Med-Surg - Gastrointestinal System, part 1: Introduction, Anatomy and Physiology Review

by Cathy Parkes November 20, 2021 Updated: August 09, 2023 5 min read

Full Transcript

Hi, this is Cathy with Level Up RN. This is the first video in our medical-surgical nursing gastrointestinal playlist. Throughout this playlist, I will be following along with our Level Up RN Medical-Surgical Nursing Flashcards. So if you have those, definitely pull those out so you can follow along with me. This playlist and the accompanying cards are designed to help you learn the most important facts and concepts you need to know to be successful on your nursing exams, on the NCLEX, as well as in nursing practice. If you have our cards, be sure to pay close attention to the bold red text on the cards because those are going to be particularly important points for you to know. At the end of this video and every video in this playlist, I'm going to be giving you guys a little quiz to test your knowledge of some of the key points that I will be covering in these videos. So definitely stay tuned until the end of the video so you can take that quiz.

During this video and the next video, I will be doing an anatomy and physiology review of the gastrointestinal system. So I'm a firm believer that fully understanding how a body system is supposed to work lets you think more critically about the signs and symptoms you would expect if something goes wrong with that body system. So I feel like this A&P review is an important part of the studying process.

The gastrointestinal system provides nutrients to support the body's functions through digestion, and it also allows for elimination of waste products through defecation.

There are three main components of the GI system.

One is the alimentary canal, so this includes the oral cavity, the pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anal canal.

Then we also have accessory organs, which include the salivary glands, the liver, the pancreas, and the gallbladder.

And then we have the peritoneum, which is the serous membrane that holds the digestive organs in place in the abdominal cavity of the body.

All right. Let's now go into a little more detail of each of the components of the alimentary canal. And this illustration can be found in our Medical-Surgical Nursing Flashcard deck.

So first of all, we have the oral cavity, which contains the buccal mucosa, lips, tongue, hard palate, soft palate, and teeth. You can also see the salivary glands here.

Functions of the oral cavity include mechanical and chemical digestion.

So we have mechanical digestion that is taking place, which is the grinding of food into smaller pieces through mastication.

And we also have chemical digestion, which is taking place. So digestion of carbohydrates will begin in the oral cavity through the action of salivary amylase, which is an enzyme. Then from the oral cavity, the food will move through the pharynx down the esophagus.

So the esophagus is a muscular tube that connects the pharynx to the stomach, and it contains two sphincters.

So we have this upper esophageal sphincter, which helps to protect against reflux of food into the airways and also prevents entry of air into the digestive tract.

And then we have this lower esophageal sphincter, which prevents reflux of gastric contents into the esophagus. So when we talk about GERD or gastroesophageal reflux disease, that disorder is associated with a weakened lower esophageal sphincter.

All right. So from the esophagus, the food will move into the stomach and the top part of the stomach here is the fundus, then we have the body and the pylorus here at the end.

So functions of the stomach include mechanical and chemical digestion. So there's a variety of cells here in the stomach that we've outlined on the flashcard, which include neck cells, G-cells, parietal cells, and chief cells.

So those cells will secrete mucus, gastrin, and hydrochloric acid. And basically, the food will be mixed with gastric secretions to form chyme, which which is spelled C-H-Y-M-E. And this chyme will empty into the small intestine.

All right. So the small intestine has three parts. From proximal to distal, we have the duodenum, the jejunum, and the ilium. So our little cool chicken hint here on the card is that DJ Ilium plays at the GI club. So if I ever become a DJ, I'm totally calling myself DJ Ilium, and you guys are all invited to my club.

All right. So in the small intestine, we have digestion that takes place as well as absorption.

And then we have peristalsis which moves the food from the stomach to the large intestine. A couple of other things I want to mention about the small intestine.

Inactivated pancreatic enzymes will enter the duodenum and become activated and help to digest carbohydrates, fats, and protein. We also have bile that enters the duodenum and that helps to emulsify fat.

All right, then the food moves to the large intestine. So structures in the large intestine include the cecum, the ascending colon, the transverse colon, the descending colon, the sigmoid colon, and the rectum and anal canal.

So feces will move through the colon through segmental contractions. In the colon, we have the absorption of water and electrolytes. So if a patient has to have their colon removed, we're not going to have that absorption of water and they are going to have very liquid stool.

And then defecation is controlled by both internal and external anal sphincters.

All right. You guys ready for your first quiz of the gastrointestinal system? I have three questions for you. First question, what do you call the serous membrane that holds digestive organs in place within the abdominal cavity? The answer is the peritoneum. Question number two, where does digestion of carbohydrates first take place? The answer is in the oral cavity from the action of salivary amylase. Question number three, name the three components of the small intestine from proximal to distal. The answer is duodenum, jejunum, and ilium.

All right. I hope you found this video to be super helpful. If so, be sure to like the video. Leave me a comment. Take care and good luck with studying.

Hi, I'm Cathy with Level Up RN. This is the first video in our medical-- [inaudible]. Hi, this is Cathy with Level Up RN. This is the first video in our medical-- oh my God. Hi, this is Cathy with Level Up RN. This is the first video in our medical-surgical nursing gastrointestinal playlist. I will be following-- okay, just forget it.

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