Using a Digestive Tract Diagram as a Study Guide
Creating Your Own Digestive Tract Diagram
Before your body can receive energy from food, it must first break it down into tiny bits for your body cells to absorb. This process is called digestion. Creating a digestive tract diagram not only helps you understand how your body breaks down the food you eat but also helps you remember the organs involved and the order in which digestion takes place.
What is the Digestive Tract?
The digestive tract - also known as the alimentary canal - is a series of hollow, muscular tubes food travels through that begins at your mouth and ends with your anus. It includes the pharynx, esophagus, stomach, small intestine, and large intestine. Some diagrams also include the liver, gall bladder, and pancreas. These accessory organs are included in the digestive system but aren’t part of the digestive tract. They help the digestive tract by providing hormones, enzymes and bile necessary for the complete breakdown of food. Before creating your own digestive tract diagram, let’s take a journey down the alimentary canal.
Digestive Tract Path
Suppose you are eating a peanut butter and jelly sandwich for lunch. Glands in your mouth secrete saliva that moistens your food during chewing turning it into a mushy mass. Saliva not only moistens your food but has enzymes in it to start breaking down starch, a carbohydrate found in bread. Your tongue pushes the food to the back of your throat or pharynx preparing it for swallowing. Because your esophagus lies directly behind your trachea (the tube that takes air into your lungs), a special flap of skin called the epiglottis flops over the opening of your trachea preventing any food or liquid from going into your lungs. Sometimes when you laugh or cough involuntarily when eating, your epiglottis makes a mistake and food or liquid goes into your airway. Lucky for us, this doesn’t happen too often! Once the food enters the esophagus it is called a bolus.
The muscles in the esophagus push and pull the bolus forward in a process called peristalsis. It only takes 2-3 seconds for the bolus to reach the J-shaped sac called the stomach where it is temporarily stored, then mixed and churned into a liquidy ooze called chyme. In the stomach, hydrochloric acid kills any ingested bacteria and helps produce the enzyme pepsin. Pepsin starts the breakdown of protein, a major nutrient found in peanut butter. The chyme slowly emptys from the stomach into the first part of your small intestine, the duodenum. The small intestine is a 1-2 inch diameter, 22 foot long tube coiled up inside your abdomen. With the help of hormones and enzymes from the pancreas, and bile from the liver, the small intestine’s job is to absorb all the nutrients from the chyme before sending them to the bloodstream. This process can take up to four hours because the nutrients are broken down further into carbohydrate molecules from the bread and jelly and protein and fat molecules from the peanut butter. Before the bloodstream carries these nutrients to body cells, they are filtered through the liver to remove toxins, bacteria and other things that may harm us.
Anything not absorbed by the small intestine continues down the alimentary canal and into the large intestine. Compared to the small intestine, the large intestine is bigger in diameter (about 3-4 inches) but much shorter - only five feet long. It ascends upward, transverses across and descends back down in a loop over the small intestine. The large intestine’s job is to compact the waste and absorb any leftover water and minerals from the chyme. As the waste moves through the last few inches of the large intestine (the rectum), it becomes a hardened brown mass which is voluntarily eliminated through the anus as feces.
Create Your Own Digestive Tract
There are several ways to study the digestive tract. You can print out a diagram (found at the end of this article), and label the organs. To help remember the order in which food travels and how digestion works, trace a pathway starting at the mouth and ending at the anus. As you pass each organ, describe that organ’s function. For example, for the stomach, say " this organ’s job is to temporarily store food and mix it into chyme." Once you are familiar with the pathway, draw your own digestive tract diagram using a dry erase board and markers. Include the liver, the gallbladder, and the pancreas in your drawing. When the bolus reaches the small intestine, remember to draw one path for where the nutrients go and another path for any chyme not absorbed by the small intestine.
Better yet, create your own digestive tract using objects from home to represent each organ in the alimentary canal. Use a small paper tube to represent the esophagus, a large plastic ziplock bag to represent the stomach, a long jumprope to represent the small intestine, and a longer paper tube roll to represent the large intestine. Take turns with a study buddy putting these items in order and explaining their function. To mimic the actions of the stomach, place a peanut butter and jelly sandwich into the plastic ziplock bag. Add 2 tablespoons of baking soda and 1/2 cup of vinegar to simulate hydrochloric acid. Seal the bag and squoosh the contents around with your fingers. Include the actions of the accessory organs (liver and pancreas) too. Fill spray bottles with water and spritz the small intestine to simulate the enzymes, hormones, and bile.
Digestive Tract Diagram
