Cellular Respiration Module:
Connecting The Three Body Systems
Digestive, Respiratory and Circulatory
Driving Questions:
Have you ever though about why we eat and breath?
How do our bodies use food and oxygen to get energy?
How does this happen within our cells?
Story:
Our bodies need food and oxygen to get energy. How do our cells get the energy from food
and oxygen?
Eric and Roger are classmates and good friends. Both are 12 years old and exercise
regularly. Their science assignment is to figure out how the human body uses food and oxygen to
get energy. They were asked to run (as a form of exercise) and measure the following:
(1) the rate of muscle cell contractions;
(2) how much carbon dioxide (CO2) they exhaled (breathed out);
(3) their average body temperature; and
(4) how much oxygen (O2) they inhaled (breathed in
Eric and Roger took note of what they ate before running. Then they went running
together. They were each given the measurement instruments they needed. Here are their
measurements and their body conditions:
The following table is a comparison of Eric and Roger’s physical condition.
Table (1) Physical Fitness
Eric
Roger
Height (cm.)
158
161
Weight (kg.)
52
50
Exercise
regularly
regularly
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What to do in pairs:
(1) Look at the data about Eric and Roger.
(2) Fill out the first column of the study worksheet and explain you can conclude about
each graph or table shows starting with study number 2. In other words what is measured
and what is changing over time
This study describes muscle contraction in the presence of varying levels of sugar and oxygen.
Figure (1) Muscle Cell Contraction during Exercise
Microscopic view of muscle cells
Note: when we use muscles, like doing exercise, the muscle cells in the muscle contract
(tighten). The harder the exercise, the faster the muscles contract.
Rate of Muscle Cell Contractions
2
This figure compares the amount of carbon dioxide Eric and Roger exhale while exercising.
Figure (2) Exercise and CO2 Exhaled (breathed out)
KEY: -------- Eric
- - - - - Roger
This table is the comparison of body temperature for Eric and Roger as they run.
Table (2) Body Temperature during Run
10 min.
20 min.
30 min.
40 min.
Eric
36.7
36.9
37.4
38.0
Roger
36.6
36.9
37.2
37.8
**Note: Body Temperature in Degree Celsius
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This figure compares the amount of oxygen Eric and Roger inhaled while exercising.
Figure (3) Exercise and O2 Inhaled (breathed in)
KEY: -------- Eric
- - - - - Roger
However, for some reason Eric could not keep up with Roger’s running pace after a
while. They are in similar physical condition, so what could be the reason? Eric thought that it
might have to do with what they ate before running. Eric had a big steak beforehand, and Roger
had pasta and a fruit cup instead. Below is the graph describing how long they ran based on
different foods they ate.
Figure (4) Low-Carb Runner vs. High-Carb Runner
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Remember Eric and Roger’s assignment was to link their measurements to how
our bodies use food and oxygen to get energy and how this happen within our cells.
**Note-
This figure compares the density (amount/cell)
of various organelles in Eric and Roger’s muscle
cells.
Figure (5) Cellular organelles
Organelles
Nucleus
Mitochondria
Ribosomes
Endoplasmic
reticulum
Eric
normal
normal
normal
normal
Roger
normal
slightly high
normal
normal
Finally
We will discuss each study together in class to be sure we are interpreting the
data correctly
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