cover story to his parents and girlfriend concerning his absence be blown by being missing extra days.

After travelling for half the day in the large intestine, he began to notice, in addition to the brownish colored feces, which had begun to harden, sometimes around Brian, though he pushed it off as best he could, inside the colon, there were also yellowish and whitish substances that he couldn't identify. "Is Slybella sick? These poops don't look like the rest." Brian said.
"That's because they aren't feces." said Dr. Bentenson.
"Then what are they and where did they come from?"
"I'll answer your first question first, and that can lead into answering your second. They are urates. Uric acid."
"Urates? What is that?"
"It's different from urine due to the low water intake of snakes. Snakes' bodies are designed to conserve water. Like mammals, a snake’s kidneys filter waste products from its blood. The two kidneys are elongated in snakes, one fixed closer to the head than the other. Once the kidneys have done their job, the urine matter is concentrated and transported through ureters to two cavities in the snake’s body. First, it goes to the urodeum, which collects urine and is also used for reproductive purposes. Then it goes to the coprodeum and is, to help conserve water, moved back up into the colon."
"Urodeum, coprodeum, what are they?"
"Parts of the cloaca. But we'll get to that later. While we're on the subject of the excretory system, can anyone tell me how the excretory system works?"
"The body takes nutrients from food and converts them to energy. After the body has taken the food components that it needs, waste products are left behind in the bowel and in the blood. The kidney and urinary systems help the body to eliminate liquid waste called urea, or in the case of us birds and snakes, uric acid, and to keep chemicals, such as potassium and sodium, and water in balance. Uric acid is produced when foods containing protein, such as meat, Slybella's main diet, are broken down in the body. Uric acid is carried in the bloodstream to the kidneys, where it is removed along with water and other wastes in the form of uric acid. It then goes down the ureters to the urodeum." said Henrietta.

"Correct."
"Henrietta, why are you here? You already are acing this class!" Brian asked in annoyance.
"Because, I figure that every little bit of extra credit can't hurt me."

Brian spent the rest of the day and the following morning in the large intestine, descending deeper and deeper. Around the afternoon, he was nearing the rectum. "The rectum is normally the endpoint of the digestive system, save the inner and outer anal sphincters and the anus. But Slybella is a snake so things should be a bit different for you." said Dr. Bentenson.
"You mean the cloaca?"
"Yes. After you drop to the bottom of the rectum, you should fall into the first part of it."
A few minutes later, Brian reached the rectum, going down the final bend of the large intestine. As he'd been informed, he didn't rest against an anus, but instead fell into another chamber, one that was full of feces and urates. He'd reached the cloaca

Chapter 8: The Cloaca

"Is this the cloaca?" Brian asked.
"Part of it. You're in the proctodeum, where you will remain until you are excreted."
"Are there any other parts to the cloaca?"
"Henrietta, since you have a cloaca, can you answer Brian's question?"
"Sure thing. The cloaca can be divided into the coprodeum, urodeum and proctodeum by complete annular folds. Some urinary excretions arriving in the cloaca become incorporated with the ingesta and move in a retrograde fashion to the caeca, increasing the absorption of water and electrolytes from the urinary waste. The coprodeum is the most cranial division of the cloaca. It is the continuation of the colon where faeces are stored. It is bounded by the coprourodeal fold. It can be stretched by the faecal pressure so the central opening is everted through the vent.The urodeum is the middle part of the cloaca. It is caudal to the proctodeum fold. It has the ureteric opening in the dorsolateral wall above the papilla of the deferent duct/oviduct opening. Slybella's digestive system is like mine, though I have a crop and a proventriculus and a gizzard and she only has a stomach."
"Correct Henrietta, as always."
"So, the urates are coming from below, in the urodeum?"
"That's correct, Brian."
"So, I just sit here until Slybella shits me out?"
"I suppose, unless you'd like to explore the other parts of the cloaca."
"Probably not at this time. I've about had enough of the snake digestive tract and don't plan to explore it till I'm excreted that way."
"Very well then. You'll just have to wait till nature takes it course."
"You know, Slybella's life must be very dull, only eating, drinking, and pooping. Nothing else to do."
"I thought as much. Which is why I've ordered her a friend. He should be here by Monday morning."
"Good, she seems lonely."
And so Brain languished inside the cloaca, as well as the large intestine, for true to what Henrietta had said, the cloaca sometimes sent the wastes, along with him, back into the colon, all the rest of that day and into the following day. Hopefully, he thought, as this day dawned, it would be his last inside the snake. As the class filed in, Dr. Bentenson said "Slybella's new friend has arrived."
"What is it?" Brian, who was still inside Slybella's cloaca, and thus couldn't see, asked.
"A male python." answered Caleb.
"Now, we can see class that the excretory (for liquid, or in Slybella's case, semi-solid urates, waste) and egestion (which includes defecation, the last stage of the digestive process)) are combined in the cloaca. Slybella's cloaca is beginning to bulge out, in an eversion. This process of waste elimination is called cloacal ventilation. This brings us to the third system that ends in the cloaca: the reproductive system. Slybella is laying eggs."
"But you just got the male. How could she be pregnant already?" Brian asked.
"Unfertilized eggs. I lay them too." Henrietta answered.
Brian, feeling curious, moved down through the waste and poked his head and his shoulders into the urodeum to get a better look. He could see an egg coming from Slybella's vagina. It was bulging out from her cloacal slit, and he could see a faint bit of light, which blinded him, as he'd only had the light from his phone and flashlight inside the snake. The egg fell out, followed by several others. Eventually, Slybella stopped laying. "Fascinating!" Brain said, snapping pictures.
"Can anyone tell me how the snake lays an eggs?" Dr. Bentenson asked. To nobody's surprise, Henrietta answered again. "Oviparous or egg-laying snakes make up the majority of snake species. Eggs grow in the oviduct of the female; the yolk sac of the egg provides nutrients to the developing snake. Female snakes lay from two to over 50 leathery-shelled eggs per clutch, depending on the species. The process of laying eggs is called oviposition. Much of the egg development occurs within the female’s oviduct prior to oviposition. The ovary releases an ovulated egg via the ostium into the anterior area of the oviduct, called the infundibulum. Immediately, secretions from the oviduct coat the egg. Once the egg moves into the uterus, eggshell production begins via fibers secreted by uterine mucosal glands. The gestated egg moves out of the uterus and through the oviduct’s cloacal opening via rhythmic muscle contractions. Some pregnant snakes bask with their bellies facing up prior to laying eggs, possibly to warm their reproductive tracts. The mother snake lays eggs in succession as a cluster, and the eggs adhere to each other."

"Correct. Can you describe the male and female reproductive systems of a snake?"
"In males, the paired testes lie intracoloemically (within the coelom or common body cavity, as snakes, like most reptiles, have no diaphragm and so no separate thorax and abdomen; rather they have only a common coelomic cavity). They are situated cranial to each kidney, and caudal to the pancreatic tissue, with the right testis slightly cranial to the left, and are oval in shape. The testes enlarge during the breeding season, often reaching two to three times their quiescent state. Close to the testes lie the adrenal glands. Each testis has a solitary vas deferens leading down to the urodeum portion of the cloaca, where seminal fluids from the reproductive sexual segment of the kidneys are added.
"The male snake also has paired penises, known as hemipenes, in its tail. At rest they are like two inverted sacs either side of the midline and lie ventral to two other small invaginations in the tail which form the anal glands. When a hemipene’s lining becomes engorged with blood, it everts, forming a finger-like protrusion through the vent. As with the domestic cat, the hemipenes are often covered in spines and barbs, and they each have a dorsal groove into which the sperm drops from the cloaca, and so is guided into the female’s cloaca. The hemipenes therefore do not play any part in urination.
"The female has paired ovaries, cranial to the respective kidneys, with the right ovary cranial to the left. There are two coiled oviducts starting with the fimbriae opposite each ovary, and moving through the tubular portion of the infundibulum and on into the magnum. From here the tract merges into the isthmus and then the shell gland or uterus before opening into the muscular vagina. This organ ensures that the eggs are laid only when the timing is correct. The vagina empties into the urodeum section of the cloaca. The vascular supply is from the dorsally suspended oviduct mesentery, rather than the caudocranial route employed in mammals.
"Most females are stimulated to reproduce in the spring, when the weather warms and the daylight length increases. The tropical boas (such as the boa constrictor) and the Burmese python (Python molurus), however, start breeding when the temperature drops slightly during the cooler portion of the year.
"Some species of snake are oviparous (i.e., they lay eggs), others are viviparous (i.e., they bear live young). The latter are, for example, the garter snakes (Thamnophis sirtalis) and the boid family, which have a vestigial egg structure more closely resembling a placenta. Other species make nests, and some species of python, such as Slybella here, will incubate eggs by contracting and relaxing skeletal muscles, so creating warmth."
"Very good. Could someone, other than Henrietta, tell us how snakes mate?"
"I can." Caleb said. "Snakes find mates with a strong sense of smell. The males then court the female snake by slithering over her and trying to align their tails. Once they start mating, snakes can stay locked together for up to a day.
"All snake species have a specific time of the year that they mate. Snakes that live in areas with a winter will typically spend the cold months brumating. After brumation is over in the spring, the snakes are typically ready to mate.

Some species like garter snakes den together and mate once the weather warms enough to be active. Others either don’t brumate or spend their brumation alone.

In these cases, female snakes will produce pheromones. These signal to males that she is ready to mate.
"Snakes have a strong sense of smell that helps them locate other snakes. They have an organ known as the vomeronasal organ (also known as jacobson’s organ) that allows the snake to smell the pheromones. Snakes have a forked tongue that they use to pick up scent molecules. These are brought to the vomeronasal organs in the mouth.

The two tips of the tongue can catch the scent in two directions. The snake then uses any difference in the strength of the scent to locate a mate.
"Females produce pheromones to attract male snakes and tend to be willing to mate multiple males, but this can vary depending on the species. Some species of snake form a plug after mating.

This prevents the female from mating with other males. This means that any young produced will likely belong to the first male.

Female snakes can frequently store sperm as well. This means that a female can reproduce even if she did not find a mate that year.
"During courtship, a common strategy seen in many snakes involves the male rubbing his chin on the female. Others will use a specific type of tongue flick or vibrate to entice the female.

Pythons, like Slybella, and boas retain small vestigial limbs near the cloaca called spurs. Males typically have larger spurs than females. The male may use the spurs to try to stimulate the female and convince her to allow him to mate. He will try to align them and get his tail under hers. A female that isn’t ready to mate will normally flee or chase off any males. If she is, she will lift her tail, open her cloaca and allow the male to mate.
"Males have two copulatory organs known as hemipenes. Each of these organs is connected to a separate testicle.

The male uses his tail to align his cloaca with the female’s. Once he is in position, he inserts one of the hemipenes in the female’s cloaca to begin mating. Males will only use one hemipenis to mate. Since each hemipenis is attached to one testicle, this means a male can use the other hemipenis to mate again if he comes across another female before he has produced more sperm."
"Very good, Caleb."
"I wish I could see snakes fuck." said a mole. "You're about to. The reason I got Stantello here is so that Slybella can make and produce snake babies."
And, alas for poor Brain, he'd been leaning so much forward, getting photos of Slybella laying the eggs, that he fell fully through into the urodeum and down into the proctodeum. Thus, he had nowhere to go when what came next came. Stantello slithered over to Slybella and began to wrap himself around him. Two hemipenes poked out of Stantello's cloaca. Brian could do nothing as Stantello's hemipenis entered Slybella's cloaca and then exited, increasing speed. He took photos of the snake sex, though he knew all too well what would come at the end. And he was right. However, it was a long process of watching the hemipenis pushed in and out, as snake sex typically takes an hour, and can take an entire day. Eventually, the two reached climax.
As Brian took another shot with his camera, knowing they were close, the male ejaculated, and he got a photo of semen propelling up the hemipenis. SQUIRT! SQUIRT! SPLISHH! SPLISH! SPLOSH! A lot of went to her vagina, but some hit Brian. To his annoyance, once the snake had pulled his dick out, he soon pushed it in again, starting the copulation all over again. "How long do you think this will go on?" Brian asked.
"Well, if you had a pretty girl with you and nothing else to do all day, what would you do?" Dr. Bentenson asked. Brian sighed.
"This is going to be a LONNNNNNNNG day!"
And so it was. It wasn't until near the end of the last class when the snakes finally stopped fucking. Brian was now as coated in semen as he was urates and feces. He felt for sure that Slybella had to be pregnant from all of this copulating. He hoped that he'd be out soon. And he would get his wish.

Chapter 9: Excreted

It was not long before farts began to rush past Brian. He could see the cloaca open again, thankfully not for sex this time, but for his ticket out of there. As he was at the bottom, he was soon excreted, free at last. Well, almost. He had to wait as Slybella excreted the rest of her solid and semi-solid waste. SPLORT! SPLORT! SPLORT! Urates shot out of her cloaca, which bulged out, almost as it had when she had laid the eggs. PWICA! PWICA! PWICA! Soon after the urates crowned out, feces began to crown out. Brian waited as the Slybella voided the rest of her cloaca, which took about two minutes. And then, even after the last bit of waste had fallen from her cloaca, he was still stuck, as her mate's cloaca opened and excreted his wastes as well.

As soon as the two were distracted, making love again, and with their backs turned, he slowly crept to the edge of the cage, where he was let out. He took off the soiled suit, said "I fulfilled my part." and left the room as the bell rang. He washed off in the gym showers and headed home. He'd have enough of snakes for a while. Over the next few days, he took the test on all the material he'd taken notes on and aced it. Now he could graduate. He was glad when it finally reached Friday, for it was time to make love with his lover. The two were going to fuck as much as Slybella and her mate had.

Chapter 10: Aftermath

Brian made love with Leona, though, unlike Slybella, they used condoms. It was a fun night. As he pushed his penis into her and pulled it out of her, having the time of his life, the two listened to the news, hearing about a famous biology teacher who had, using an "anonymous and willing subject" found a way to send someone alive through a snake's digestive tract. "Wonder who'd volunteer to do something like that." Leona asked in between moans of ecstasy.
"Someone desperate, no doubt."
"Yep. And I get to graduate now."
"Wonder how you pulled it off. You seemed fucked up beyond all recall only a short time ago."
"It's because I was the volunteer."
"Wait, you were? You mean you made up that whole trip?"
"Yes. it had to be convincing. Didn't want anyone to find out, least of all my parents, for legal reasons."
"Well, if you've been through that snake, I suppose you've had a busy week."
"Yep. and that's why we're here tonight having the night of our lives." Brain said as the two continued to make love.