Anatomy Travel Bureau welcomes you to Your Digestive System! [pic] Kaitlynn Daseke-Collette Anatomy and Physiology The Digestive System This journey your about to experience may take up to several days. I hope you’ve packed well. We will be going through seas, acid rains, and dry, desert like conditions. So without wasting any more time let me give you a play by play of your vacation! First Stop Our first stop will be breakfast after you wake up on day one. You will be able to eat what ever your heart desires. Anything from a stack of pancakes to something completely unrelated to “breakfast”, like pizza.
Choose wisely, you will be stuck with your breakfast for the rest of the tour! [pic] This is where I hand it over to your breakfast! Enjoy your trip! [pic] Hello there! I’m that stack of banana pancakes you devoured at breakfast this morning. Our real first stop on this journey through your digestive system is the mouth. The mouth is a pretty obvious place on the body. So when you put me in your mouth this morning I met up with some saliva and then I was chewed also known as masticated. Your cheeks and lips hold your food in your mouth while your teeth take care of the “masticating”.
The tongue is what helps mix food and saliva together and it also initiates swallowing. The process of digestion has already begun believe it or not. This is the first step in breaking food down. Although this may sound a little gross it’s not just about breaking down food for digestion, we have tiny buds on our tongue which I’m sure you all know as TASTE BUDS! Taste buds are the “taste receptors” allowing you to taste the butter, banana, syrup and what ever else you put on me this morning before we began this journey!
Before we get any further and you are unable to hear me let’s just go through all the technical stuff so we can actually enjoy the sites! Our second stop on this fascinating trip will be the Pharynx. Two passageways that are most commonly taken are the oropharynx and laryngopharynx. There is also the nasopharynx. Which when your body was under development we agreed to divide and it now currently belongs to the respiratory system, it’s kind of like their own private door. But not to worry, you’re not missing much! First we will go through the oropharynx which leads to the laryngopharynx which will lead us to the esophagus.
You might feel a little bit of a squish here and there from the muscle layers of the pharynx walls. They contract to help propel us to the esophagus, this is also called peristalsis. The Esophagus This is also known as the gullet. It runs most hours of the day from the pharynx through the diaphragm to the stomach (it’s about 10 inches/25 cm long). Before we get any further I should probably let you in on this one thing. The walls of the alimentary canal organs (esophagus to large intestine) are made up of basically the same types of tissue layers. The first would be mucosa, it’s the innermost layer. It’s a moist membrane that lines the cavity (lumen). Mucosa has surface epithelium, a small amount of connective tissue and a bit of smooth muscle. • Second we have submucosa which as you might be able to guess is found beneath the mucosa. It’s basically a connective tissue that contains blood vessels, nerve endings, lymphnodules and lymphatic vessels. • There’s a muscle layer made up of an inner, circular layer and an outer longitudinal layer of basically just smooth muscle cells, this is called the muscularis externa. Serosa is the outermost layer of the wall. This is a single layer of flat serous fluid that produces cells. Visceral Peritoneum makes slippery parietal peritoneum. Parietal peritoneum lines the abdominopelvic cavity by mesentery (way of a membrane extension). The walls also contain important “intrinsic nerve plexus”, I know your thinking you don’t know what that is, to be honest neither am I. But I think it might be kind of important to know that there is two, the submucosal nerve and the myentreric nerve plexus. They’re actually a part of the autonomic nervous system.
There just there to regulate the mobility and secretory activity of GI (Gastrointestinal) tract organs. [pic] Alright, third stop. The stomach. It is located on the left side of the abdominal cavity. Here we will be hidden by the liver and diaphragm. There are a few places around the stomach you might want to stop and see. The first is the cardiac region, as you might guess it was named this due to its position near the heart. It surrounds the cardioesophageal sphincter which is where we will have entered the stomach. The fundus is the expanded part, very roomy, you should probably stretch your legs here, move around.
It’s lateral to the cardiac region. The body then is the midportion and as it narrows it turns into the pyloric antrum. Then of course the funnel shaped pylorus which is the part that is continuous with the small intestine. Interesting Facts about the Stomach • Approx. 10 inches • Diameter depends on how much food its holding • A full stomach can hold about 4 liters/1 gallon of food From the stomach we will enter the small intestine through the pyloric sphincter. This is the major digestive organ. It prepares usable food for the journey into the cells of the body.
The small intestine is anywhere from 8 to 18 feet long in a living person. It’s kind of a tube made of muscle and it just extends from where we entered to the ileocecal valve. At the small intestine there are three places I recommend taking a peak at. • Duodenum means “12 finger widths long”. • Jejunum (“empty”) • Ileum (“twisted intestine”) – this also joins the large intestine at the ileocecal valve. Most of your food digestion occurs in the small intestine and it is more than qualified to do so. The walls of the small intestine have three structures that help tremendously with absorption.
These three are the microvilli, villi, and circular folds. The microvilli are tiny projections of the plasma membrane of the mucosa cells that make the cell surface look fuzzy. The villi are fingerlike projections; they have a velvety appearance and also feel soft. This is where a lot of the absorption occurs. There are also circular folds that are deep folds of mucosa and submucosa layers. ?Villi Believe it or not by the time you are done looking around these three sites and seeing the microvilli, villi and circular folds we will be on our way already through the ileocecal valve to the large intestine.
So grab your stuff and let us go take a look see. The Large Intestine Though it’s larger in diameter it is shorter than the small intestine. The large intestine runs about 5 feet long. These 5 feet are from the ileocecal valve to the anus. The main function of the large intestine is to dry out the food residue that cannot be digested. It does this by absorbing water and eventually eliminates the residues from the body as feces. The large intestine is divided into 5 subdivisions. They are: 1. The Cecum, its saclike and the first part of the large intestine. 2.
The Appendix, which hangs from the cecum, it’s very wormlike and sometimes because of its shape it can cause issues like appendicitis. This happens when the appendix becomes inflamed. 3. The colon which has several regions that takes you through the pelvis. 4. The rectum lies in the pelvis between the sigmoid colon and anus. 5. The anus, this is the part where feces exit the body. The anus is where our journey together will end. I hope you enjoy this journey through out the digestive system and come back to visit again real soon! [pic] Without any further explanation, please follow me through the pharynx…