Cell Organization in the Human Body
The human body is complex! In this lesson, it is broken down into smaller, manageable parts. Students will build a lung model and discover how different parts of the respiratory system work together to make breathing possible. Next, they will discuss how this system works together with other systems in the body so oxygen can reach every cell of the body. While students perform these explorations, they will realize that multicellular organisms consist of systems, which are a collection of organs and tissues, and all of these are made of cells.
Remote Learning: This lesson plan can be adapted to work remotely. The Engage section of the lesson can be done over a video call. Then, students can make the model individually and independently using the Make a More Advanced Lung Model video as a guide. Allow the students to make a model with only one lung instead of two as joining two straws can be tricky. A set of materials can be prepared in advance, or, if students gather the materials themselves, ask for adult supervision while cutting the hard plastic bottle. Students can use the Student Worksheet to complete their exploration independently and can then share their observations and thoughts with each other, virtually. You can also use the Simple Lung Model video to help students understand the breathing mechanism shown in the model. End the lesson with a discussion over a video call during the Reflect section.
- Understand the different levels of organization (cell, tissue, organ, system) in an organism.
- List examples of cells being organized into tissues, organs, and systems in the human body (e.g. lung cell, lung tissue, the lung, respiratory system).
- Understand how the human respiratory system works, and how it interacts with the human circulatory system.
NGSS AlignmentThis lesson helps students prepare for these Next Generation Science Standards Performance Expectations:
- MS-LS1-3. Use argument supported by evidence for how the body is a system of interacting subsystems composed of groups of cells.
|Science & Engineering Practices||Disciplinary Core Ideas||Crosscutting Concepts|
|Science & Engineering Practices||Engaging in Argument from Evidence.
Use an oral and written argument supported by evidence to support or refute an explanation or a model for a phenomenon.
Developing and Using Models. Develop and/or use a model to predict and/or describe phenomena.
Develop a model to describe unobservable mechanisms.
|Disciplinary Core Ideas||LS1.A: Structure and Function.
In multicellular organisms, the body is a system of multiple interacting subsystems. These subsystems are groups of cells that work together to form tissues and organs that are specialized for particular body functions.
||Crosscutting Concepts||Systems and System Models.
Systems may interact with other systems; they may have sub-systems and be a part of larger complex systems.
A system can be described in terms of its components and their interactions.
Structure and Function. Complex and microscopic structures and systems can be visualized, modeled, and used to describe how their function depends on the shapes, composition, and relationships among its parts, therefore complex natural structures/systems can be analyzed to determine how they function.
Per group of 2–4 students:
- Disposable, empty transparent bottle (10–16 fluid oz) with lid, made of hard plastic (such as a sports drink bottle)
- Three balloons (8-inch or 6-inch balloons work well)
- Paper or plastic drinking straw
Teacher or another adult:
- Utility knife
- A few extra balloons in case one pops
- A few extra straws
Background Information for TeachersThis section contains a quick review for teachers of the science and concepts covered in this lesson.
All living organisms consist of cells, but most multicellular organisms are not simply a group of cells. Several organizational structures can be found within these organisms. In increasing level of complexity, cells are grouped into tissues, organs, and systems before reaching the level of the organism. This lesson will use the human body to explain this organization.
Organs and other parts of the body that work together to perform a major function in a living organism are called systems. We can identify ten systems in the human body, each with its own distinct task: the circulatory or cardiovascular system pumps blood through the body, the respiratory system allows the exchange of gases, the digestive system breaks down food for energy production, the endocrine system controls the hormones in our bodies, the reproductive system allows reproduction, the muscular system helps with the movement of the body, the nervous system controls the senses, the urinary system allows the removal of waste, the skeletal system gives the body its structural support, and the integumentary system creates protection through the skin, hair, and nails. Each of these systems consists of several parts. The respiratory system, for example, consists of the nose with the sinuses and nasal cavity, the pharynx, the larynx or voice box, the trachea or windpipe, the bronchi and bronchia, the lungs with the alveoli, the pulmonary capillaries, and the diaphragm (Figure 1). Note that the mouth and some muscles other than the diaphragm also aid breathing, but are listed under the digestive system and the muscular system, respectively. Each part of the respiratory system fulfills a specific task, and it is made of tissue that helps fulfill this task. The diaphragm is a muscle and made of muscle cells that together form muscle tissue; similarly, the lungs are made up of lung cells and make up lung tissue, and the windpipe is made of cartilage, yet another type of tissue. Yet, all these parts work together to support breathing.
Figure 1. Visualization of the respiratory system with all its parts.
Each system also needs the help of other systems to fulfill its task inside the body. The respiratory system does not work in solitude, it relies on the circulatory system to transport oxygen to the cells and to transport carbon dioxide back to the lungs.
Because the human body is a complex multilevel organization, minor deviations can have seemingly unrelated consequences. In this lesson, students will explore this by looking into iron deficiency anemia. Iron is needed to create hemoglobin, the oxygen-carrying protein that give red blood cells their red color. Insufficient iron leads to insufficient hemoglobin and an inadequate way of delivering oxygen to the cells around the body. It can show as fatigue, or even shortness of breath.
In this lesson, students will create a model of the respiratory system to discover how it works. This allows students to see how tissues are groups of similar cells that are specialized in a particular function, and how organs are groups of specialized tissues that are gathered in a particular area in the body and perform a specific function. Students will see how the respiratory system works, and how it needs the help of other systems. In addition, students will learn how, on a cellular or even molecular level, oxygen is carried around in the body. With all this information, students can finally start to comprehend why iron-deficient anemic patients may suffer from shortness of breath.
As students dive into a particular system and zoom out to see how the systems work together, they will hopefully gain some respect for the complexity, beauty, and efficiency of their bodies.