Biology Drug Lab Techniques PROJECT OBSERVING THE EFFECT OF DRUGS ON THE NERVOUS SYSTEM AND HEART RATE Techniques and Background Information to help you plan your experiment. Drugs known as stimulants increase nerve cell activity, thereby increasing movement, heart rate, breathing, etc. Other drugs, known as depressants, slow nerve cell activity and decrease the rate of metabolism. Heart rate is a very reliable indicator of increased or decreased nerve activity. Most drugs affect the nervous system of animals the same way. To examine the effects of drugs you’ll use a small crustacean, Daphnia, which is related to shrimp and lobsters. They are also known as water fleas and live in fresh water lakes and streams. Below is a description of how to prepare Daphnia for observation. You’ll use the techniques to establish a baseline (normal heart rate for Daphnia), and to test the effects of drug solutions. SAFETY Handle all equipment and drug samples carefully. Wash your hands thoroughly at the end of lab classes. FOLLOW VERBAL and WRITTEN instructions for use of materials. Treat the Daphnia and materials with respect. I only live about 5 weeks MATERIALS: so be cool! Daphnia Petroleum jelly Microscope slides Small rubber washers Coverslips Compound microscope Clock with second hand Medicine dropper bottles for drug solutions Eye dropper for collecting Daphnia Ringer’s Solution 5ml medicine cup Data table PROCEDURE: Collecting control data 1. Create an observation chamber. Using your finger rub a small amount of Vaseline on one of the flat sides of a rubber washer. Place the washer, grease side down, on a glass microscope slide, and gently press to form a tight seal. Add 2 drops of Ringer’s Solution. Your set up should look like this: Rubber washer Slide Biology Drug Lab Techniques 2. Using a clean medicine or eye dropper, collect one Daphnia in fluid from the stock culture. Wait until the daphnia swims near the opening of the dropper and gently squeeze the Daphnia into the observation chamber. Add the coverslip to prevent evaporation of liquid. Place the slide on the microscope and observe under low power. Make sure the light source is on low power to avoid “cooking” the daphnia. eye Heart Antenna Intestine Egg pouch Feet w/ Gills 3. To collect CONTROL data, count the Daphnia’s heart beats for 10 seconds. Record this number under Trial 1 in your data table. Turn off the microscope light, and wait 20 seconds. Record the count for Trials 2 and 3, always turning off the light and waiting 20 seconds between each 10 second count. 4. Make notes of the daphnia’s activity (swimming rapidly, moving slowly, spastic twitching, etc.) 5. When done, carefully use an eye dropper to transfer the daphnia to a miniature medicine cup containing 5 ml Ringer’s solution. The daphnia should remain in the ringer solution for 2 minutes before being returned to the stock culture. Testing the effects of experimental solutions 6. Place a single daphnia in the observation chamber as before. 7. Add ONE drop of your first experimental solution to the chamber. Wait one minute while the drug takes effect. Observe the daphnia for the second minute, taking turns with your partner. Record observed behaviors. 8. After 2 minutes of total exposure, collect heart rate data as you did for step 3 above. Record all the data in the proper spaces on the data table. 9. When done, carefully use an eye dropper to transfer the daphnia to a miniature medicine cup containing 5 ml Ringer’s solution. The daphnia should remain in the ringer solution for 2 minutes before being returned to the stock culture. 10. Clean the slide and rubber washer with soap and water. Rinse thoroughly. Prepare your observation chamber with a fresh Daphnia by repeating step 1 and 2. 6. Repeat steps 7-10 for each experimental test solutions. Record all the data in the proper spaces on the data table. Biology Drug Lab Techniques Transfer this to your inquiry notes for this lab (Don’t be lazy! It will save you time later) Drug Effects Data A great general way to organize data for these experiments. Label the drug solutions you chose to study for solutions #1, #2, and #3. 10-second Heart Calculations (see calculation methods below) Rate Solution 3 Trials (10 second Ave. 10 sec Ave. 60 sec Change in Heart % difference in heart rate Observed Behavior count every 30 sec) Heart rate Heart rate rate (Experimental Heart rate (Multiply previous (Control Heart rate – control Heart rate) X 100% (A + B + C) 3 column X 6) Experimental) Control Trial 1 (A): N/A N/A Trial 2 (B): Trial 3 (C): Solution #1 Trial 1 (A): Trial 2 (B): Trial 3 (C): Solution #2 Trial 1 (A): Trial 2 (B): Trial 3 (C): Solution #3 Trial 1 (A): Trial 2 (B): Trial 3 (C): GRAPHING DATA: Create Graph that will help you compare the control group to the experimental groups. You must decide if a Bar or Line graph is more appropriate. Also you need to decide what data is most useful to compare: Ave. 60 second heart rate or % difference (change) in heart rate.
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