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Procedure

  1. Measuring Circulatory System Function in Humans
    • Before starting the experiment go to the front of the room and collect an alcohol swab, a sphygmomanometer, and a stethoscope.
    • Clean the earpieces with the alcohol swab and then insert them into your ears.
    • To check if the stethoscope is in the on position, gently tap the flat metal disc called the diaphragm.
    • If you hear a sound it's on. If not, turn the metal disc and tap again and keep turning and tapping the disc until you hear a sound. NOTE: For this experiment you will work in pairs. One person will measure their partner's blood pressure, while the person being measured will count their heartbeats over the course of one minute.
    • Fill out table one with the name of the person being monitored. HYPOTHESES: The experimental hypothesis is that systolic blood pressure will be higher when the person is sitting when compared to lying down because more pressure is required for blood to be moved around the body. The null hypothesis is that there will be no difference in systolic blood pressure whether a person is sitting or lying down.Click Here to download Table 1
    • The person being monitored should begin by lying down. Next, they will need to locate their pulse by placing two fingers next to their windpipe. If a throbbing sensation is felt, this is the pulse.
    • Now, ready a time keeping device to count out 1 minute as the person taking their pulse will be having their blood pressure taken at the same time.
    • At this point, the person measuring blood pressure should place the cuff of the sphygmomanometer around the other arm of the subject and the stethoscope earpieces into their own ears.
    • Start the timer.
    • The person being monitored should begin counting the number of heartbeats felt over one full minute. While the subject is taking their pulse, the person taking blood pressure should place the diaphragm of the stethoscope under the cuff on the inside of their partner's elbow.
    • Then, pump the cuff to 200 mm of mercury.
    • Gently and slowly twist the metal knob on the sphygmomanometer to release air from the cuff.
    • As pressure is released the first Korotkoff sound should be heard. The corresponding value on the sphygmomanometer is the systolic blood pressure. Consistent sounds should be heard until they die out with the last sound signifying the diastolic blood pressure.
    • Record the systolic pressure, the diastolic pressure, and the heart rate in Table 1.
    • Now, repeat the blood pressure and pulse measurements with each partner keeping the same role but this time the subject should be sitting upright.
    • Record these data in the appropriate places in Table 1.
    • Finally, the partners should switch spots. So now, the person measuring blood pressure should be taking their pulse and acting as the subject. NOTE: Be sure to wipe the earpieces of the stethoscope between users and don't forget to record your measurements in Table 1.
    • After finishing the experiment, discard all alcohol swabs into the trash. Then, bring the sphygmomanometer and stethoscope back to the front of the room.
  2. Measuring Respiratory Rate in Fish
    • To prepare for this second experiment, collect two clear containers.
    • Begin by filling half of one container with aquarium water.
    • Then, use a fish net to gently catch a goldfish and place it into the cup. Pinch the net around the fish or else it may jump out of the net.
    • Familiarize yourself with the operculum of the fish. The operculum covers the gills and it is located behind and below the eye. When the fish respires the operculum moves in and out and this is one gill beat. HYPOTHESES: In this experiment you will measure the gill beats of the fish in different water temperatures. The hypothesis is that there will be a significant correlation between the temperature and respiration rate in goldfish. The null hypothesis is that there will be no correlation between temperature and respiration rate.
    • Take the other empty container with a screw cap, the cup with your fish, and the net to the water tanks.
    • Then, fill the empty container with the water from the lowest temperature water bath. This will act as your first respiration rate chamber.
    • Next, hold the fish net over a wastewater container and dump out the water from the cup holding the fish so that the fish falls into the net. Pinch the net around the fish without touching the fish itself.
    • Bring the net over the top of the container with the bath water and let go of the net to release the fish into the vial.
    • Once the fish is in the container, submerge it back into the water bath and then screw the cap on to prevent outside oxygen from entering the vial.
    • Next, remove the container from the controlled temperature water bath and place it on your workbench surface to avoid warming the water with body heat.
    • One partner should immediately begin counting the gill beats as soon as the second partner starts the stopwatch.
    • Continue counting the beats for 20 seconds. Record the number of beats in column A of Table 2. Click Here to download Table 2
    • Repeat the measurement one more time and record the number in column B.
    • Next, hold the fish net over a wastewater container and dump out the water from the fish vial so that the fish falls into the net. IMPORTANT: Move from lowest to highest temperature, so the fish is not stressed between trials.
    • Repeat the experiment for the remaining four temperature conditions (steps 8 – 13).
    • Record all the values for different temperatures in Table 2.
    • Once you are done, slowly mix water from the last respiration chamber with the fish tank water and then return the fish to the home tank. NOTE: This should be done over the course of approximately 10 minutes.
  3. Results
    • It's time to analyze the data that you just collected. Look at the blood pressure and heart rate measurements for the different trials. If they were different, make a hypothesis to explain your observations.
    • For the gill beat experiment, average the numbers in columns A and B and calculate the fish respiration rate as gill beats per minute.
    • Next, plot the graph of temperature versus gill beats per minute.
    • Record any correlations you see between the variables. If a correlation is observed, determine if it is positive or negative and provide an explanation for this result. NOTE: Consider the fact that fishes are ectotherms and the impact of temperature on dissolved oxygen.

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