2.3.1 blood circulatory system

Figure 13. The contraction of the heart and the action of the nerve nodes located on the heart. Images from Purves et al., Life: The Science of Biology , 4th Edition, by Sinauer Associates ( www.sinauer.com ) and WH Freeman ( www.whfreeman.com ), (please get permission)

Electrical activity

• The electrical activity in the heart is so strong that is can be measured from the surface of the body as an electrocardiaogram (ECG).
• A normal heart has a very regular rhythm.
• An abnormal heart may have an arrhythmia, or abnormal rhythm as shown in the figures.

Figure 15. Normal cardiac pattern (top) and some abnormal patterns (bottom). Images from Purves et al., Life: The Science of Biology , 4th Edition, by Sinauer Associates ( www.sinauer.com ) and WH Freeman ( www.whfreeman.com ), (please contact for permission).

Investigation: Heart Health and Measuring Heart rate

Part 1: Investigating your cardiovascular fitness

Aim :To investigate your heart rate before, during and after strenuous aerobic exercise.

Method :

1. Work in pairs on the field and ensure you have a stop watch.
2. One partner performs the experiment and the other records the results. Partners then swap roles.
3. Take the resting pulse rate before exercising.
4. One partner runs quickly around the field twice.
5. Immediately after the run take his pulse.
6. Continue to take his pulse every minute for 5 minutes.
7. Record the results and plot a graph using the data pertaining to you.

Results : Record results in a table like the one indicated below

Draw a line graph to illustrate your results on the following axis (show the resting pulse rate as a separate dotted line on the axis).

Mark allocation: heading x-axis scale x-axis label 

y-axis scale y-axis label plotting graph 

neat and done in pencil 

Questions:

1.Write a hypothesis for this investigation.

2.Write down the independent variable.

3.Write down the dependent variable.

4.Name ONE factor that must be kept constant during this investigation.

5.Write down TWO ways in which the accuracy of this investigation can be

improved.

6.What conclusions can be made about your cardiovascular fitness?

7.Explain why the heart rate increases during exercise?

Part 2: Investigating your family’s heart health:

Instructions:

1. Draw up a table to record the answers to the following yes/no questions:

i. Do you smoke?

ii. Are you overweight?

iii. Do you exercise regularly?

iv. Do you follow a healthy diet (low fat, low salt)

v. Do you have your blood pressure checked regularly?

vi. Do you have a family history of heart and circulatory disease?

1. Survey two adult male family member (father, grandfather or uncle) and two adult female family members (mother, grandmother or aunt). Include the adults’first name, gender, age and relationship to you.

3.Record the results in your table. Also indicated the score they obtained:

i. yes=0; no=5

ii. yes=0; no=5

iii. yes=5; no=0

iv. yes=5; no=0

v. yes=5; no=0

vii. yes=0; no=5