Biology
Standard III, Objective 2
Title: Testing an Organ System
Description: Students will choose an organ or organ system and design an experiment to test it.
Materials: will vary depending on what you have. Ideally: blood pressure cuff, stethoscopes, lung volume bags, breath control analyzer (measures how long you can blow steadily into a tube) grip meters, oral thermometer and alcohol cleaning solution, meter stick, clock with second hand or stopwatches.
Time Needed: 30-50 minutes for student to choose activity and set up their experiment. 30 minutes to collect data, 30 minutest to report results
Procedures:
1. Gather the materials available. Your health teacher may have things you never dreamed of in a closet. Barbara Gentry at JSD can also lend you items. Many grocery store pharmacies have blood pressure machines and occasionally a bone scan is performed there also.
2. Show your students the materials and describe their use. You might call a health professional to come and talk to the class about the measurements and what they mean. Make an overhead of the list printed below to guide the discussion.
3. Place students in groups of 3 or 4 and hand out the student sheets.
4. Read over the sheets with students and make sure they understand their assignment.
5. Have students pick their system or instrument they will use. Two groups may do the same measurement if you have enough equipment. Make sure they test a different variable.
6. Check student-designed experiments. Check for groups that attempt to test two variables, a common mistake. They should repeat the experiment enough times to trust their results.
Measurements of Body Systems
Nervous System-Reaction time:
Computer simulations
ruler drop Get a ruler (or a meterstick). Hold the ruler near the end (highest number) and let it hang down. Have another person put his or her hand at the bottom of the ruler and have them ready to grab the ruler (however, they should not be touching the ruler). Tell the other person that you will drop the ruler sometime within the next 5 seconds and that they are supposed to catch the ruler as fast as they can after it is dropped. Record the level (inches or centimeters) at which they catch the ruler (you can convert the distance into reaction time with the chart below). Test the same person 3 to 5 times (vary the time of dropping the ruler within the 5 second "drop-zone" so the other person cannot guess when you will drop the ruler).
Here is a table to convert the distance on the ruler to reaction time. For example, if you caught the ruler at the 8 inch mark, then your reaction time is equal to 0.20 seconds (200 ms). Remember that there are 1,000 milliseconds (ms) in 1 second.
DistanceTime
2 in (~5 cm)0.10 sec (100 ms)
4 in (~10 cm)0.14 sec (140 ms)
6 in (~15 cm)0.17 sec (170 ms)
8 in (~20 cm)0.20 sec (200 ms)
10 in (~25.5 cm)0.23 sec (230 ms)
12 in (~30.5 cm)0.25 sec (250 ms)
17 in (~43 cm)0.30 sec (300 ms)
24 in (~61 cm)0.35 sec (350 ms)
31 in (~79 cm)0.40 sec (400 ms)
39 in (~99 cm)0.45 sec (450 ms)
48 in (~123 cm)0.50 sec (500 ms)
69 in (~175 cm)0.60 sec (600 ms)
Nervous System-nerve receptors in skin
2 point discrimination exam. Bend a paper clip into the shape of a U with the tips about 2 cm apart. Make sure the tips of the U are even with each other. Lightly touch the two ends of the paper clip to the back of the hand of your subject. Your subject should not look at the area of skin that is being tested. Do not press too hard! Make sure both tips touch the skin at the same time. Ask your subject if he or she felt1 or 2 pressure points. If your subject reported 1 point, spread the tips of the clip a bit further apart, then touch the back of the subject's hand again. If your subject reported 2 points, push the tips a bit closer together, and test again. Measure the distance at which the subject reports "I feel 2 points".
Muscle Strength or endurance-grip meters or tennis balls
Grip meters or number of squeezes on a tennis ball until muscle fatigues.
Skeletal-bone scan (will involve out of class work)
Students must locate a machine that does bone scans.
Respiratory-lung volume
Lung Volume bags measure the amount of air breathed out by the lungs.
Respiratory-breath control
Breath control devices measure how long you can exhale air in a controlled manner.
Respiratory-breath rate
Count the number of breaths per minute
Circulatory-heart rate
Take the pulse or number of beats per minute of the heart.
Circulatory-blood pressure
Will require a blood pressure cuff or visit to pharmacy with one.
Muscular/nervous-balance and coordination
Standing Stork Test
To undertake this test you will require :
* Stop watch
* An assistant
How to conduct the test
* Stand comfortable on both feet
* Hands on your hip
* Lift one leg and place the toes of that foot against the knee of the other leg
On command from the assistant:
* Raise the heel and stand on your toes
* Assistant starts the stop watch
* Balance for as long as possible without letting either the heel touch the ground or the other foot move away from the knee.
* Assistant records the time you were able to maintain the balance.
Repeat the test for the other leg.
Body temperature
Oral thermometer measures body temperature.
Student SheetName______
Introduction: The human body is a marvelous network of cells, tissues, organs and organ systems. Most of its inner workings are hard to measure without sophisticated tests some of which you may have had done at a doctors office. There are a few measurements that can easily be performed in a school setting. In this activity you will be introduced to the tests, choose one and design an experiment to test one variable concerning the system or organ.
Procedures:
1. Decide with your group which measurements you wish to make. We chose:
2. What variable will you test?
3. What is your control?
4. What is your hypothesis: (use an “if….then” statement)
5. Describe your procedures completely:
a.
b.
c.
d.
e.
f.
g.
teacher approval before you begin: ______
Data:
Analysis:
1. What did your results show?
2. How accurate or trustworthy are your findings?
Why?
3. What would need to be done to improve your experiment?
4. How does the organ or system you tested interact with other body systems?
5. How does the organ help maintain homeostasis in the body?
Conclusion: