Organs and Artificial Organs

Teaching Strategies

This section presents one approach to teaching middle grade learners the information on cardiovascular physiology that has just been presented. The information should be presented in a two week unit for a class that meets daily or a three week unit for classes that meet on a block schedule every other day. Depending on the level of learners in the class the information can be expanded to by using the information in the resources found in the bibliography section of this paper.

Getting Started

This unit is designed to enhance and enrich the education already taking place in a general life science class. The information contained is for furthering background information to an instructor in the classroom that has limited resources based on the limits of textbooks for the middle school age children.

The instruction is to be focused on tying everything together about cells, tissue, organs, and organ systems in order to create a better framework of concepts for students. Instruction of the cell should be as complete as possible prior to teaching this unit: including the structures of different cells, the organelles and their functions, and the mechanisms for transport materials into and out of the cell. Students should also have a foundation of specialized cell structures for use in different tissues in order to make up different organs. Once students have achieved mastery on this they are ready to delve deeper into one organ system, this being the cardiovascular system.

The framework for explaining and enriching students should follow same flow as the background information of this paper. Students should then be introduced to the parts of the cardiovascular system focusing on the structure and function of the heart, what blood pressure is, and the vast vascular network the blood flows through. This concludes with a section on cellular respiration as it ties all the information learned back to the functions of the cell and develops in students the relationship between cells, tissue, organs, and organ systems.

Cellular Respiration and Tying it Together

Cellular respiration is briefly taught in seventh grade life science in Georgia. In brief, I mean to suggest that students are shown the equation:

C ₆H _{1 2}O ₆ + 6O ₂ -> 6CO ₂ + 6H ₂O

After the equation has been shared, there is little else on the subject in the curriculum, even though students in Georgia receive a 12 week session of chemistry in 8 ^th grade. This provides an additional opportunity within the framework of this unit to further explain this concept and further prepare students for the next level in science they will encounter.

By presenting concepts of the heart as the pump and the blood as the carrier of oxygen through the network of blood vessels, students will gain a clearer understanding of what is actually happening in the cardiovascular system of the body. Utilizing this unit as a counterpart to a unit on cells provides a natural outgrowth of knowledge by introducing students to different cells needed for the different tissue layers of the cardiovascular system. Once students understand that cells allow certain molecules to cross their membrane (and enter or exit the cell), they will be able to grasp the concepts of cellular respiration more readily. Students can be taught how oxygen diffusion occurs in the alveoli of the lungs to the red blood cells in the capillary system found in the lungs.

Understanding of the heart and its dynamics will help to illustrate the intricate workings of this system as a transportation network to the other organs of the body allowing teachers the flexibility to continue this process by discussing the pancreas and glucose exchange, which also utilize the circulatory system. Students can then through demonstrations in the classroom of diffusion which is also a concept students must learn. The following are some basic activities that could be used in the classroom for enriching and further explaining these concepts.

Teaching Activities

Although limited by space in this document, there are a plethora of teaching ideas and strategies that can be used for creating mastery of the concepts being taught that can be found on the Internet with a simple search. In order to provide a start and some examples of what to do the following are explored further at the end of this document.

The first is a blood pressure / pulse rate lab that is easy to complete in a classroom, but allows students to understand the reasons for intense pressure, and also why the pulse needs to be sped up at times of work compared to times at rest.

Another important aspect is understanding the velocity of the blood, and how it varies in different size blood vessels, which can be accomplished by following some simple instructions that are provided below in demonstrating how blood velocity increases and decreases based on the diameter of the vessel.

To tie everything together it is important for students to understand the concept of different size blood vessels and the diffusion of gasses across the membrane of different vessels. In order to do this there are instructions of using Jell-o to demonstrate how students can determine this in order to enhance knowledge of cellular respiration by showing the diffusion of a liquid through the Jell-O membrane.