What happens to the digested food? How does my digestive system work? Bacteria in your GI tract, also called gut flora or microbiome, help with digestion. This lesson will explain what nausea, vomiting, and regurgitation are. The food we eat needs to be broken down into small pieces which we chew up into even smaller ones before swallowing them. Though students know they must eat to live, they may not have made the distinct connections between food and the body properly repairing itself, or food and growth; even a connection as simple as a lack of iron or carbohydrates making one tired.
What is the digestive system?
The walls of the small intestine absorb water and the digested nutrients into your bloodstream. As peristalsis continues, the waste products of the digestive process move into the large intestine. Waste products from the digestive process include undigested parts of food, fluid, and older cells from the lining of your GI tract. The large intestine absorbs water and changes the waste from liquid into stool.
Peristalsis helps move the stool into your rectum. The lower end of your large intestine, the rectum, stores stool until it pushes stool out of your anus during a bowel movement.
Watch this video to see how food moves through your GI tract. As food moves through your GI tract, your digestive organs break the food into smaller parts using:. The digestive process starts in your mouth when you chew. Your salivary glands make saliva , a digestive juice, which moistens food so it moves more easily through your esophagus into your stomach.
Saliva also has an enzyme that begins to break down starches in your food. After you swallow, peristalsis pushes the food down your esophagus into your stomach.
Glands in your stomach lining make stomach acid and enzymes that break down food. Muscles of your stomach mix the food with these digestive juices. Your pancreas makes a digestive juice that has enzymes that break down carbohydrates, fats, and proteins.
The pancreas delivers the digestive juice to the small intestine through small tubes called ducts. Your liver makes a digestive juice called bile that helps digest fats and some vitamins. Bile ducts carry bile from your liver to your gallbladder for storage, or to the small intestine for use. Your gallbladder stores bile between meals. When you eat, your gallbladder squeezes bile through the bile ducts into your small intestine.
Your small intestine makes digestive juice, which mixes with bile and pancreatic juice to complete the breakdown of proteins, carbohydrates, and fats. Bacteria in your small intestine make some of the enzymes you need to digest carbohydrates. Your small intestine moves water from your bloodstream into your GI tract to help break down food. Your small intestine also absorbs water with other nutrients. In your large intestine, more water moves from your GI tract into your bloodstream.
Bacteria in your large intestine help break down remaining nutrients and make vitamin K. Waste products of digestion, including parts of food that are still too large, become stool.
The small intestine absorbs most of the nutrients in your food, and your circulatory system passes them on to other parts of your body to store or use. Special cells help absorbed nutrients cross the intestinal lining into your bloodstream. Your blood carries simple sugars, amino acids, glycerol, and some vitamins and salts to the liver.
Your liver stores, processes, and delivers nutrients to the rest of your body when needed. The lymph system , a network of vessels that carry white blood cells and a fluid called lymph throughout your body to fight infection, absorbs fatty acids and vitamins. Your body uses sugars, amino acids, fatty acids, and glycerol to build substances you need for energy, growth, and cell repair.
Your hormones and nerves work together to help control the digestive process. Signals flow within your GI tract and back and forth from your GI tract to your brain. Cells lining your stomach and small intestine make and release hormones that control how your digestive system works.
These hormones tell your body when to make digestive juices and send signals to your brain that you are hungry or full. Your pancreas also makes hormones that are important to digestion. You have nerves that connect your central nervous system—your brain and spinal cord—to your digestive system and control some digestive functions. For example, when you see or smell food, your brain sends a signal that causes your salivary glands to "make your mouth water" to prepare you to eat.
When food stretches the walls of your GI tract, the nerves of your ENS release many different substances that speed up or delay the movement of food and the production of digestive juices. The nerves send signals to control the actions of your gut muscles to contract and relax to push food through your intestines.
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The digestive system Bacteria in your GI tract, also called gut flora or microbiome, help with digestion. Why is digestion important? One important thing they should start to understand is that in order for their "systems" to properly function, they need energy and materials from food as the benchmark states.
Though students know they must eat to live, they may not have made the distinct connections between food and the body properly repairing itself, or food and growth; even a connection as simple as a lack of iron or carbohydrates making one tired.
This lesson will focus on the digestive system in order to address the latter part of the benchmark—that undigested food is eliminated. In addition, it will begin to explore where nutrients come from and their importance for particular tasks in the body.
This Science NetLinks lesson is the first of a three part series. It works in conjunction with Nutrition 2: Good Food, Good Health, a lesson that teaches about the food groups and how vitamins and minerals help the body function properly, and Nutrition 3: Younger elementary school students might think that the contents of the body is what they have seen being put into it or coming out of it.
Students know food is related to growing and being strong and healthy, but they are not aware of the physiological mechanisms. In upper elementary, students can list a large number of organs and by 5th grade, "students know that food undergoes a process of transformation in the body. Students should naturally begin talking about the digestive system in response to the final question listed above. Let them know that food and the digestive system are the topics for this lesson.
Once students have done some preliminary exploration of the digestive system, ask these questions:. Next, brainstorm answers to these questions. There are many answers, many of which are not very obvious, but this will get students thinking beyond the basic processes of the digestive system.
Depending on your students' ability, this article can be read online or printed out and read in class. Also, it is not necessary to click on the links within the text for this lesson.
Provide students with the Digestive System student sheet. They should get into groups and cut out parts of the digestive system from colored construction paper as they make their way through the article.
On each organ, students can write a one- to two-sentence description of the organ's purpose. In the end, they will have a recreated digestive system of their own.