INVESTIGATION OF THE CARDIOVASCULAR SYSTEM
Aim: to investigate the effect of different age on heart rate.
Hypothesis: As age increases the heart rate decreases.
Independent variables: Age of subject
Dependent variables: Heart rate (bpm)
Controlled variables: Method of taking subjectsâ€™ heart rate
â€¢ Stop watch
â€¢ Pencil and paper to record
â€¢ Select 30 subjects from different age group (10-19, 20-29, 30-39, 40-49, 50-59)
â€¢ Using a stethoscope and placing to the left of the sternum
â€¢ When the beats can be heard clearly, count them for 15 seconds using stop watch and record it
â€¢ Multiply the heart HR by 4 to ...view middle of the document...
The procedure of the experiment was altered after measuring a few subjectsâ€™ heart rates, because it was hard to hear the beats of the elder subjects. Because of that most of the subjectsâ€™ heart rates were measures from their pulse on their wrists. This is one of the weaknesses.
On table result, one of the subjectâ€™s heart rate in 40-49 age group is 84 and itâ€™s not very close to the other subjectsâ€™ heart rate, so that could be an outlier. It has made a big difference on the average heart rate of that age group, this can also be one of the weaknesses.
One of the Improvements to the experiment design would be to ensure that participants were sitting and relaxed for 5 minutes before the measuring the heart rate, the other one would be interviewing the subjects to investigate whether there were any prior heart conditions.
One of the strength of this experiment was that it didnâ€™t need many equipments and it was done in a double lesson.
The procedure was first based on 5 intervals for age groups, but it was really hard to find people in some different age group so it was changed to 10 intervals. The method could be improved by having many people in different age groups for the subject. The average result will be more accurate.
The analysis supports the hypothesis. As age increases the heart rate decreases. This is because the heart muscle becomes less efficient at pumping blood around the body, the walls of the heart becomes more rigid, and it takes longer for the heart to fill with blood, therefore less beats per minute. Although age is only one of the factors that has effect on heart rate, there are many other factors that effect on heart rate such as Medication, sleeping, infection, rest, stress and exercise.
â€œEffects Of Agingâ€, 2005, My Doctor, UBM Australia, viewed 10/10/2010, http://www.mydr.com.au/seniors-health/animation-effects-of-ageing
Sherwood. C, 2009, â€œWhat effects On Heart Rateâ€, eHow.com, viewed 5/10/2010, http://www.ehow.com/about_us/about_us.aspx
1. What causes your pulse?
A pulse is a series of pressure waves in a artery, caused by contraction of the left ventricle of the heart. So during each heartbeat, the muscles of the heart contract causing a wave of pressure which forces blood through the arteries. 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.
2. Why does heart beats faster during exercise?
When we exercise we use our muscles to work. To do so there is more energy needed in form of glucose and oxygen. As we exercise more the demand of glucose and oxygen increases, so the heart needs to pump the blood faster, so that our muscles can receive the...