Human Body Systems - Parasites Grade Range: Middle School Key Terms Lesson Time: 40 minutes Materials and Resources Circulatory system Digestive system Immune system Malaria Nervous system Parasite Plasmodium Tapeworm Trypanosomiasis Regional map Videos and/or images of parasites zview Activity Overview Parasites are everywhere! Parasites are some of the most abundant organisms on earth and are found in the air, in the soil, in our food and water, and even in our bodies. Students will learn about four common parasites mosquitoes, Plasmodium, Trypanosoma brucei, and tapeworms and how they affect the body. By exploring different parasites and their effects, students will gain a better understanding of the body s organ systems and how they connect. Essential Questions 1. How are structures and functions related in the human body? 2. What systems can be observed in the human body? 3. How are human body systems interrelated? Objectives Investigate the effects of different parasites on the human body Describe how different human body systems are connected Introduction Prior to beginning this activity, students should have background knowledge of human body systems and how they are all connected. They should also have a basic understanding of somatic cells and their structures. Introduce the activity by reviewing how all of the human body systems are connected and rely on each other to function. Explain that when one system is affected, the whole body can be affected. Ask the students, Have you or any of your pets ever been bothered by a mosquito or a tick? If you have pets, do they take heartworm medication? Explain that mosquitoes, ticks, and heartworms are three common examples of parasites. Show students videos and/or images of different parasites and ask students how they think parasites such as the hookworm, Guinea worm, human bot-fly, screwworm fly, and roundworm affect different systems of the human body. Display a regional map and discuss the parasites that live around the school and local neighborhoods. Discuss safety and hygienic precautions that should be taken to avoid these parasites. Inform students that they will review human body systems by learning more about parasites and how they travel through the body. 2017 zspace, Inc. All Rights Reserved Human Body Systems - Parasites 1
Teacher Note: Evaluate student sensitivity when discussing local parasites. Consider focusing the discussion on prevention as opposed to the potential for transmission, if appropriate. zspace Activity Activity Questions Provided in Studio Answers may vary. Sample answers are provided below. 1. Parasites are small organisms that survive by taking nutrients from their host s body. In the process, parasites harm their host, which can sometimes even lead to death. Human parasites must first get onto or into the human body. The human body has many ways to keep out intruders. However, where are some places on the body where parasites can enter? How could a parasite enter the body? Parasites can enter the body through any membrane. Common ways parasites enter the body include: bare skin that touches soil, ingestion of contaminated food or water, and insect bites. 2. Although they can be pesky parasites, mosquitoes can be fascinating creatures! Did you know that only males make a buzzing sound? Females fly silently! 3. Have you ever been bitten by a mosquito? If so, the culprit was a female mosquito! Females bite humans to get nutrients from human blood for egg production. Male mosquitoes do not bite humans! Mosquitos bite by using their tubelike mouth structure called a proboscis, which can pierce human skin. Use the Ruler tool to measure the length of the proboscis. How long is the proboscis of a mosquito? The mosquito proboscis is approximately 5 mm long. 4. Malaria is a disease that is caused by a parasite called Plasmodium. Plasmodium, and therefore malaria, is transmitted by mosquito bites. It is important to know that not all mosquitoes carry Plasmodium. Malaria due to mosquito bites is most common in warm climates near the equator. When the mosquito bites the skin, it allows the parasite to enter the body. Examine and dissect the Plasmodium cell. How is the Plasmodium cell similar to a human cell? How is it different? The Plasmodium has a nucleus and mitochondria like a human cell. It has a different shape and organelles that human cells do not have, such as an apicoplast. 5. A mosquito carrying Plasmodium bites a human on the arm with its proboscis. Which body system does the Plasmodium enter? The Plasmodium enters the circulatory system and moves around the body. 6. Once the Plasmodium is in the bloodstream it travels from the arm to the liver. Follow the Plasmodium s path from the arm along the circulatory system to the liver. Once it reaches the liver, what body system is then affected? The digestive system. Once the Plasmodium is in the digestive system it could reach many vital organs such as the heart. It could travel in through the inferior vena cava back to the heart then be pumped out through the cardiac arteries that supply blood to the heart. 7. After a period of a few weeks maturing in the liver, the Plasmodium reenters the bloodstream and infects red blood cells. Within the cells it begins to reproduce and multiply. The infected red blood cells eventually burst and more Plasmodium organisms enter blood to restart this species life cycle. Once the Plasmodium is in the bloodstream it can cause big problems! What important organs could it reach through the circulatory system? Describe an organ that is at risk and how the Plasmodium could reach that organ from the circulatory system. Once in the bloodstream, plasmodium can reach any vital organ. It could reach the brain because veins and capillaries supply oxygen-rich blood to the brain to keep it working properly. 2017 zspace, Inc. All Rights Reserved Human Body Systems - Parasites 2
8. Sometimes the structure of a red blood cell changes when it is infected by Plasmodium. This change causes the infected red blood cell to become stiff and form blockages in arteries. Think about how the circulatory system functions and how it connects with other systems. What kinds of problems could happen if an artery becomes blocked by Plasmodium -infected cells? How would other organ systems be affected? If arteries that supplied blood to the brain became blocked the brain could not get oxygen and this could cause a stroke. 9. African trypanosomiasis, also known as sleeping sickness, is a disease caused by a parasite called Trypanosoma brucei. This parasite is transmitted to humans by the tsetse fly. After you are bitten by the fly, the parasite multiplies in the tissue under your skin and inside the lymph nodes in your neck. Think about how the Plasmodium traveled around in the body. How does this parasite get from a bite on your leg to nodes in your neck? The parasite would enter your circulatory system and travel through your veins to your heart. It would then be pumped back into arteries leading to your lymph nodes. 10. After weeks or sometimes years, the trypanosomiasis parasite crosses into the brain. The brain has a special protective membrane that separates the blood from brain fluid called the blood-brain barrier. Use the Cutting Plane to observe the edges of the brain and where it borders the rest of the body. What part of the nervous system is affected once the parasite crosses this barrier? What types of problems do you think this could cause? Once the parasite crosses the blood-brain barrier it has infected the central nervous system. Symptoms of this parasite include changes of behaviour, confusion, sensory disturbances, poor coordination, and disturbances in sleep. 11. Both the Plasmodium and the trypanosomiases parasites entered the body when an insect bit the human. There are other ways that a parasite can enter the body. Someone could accidentally ingest a parasite. Often parasites are found in undercooked meat or infected water. A tapeworm is found in undercooked meat. Often, people do not even know they have a tapeworm until they show symptoms weeks later. Symptoms can include abdominal pain, vomiting, and weight loss. Trace the path of a tapeworm in the digestive system from ingestion to excretion. What organs does it pass through? The tapeworm passes through the mouth, esophagus, stomach, small intestine, large intestine, and rectum. 12. Use the Cutting Plane tool to view the inside of the small intestines. This is where the tapeworm eggs hatch into larvae! Use the Cutting Plane tool to look at the insides of the small intestine. The worms latch on the intestinal walls and begin to grow. Why do you think the small intestine is a good home for a parasite like the tapeworm? The small intestine is the primary area in which the body absorbs nutrients from food. This is an ideal place for a parasite like a tapeworm to live because it can feed in the nutrient-rich environment and has room to grow. 13. Most things are passed on from the small intestine to the large intestine and then out of the body. However, the tapeworm stays in your small intestine. What structures allow the tapeworm to attach to your small intestine? The tapeworm uses both the suckers and the hooks on the rostellum. 14. A pork tapeworm can grow as long as six meters. Use the Ruler to get an idea of how long six meters is in comparison to your body. 15. From the intestines, tapeworms may migrate to the muscles or eyes. They can also infest the brain, where they can cause seizures, headaches, and potentially fatal brain swelling. How would a tapeworm get from your intestines to your brain or your eye? The tapeworm could pass through the membrane in the intestines into a capillary that supplies blood to the organ. Once it is in the circulatory system, it can travel back to your heart and into your brain or eye. 2017 zspace, Inc. All Rights Reserved Human Body Systems - Parasites 3
16. Now, create your own parasite! Use models from the Model Gallery in your Backpack. Label these models with Notes to help visually explain how your parasite works. Take a photo when you are done. Photo. Closing Questions for Discussion 1. What actions can be taken to reduce the risk of parasites? Often, access to clean water and food safety measures are highly effective in reducing the number of parasite-related diseases. 2. Which parasites are the most dangerous? Why? Correct Answer: Typically parasites that affect the nervous system are the most dangerous. This is because problems originating in the brain and other parts of the central nervous system can include seizures, strokes, infection, and death. 3. How do parasites take advantage of your body s connected systems? Your digestive system can be affected by a tapeworm when it lays eggs in your stomach or absorbs nutrients in your intestines. Your nervous system can be affected by a tapeworm if it migrates to the brain or sensory organs because it can cause swelling and seizures. Your circulatory system can be disrupted as tapeworms move throughout the body in blood vessels. All of these systems are interconnected, so a parasite can travel between them. 4. How do your body systems work together to fight invaders such as parasites? Correct Answer: Your defensive cells that are part of your immune system are created in your bones, which are part of your skeletal system. These cells attack invaders such as parasites and travel around the circulatory system to the site of the problem. 5. Name three different body systems and describe how they might be affected by a tapeworm in your body. The digestive system, the nervous system, and the muscular system can be affected by tapeworms. Extension Activity: Research other types of parasites and how they affect your body. Extension Activity: Research the areas of the world most affected by malaria, including the geographical location, the possible reasons for the epidemic, prevention methods, and the adverse effects of the disease. Extension Activity: Research potential benefits of various parasites. Extension Activity: Work in a group. Imagine that your group is a team dispatched by the mayor to help deal with local parasite problems. Research a common parasite and how it affects body systems, and prepare recommendations for improving the parasite problem. (Each group should select a different parasite to research.) Follow-up Activity: Use your knowledge of parasites and how they affect body systems. Write a first-person narrative to describe how the parasite you created enters and exits the body, where it lives and reproduces, what organs and organ systems are affected, how it travels around the body, and what symptoms it causes. Follow-up Activity: Tapeworm model - VIVED Science Follow-up Activity: Symbiotic Relationship s - Studio Teacher Note: This activity can also be used as an introduction to the Human Body Systems - Parasites activity. 2017 zspace, Inc. All Rights Reserved Human Body Systems - Parasites 4
Differentiation Group students heterogeneously to allow students with a strong command of the English language to assist in reading or interpreting questions Provide a handout with a list of vocabulary terms and definitions that will appear in the activity Allow students to provide answers that are handwritten, typed, or verbal Give students a variety of presentation styles to choose from (using charts/graphs, PowerPoint, making 3D presentations, creating videos/movies, making posters) Have students work as partners or in small groups (younger children could partner with older buddies) Use text-to-speech if needed Enrichment: Students could find real-world problems involving the concept and design solutions to those problems Enrichment: Students could work on the discussion questions and lead the class discussion Enrichment: Students could research similar topics and create presentations 2017 zspace, Inc. All Rights Reserved Human Body Systems - Parasites 5