Introduction to the Lesson

[Bernard NebelKeymaster]

Have kids consider: With the skeleton, muscles, and nervous systems, (Lessons B-7 & 8) we have the shape, form, and function of an animal. Cover it with skin and what else do you need? Discuss! Bring kids to recognize the need for ENERGY to make the systems go/work. No less is the need nutrients for growth, maintenance and repair of the systems.

Stress that food is the necessary input for energy as well as nutrients for growth. The molecules of food have high potential energy. As food molecules are oxidized (“burned”) their potential energy is released (glucose C6H12O6 + oxygen 6O2 —> carbon dioxide 6CO2 + water 6H2O plus energy). The reaction is the same as burning wood in a fireplace. However, in the body energy is released in a form the makes cells “work”, e.g., muscle cells contract, nerve cells send signals, etc. Breathing accomplishes both the intake of oxygen and the release of carbon dioxide. Finally, there are additional wastes that result. These must be gotten rid of.

The key fact is that the oxidation of food molecules and release of energy takes place and only takes place in each and every individual cell of the body. Therefore, the basic problem, stress to kids, is taking materials from points of entry (nose and mouth) and distributing them to each and every cell of the body. Likewise, waste products, e.g. carbon dioxide, must be collected from each and every cell and taken to a point of exit from the body. All the internal organs of the body are concerned with these tasks.

The circulatory (blood) system is the system concerned with this transport of materials from one place to another in the body. However, ask kids if they see problem in this. It is basically: How do materials enter and/or exit the blood at specified locations?

In the following sections, we have videos that address the major organ systems of the body. I recommend omitting technical terminology and names of particular parts. However, give special attention to the fine structure that facilitates the transfer of material from the organ to the blood, or exit of material from the blood to the organ or tissue. In so doing, keep the focus on the central principle: We are providing muscle cells, nerve cells, brain cells, and the countless other cells of body with the energy they need to do what ever it is they do, with the nutrients they need for maintenance, repair, and growth, and removal of wastes.

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