Just in case you wanted to know what was going on during the swallowing of that In-and-Out cheeseburger, or in my case: peanut butter and honey sandwiches. Man... I've had so many of those the past few days. Not to mention dropping the glass bottle containing honey and frantically trying to clean it up before the ambush of ants comes along. A stabbing pain in my foot this morning reminded me that I didn't sweep well enough; it was just a small piece of glass though. Mom and auntie Alma, I'm starting to miss home cooking, it's not quite the same when I do it.
One of the benefits of being on the curriculum track is that I have more time to integrate material and create study products such as this. The quality on my iphone is fairly poor, so here's a link to view the image on google drive, which allows more zooming in and out: GI overview My upcoming exam this Tuesday is on the gastrointestinal tract. It is very scattered, but mildly so compared to my usual diagrams, some of my study products look more like a game of connect the dots. Here's some of the details that I omitted.
Mouth:
The hard palate, gingiva, and dorsal tongue have prekeratinized or keratinized epithelium, as keratin helps provide the tougher structure as opposed to the thinner and more permeable non-keratinized epithelium found on all surfaces of the mouth. This is why drugs are more quickly absorbed under the tongue.
The lips are red because the blood vessels are very close to the epithelium, separated by a thin vermilion zone. Stress can contribute to a lack or excess of filiform papillae contributing to white stripes on the tongue or a hairy tongue respectively.
Salivary amylase clean the teeth by dissolving starchy foods stuck between the teeth. Bacteria contain an enzyme called levansucralse which breaks down sucrose to glucose and fructose. the glucose is used for bacterial glycolysis and acid production and the fructose forms the bacterial biofilm (plaque) on the teeth.
Esophagus:
The upper esophageal sphincter relaxes immediately after swallowing to allow the food to pass then increase to a pressure above resting pressure to push the bolus (ball of food) down. The contractions continue until the lower esophageal sphincter (LES) relaxes to allow food into the stomach then returns to resting pressure. Achalasia is a failure of the LES to relax leading to difficulty in swallowing, regurgitation, and/or chest pain. A technique called manometry is used to determine the pressure within the esophagus.
Stomach:
High acidic leading to activation of digestive zymogens (inactive forms of enzymes). The endocrine hormone Ghrelin controls the hunger sensation as is increased when the stomach is empty. Various weight-loss drugs target this hormone to decrease the hunger sensation. Ghrellin is also reduced in gastric bypass patients, which presumably contributes to success in various treatments. I am speculating that one problem would be the lack of nutrients that those with a non well-balance diet would receive. People can feel hungry even after eating much junk food because of the lack of nutrients the body is receiving, and the Cheetos puffs and Dr. Pepper lack the nutrients that our body craves, thus leaving us hungry despite finishing the whole bag. The reduction of ghrellin may decrease the indication a lack of essential nutrients, leading to a false sense of meal satisfaction.
The protective mucus of the stomach gives protection against the acidic environment. However, when this mucus layer is broken down, typically by Helicobacter Pylori, it leads to a peptic ulcer. This ulcer production can be promoted by drugs such as Ibuprofen. Peptic ulcers can be treated by drugs known as proton pump inhibitors Omeprazole and Esomeprazole and H2-Receptor antagonists [Ranitidine (Zantac), Cimetidine (Tagamet), and Famotidine (Pepcid].
Liver:
The gatekeeper. The portal vein carries blood from all of the organs to the liver for detoxification and metabolism. It contains super-cells called hepatocytes which are rich in mitochondria, smooth ER for detoxification, rough ER (protein synthesis), and golgi.
Pancreas:
The pancreas is a big storehouse for digestive enzymes. It contains zymogens which remain inactivated until it reaches the duodenum, where the slightly lower pH activates it. During acute pancreatis, which can be caused by alcoholism, the zymogens become activated in the pancreas, causing it to degrade. The pancreas makes bicarbonate, which acts as an acidic buffer, but it lacks the protective mucus of the stomach.
Small Intestine:
The bulk of food digestion occurs in the small intestine. It contains a brush border which aids in absorption of nutrients and increases the surface area.
Large Intestine:
Responsible for the reabsorption of water and inorganic ions. Normal flora (healthy bacteria) thrive in the small intestine and assist in breaking down nutrients that we lack the enzymes to do so. The breakdown of these enzymes usually leads to sulfur production, causing that familiar odor that you try to deny... One time, many years ago, my sister farted on an elevator full of people at Magic Mountain and my dad kept going on, making jokes about how terrible it smelt. He was unaware who passed gas. Soon after, my sister's eyes started to water and she smacked my dad on the arm in a fit of embarrassment as we exited the elevator; her normal flora produced a not so floral smelling odor.
Rectum:
Here's the quickest way to get drunk: The rectum contains a relatively superficial venous plexus that allows for quick absorption into the bloodstream and entry into the digestive system without first going through the liver. Therefore, some engage in the process of butt chugging this has very dangerous consequences, as the effects of alcohol are magnified.
This venous plexus is also a common cause of hemorrhoids, caused by increased venous pressure due to straining or other effects.
A very nice overview! Just one thing… its "GI tract"… not track. :)
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