Please note: This video goes well beyond grade 8 science. Old watch the sections on carbohyrdates, protiens, and fats (lipids).

Healthy Bodies

In this lesson we focus on how to support the different human body systems with proper diet and habits.

Blood — The Body’s Transportation System

Humans use blood to transport vital substances and wastes to cells in the body, unlike unicellular organisms that can directly exchange between the cell and the external environment. About 8% of the human body mass is blood. Plasma and red blood cells make up 99% of our blood. Plasma helps transport carbon dioxide, likewise, red blood cells transport oxygen. These red blood cells contain an iron-rich substance called hemoglobin, which attracts oxygen to the cell. The circulatory system works with the respiratory and the digestive systems to deliver oxygen and nutrients throughout the body.

The Respiratory System

The goal of this system is to absorb oxygen in exchange for carbon dioxide. Human breath in through inhalation filling their lungs with air containing oxygen. Once oxygen is absorbed the excess air is exhaled or breathed out, which rids our bodies of waste carbon dioxide. You can see the organs involved in the respiratory system in the figure below.

Digestive Health

The digestive system, with help of the circulatory system helps deliver nutrients throughout the body. Our body also breaks down carbohydrates, fats, and proteins to grow and repair our bodies, other nutrients, like vitamins and minerals are used to maintain proper function of our bodies. The process is described below:

  • Food
    • We eat food which is broken down into nutrients.
  • Nutrients
    • Carbohydrates
      • 4 Kcal per gram
    • Fats (Lipids)
      • 9 Kcal per gram
    • Protients
      • 4 Kcal per gram
    • Vitamins
    • Minerals
    • Water
  • Growth, development, and repair

Staying Healthy

You most likely heard the term, “you are what you eat” and that is very true for human digestion. Outside a few digestive disorders, it is important to eat health and well. Canada has recently started (and maybe at this time) completed the process of rewriting the Canada Food Guide. The new guidelines will focus more on fruits and vegetables, and less on wheats and meats. As you are most likely aware the systems we took a deep look at this unit (respiratory, circulatory, digestive) are vital for health bodily function. Can you think of any other activities (other than poor diet) that could affect their function?

The information on this page and it associated figures are adapted from the Science Focus 8.
Science Focus 8, pp. 157-163
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