THE HEART AS A PUMP – Predict-Observe-Explain Write-Up
Alenna Jamieson
Source:
http://www.smm.org/heart/lessons/lesson1.htm
Main Concepts
- Students will measure their heart rate and observe how it changes with
exercise (data analysis practice)
- Students will observe and begin to understand the integrated role of the
circulatory system in meeting the human body’s energy demands
Materials
- Stopwatch – for 10 second intervals, 1 and 2 minute intervals I used online
stopwatch http://www.online-stopwatch.com/timer/10seconds/ , you could
borrow a stopwatch from the gym, use your phone etc.
- Space
- Chair
Safety
- Ensure there is adequate space for a student to do physical activity
- Adaptations for students with physical limitations- change the activity from
jumping jacks to running on the spot or touching toes (with raising arms in
between)
Set up
- Clear enough space for 1-2 students to do physical activity
- Have stopwatch ready (online stopwatch in this case displayed on screen)
- Set up chair beside board
- Print out enough worksheets for the students
What will happen (if everything goes right):
- Students will take a baseline measurement of their heart rate, an exercising
measurement (after doing 1 minute of exercise) and a post-exercise measurement.
They will see that their heart rate increases with exercise and decreases after a
short rest period.
Common hang ups – Students are nervous when beginning the protocol and
because of this, their resting heart rate is already quite high. As long as the exercise
is exerting enough to raise their heart rate higher than the starting heart rate, this
won’t be a problem. Also, students are nervous (or out of shape) and do not recover
as fast as expected (within 2 minutes given). You could give them an extra minute or
two to recover. This could be used for a discussion of heart muscle health or other
factors that contribute to increases in heart rate (such as hormones like adrenaline.)
The majority of students, however, should recover within the 2-minute time frame.
Why it happens –
Reference:
Boron, W. (2008). Chapter 22: The Cardiac Cycle. In E. B. Water Boron, Medical
Physiology (Vol. 2). Elsevier Health Sciences.
During each heartbeat, the muscles of the heart contract causing a wave of pressure
which forces blood through the arteries. This wave of pressure is known as a pulse.
There is one pulsation for each heartbeat.
The pulse can be felt at various points on the body where the arteries are just under
the skin, such as the temples, neck, crook of the elbow, wrist, groin, back of the knee,
and the inside back of the ankle. The normal pulse rate varies with age.
The heart acts as a pump to send blood to other parts of the body. When you breathe
in, oxygen from the air enters the blood through the lungs. Blood carries oxygen to
cells in tissues, like muscles, and organs, like your brain. Oxygen is used as a fuel to
create energy for the body. Carbon dioxide (CO2) is produced as waste in the energymaking process. CO2 can poison your body if you have too much of it, so your blood
picks it up and travels from the tissue and organs and is pumped through the heart
and to the lungs, where CO2 leaves the body when we breathe out.
During physical activity, muscles use up the body’s energy faster. There is a higher
need for energy, therefore for more oxygen as a fuel to produce this energy.
There are two ways the heart can meet the body's need for oxygen during exercise.
It can beat faster or it can beat harder, moving more blood per pump. (But it can
only beat harder if it has been strengthened through regular exercise.) In this
exercise students will find that their hearts beat faster to meet the energy demands
of the body. Their hearts will pump faster to deliver more oxygen to tissues and
expel the increased amount of CO2 that is being produced during exercise.
Curriculum fit –
Saskatchewan- Grade 8:
CS8.4 Analyze how the interdependence of organ systems contributes to the healthy
functioning of the human body. [CP, DM, SI]
Manitoba- Grade 8 :
• 8-1-14 Describe, using examples, how individual systems in the human body
function interdependently. GLO: D1, E2
• 8-1-15 Compare heart rate and respiratory rate before, during, and after
various physical activities; explain the observed variations; and discuss
implications for overall health
Alberta- Grade 8:
3. Interpret the healthy function of human body systems, and illustrate ways the
body reacts to internal and external stimuli
Connection to another topic in Saskatchewan curriculum:
Mathematics Grade 8 – “Analyze the effectiveness of data representations related to
the healthy functioning of the human body. “
This activity also can tie into the Physical Education curriculum (ex. Physical
Education outcome 8.1- Health Related Fitness).
Questions to Assess: (also see other file for the complete worksheet)
1. How did your heart rate change when you went from rest to exercising?
2. How did your heart rate change when you went from exercising to resting?
3. Do you need more or less energy when you are physically active? (ex.
Exercising)
4. Do you need more or less energy when you are at rest? (ex.sitting in a chair)
5. What is one of the “fuels” that humans need to make energy?
6. What is the “waste” that is formed when we make energy?
7. In your own words, explain why your heart rate increases (ie. pumps blood
faster) when you exercise and why it decreases when you are at rest. (Hint –
think about what your body needs during exercise, and also the waste it needs to get rid of.)