Physiology of the Circulatory System - Part 2

Heart Rate and Temperature Study in Daphnia Magna

Hypothesis: If a Daphnia is placed at different temperatures, then its heart rate will either decrease or increase.

Materials:

• Dissecting Microscopes
• Thermometers
• Timer
• Petroleum Jelly
• Triangular File
• Alcohol Swab
• Towel

Procedures

1. Using a large bore plastic transfer pipet, pipet some liquid containing Daphnia from the container your teacher has provided.
2. Hold a 9” glass Pasteur pipet over a petri plate or jar containing the Daphnia culture. Tilt the Pasteur pipet and pipet the Daphnia and liquid into the end with the larger opening. Allow the solution and the Daphnia to flow down into the narrow end of the pipet. The Daphnia should become stuck in the pipet.
3. If needed, use a paper towel to blot out the excess solution from the narrow pipet end until the Daphnia is lodged in the narrow of the Pasteur pipet. Keep the solution just about 1 cm above the Daphnia.
4. To fit into a petri plate, you will have to shorten the pipet a few inches.
5. Score (scratch) the pipet with a triangular file one inch above the point where the Daphnia has become stuck.
6. To protect your hands, wrap a paper towel around the pipet and break it where you have placed the score mark.
7. Seal the bottom, narrow end of the pipet by pushing it slightly into petroleum jelly.
1. Add more Daphnia culture liquid to the pipet so that there is approximately 0.5 inches of liquid above the Daphnia.
2. Seal the other open end of the pipet with petroleum jelly.
8. Place the pipet containing the Daphnia into a petri plate containing 20 ml of water, which is at the same temperature as the Daphnia culture liquid. Record the temperature.
9. Place the petri plate under a dissecting microscope and locate the Daphnia’s Heart. Count the number of heartbeats for 10 seconds. Multiply by 6 to determine the number of beats per minute.

10. Now place the pipet containing the Daphnia into a petri plate containing 20 ml water at approximately 5oC. Measure the temperature and determine the heart rate beats per minute.
11. Record the data for temperature and heartbeats per minute in Table 10.
12. Carefully add warm water to the dish to raise the temperature approximately 5o C. Record the actual temperature and then measure the heart beats per minute.
13. Continue adding additional warm water and record the temperature and heart rate every 5oC.
14. Repeat the procedure until you are unable to measure the heartbeat accurately. Keep recording the data until you stop.
15. Plot the heart rate in beats per minute versus the temperature on linear graph paper. Label the X-axis temperature. Label the Y-axis heart beats per minute.
16. Determine the Q10 for your Daphnia using the following equation:

In this lab, Q10 = 2.2

Table 10: Temperature and Heart Rate
Temperature in Degrees Celsius	Heart Rate
25	72
5	30
10	84
15	132
20	180
25	132

Justification:  This table shows the heart rate of the daphnia at different temperatures. It seems like as the temperature increases, the heart rate does too. Since we did need to use two different daphnias to record the results, the fist two temperature measurements do not fit with the rest of the results. 

Justification: This graph shows the heart rate of a Daphnia in different temperatures. It shows the results of the experiment that tested the hypothesis, “If a Daphnia is placed in different temperatures, then its heart rate will either decrease or increase.” The independent variable (the x-axis) would be the temperature and the dependent variable (the y-axis) would be the heart beats per minute.

Analysis Questions:

1. Why does the Daphnia’s heart slow down at lower temperatures?
1. The Daphnia’s heart rate slows down at lower temperatures because they are cold-blooded. Their body temperature becomes the same as the temperature in their environment. If the environment had a lower temperature, then the Daphnia’s metabolism would also be low which would slow down its heart rate.
2. Why does the heart rate of endothermic, warm-blooded organisms, such as man, remain relatively unaffected by changes in the environmental temperature?
1. The heart rate of endothermic organisms remain unaffected by changes in environmental temperature because they regulate their body temperature in order to maintain homeostasis. When it is cold, endothermic organisms keep their body heat insulated in their body. When we put on a sweater, it isn’t to keep out the cold, it is to keep heat from escaping our bodies. Unlike cold-blooded organisms, warm-blooded organisms do not have fluctuating body temperatures; they have a single body temperature to maintain.
3. How do ectothermic, cold-blooded organisms, such as the Daphnia regulate their temperature? Can you give examples from nature?

Ectothermic organisms regulate their temperature by taking the temperature of their surrounding environment. This means that if it is 20 degrees celsius, the organisms temperature will be 20 degrees celsius. If a lizard wants to increase its metabolism, it will bask in the sun to increase its temperature. When it gets too hot, it goes in the shade and it cools down.

In conclusion, the Daphnia's heart rate is lower at colder temperatures and is higher at warmer temperatures. This proved my hypothesis, "If a Daphnia is placed at different temperatures, then its heart rate will either decrease or increase" was correct. Since Daphnia are cold blooded, they take the temperature of the environment they are in which affects their metabolism. An error that could have occurred was if we counted the heart beats incorrectly. Also, the data we collected does not match well because we had to use to different Daphnia. If this experiment were to be performed again, one thing that could change would be the type of organism that was used.

Physiology of the Circulatory System - Part 1

Hypothesis: If a sphygmomanometer and a stethoscope are used on a person, then their blood pressure would be identified.

Materials:

• Stethoscope
• Sphygmomanometer
• Timer
• Stool

Procedures

1. Blood Pressure Measurement
1. Students should be placed into groups.
2. The student who is having their blood pressure measured should be sitting down in a relaxing position.
3. Another student will perform a measurement by placing the inflated cuff of the sphygmomanometer around the sitting student's arm beginning just above the elbow. It should be firmly secured and positioned so that the inflation tubing is easily accessible by the person measuring the blood pressure.  
4. Close the valve in the rubber bulb and inflate the cuff by depressing the bulb. The gauge should go up to about 200mm HG.
5. The individual performing measurements should put on the stethoscope and place the “microphone” end just below the cuff but above the bend of the elbow over the brachial artery.
6. Slowly begin to release pressure by gradually opening the valve. The person measuring should carefully listen for the first sound of a pulse from the collapsed antecubital artery in the arm.
7. Note the pressure when the first sound is heard. This is systolic pressure. Continue listening and when the sound fades note this pressure. This is the diastolic pressure.
8. Make two additional reading and determine an average for systolic and diastolic blood pressures. Record these values.
2. Reclining versus Standing Systolic Blood Pressure
1. The person being measured should lie down on a blanket placed on the laboratory bench or floor and allow blood pressure to equilibrate for 5 minutes.
2. Measure the reclining systolic and diastolic blood pressure as in Part A. Take two readings and record the average as systolic/diastolic in mmHg.
3. Ther person should then stand up and remain motionless for 3 minutes.The blood pressure should again be measured twice and recorded. Make sure to record the average.
4. By subtraction, determine the difference between the reclining and standing pressures.
5. Assign fitness points based on the values in Table 2 and record them.

6. Continue with the next part with the same person.

3. Standing Pulse Rate

1. The person being measured should stand motionless for 2 minutes.
2. The measurer should determine the person's pulse rate. Place your first finger on the person’s wrist, above the thumb. You should feel for a strong pulse. Do not use your thumb since it has a pulse of its own. Count the beats for 30 seconds and multiply by 2 to get the rate per minute. Repeat a second time and compute the average.
3. Using table 3, assign and record the fitness points.

4. Continue with the next part with the same person.
4. Reclining Pulse Rate
1. The person being measured should recline motionless for 5 minutes on a laboratory bench or floor and remain lying down.
2. The measurer should then determine the person’s pulse rate. Measure the pulse for 30 seconds and multiply by 2 to get the rate per minute. Repeat a second time and compute the average.
3. Assign and record fitness points using table 4.

4. The student being measured should remain lying down to continue to the next part.

5. The Baroreceptor Reflex
1.  The person being measured should stand up and the measurer should immediately determine the person's pulse rate. Measure the pulse for 30 seconds and multiply by 2 to get the rater per minute. Record that value.
2. Subtract that value from the standing pulse rate and record it.
3. Assign record fitness points using table 5.

6. The Step Test for Endurance
1. Obtain a step stool from your teacher. Work in groups of 4. One student is tested while the other students take measurements.
2. Place your right foot up on the stool and step up with your left foot. Immediately return your left foot to the ground. Repeat the stepping exercise for 4 additional cycles. Allow approximately 3 seconds for each stepping cycle.
3. Once the last cycle is complete, return both feet to the floor. Stand motionless and immediately measure your heartbeat for 15 seconds. Multiply this value by for to get beats per minute. Continue counting from zero and again record the number of beats after another 15 seconds. Continue measuring your pulse and record rates at 60, 90,  and 120 seconds. Continue measuring until your heart rate returns to your standing pulse rate.
4. Stop measuring after 150 seconds. Assign and record a fitness score based on Table 6, for the time required to return to the standing rate. You get 0 points if your pulse is 1-10 beats per minute above standing rate after 150 seconds. You get -2 points if your pulse is less than 11 beats per minute above standing rate after 150.

5. Determine the difference between your normal standing pulse rate and the pulse rate for the 0-15 second interval measured immediately after stopping exercise.
6. Subtract the value in beats per minute while standing from the value in beats per minute determined for the 0-15 second interval. Record the value.
7. Use table 7 to assign and record the fitness score.

8. Record all the data gathered in table 8 and determine your cardio fitness from the total score in Table 8 using Table 9.

Table 8
Experiment Test	Measurement	Points
Part B. 1 Blood Pressure Changes	8/11 beats	6
Part B. 2 Standing Heart Rate	76 beats per minute	6
Part B. 3 Reclining Heart Rate	55 beats per minute	6
Part B. 4 Baroreceptor Response	70 beats per minute	6
Part B. 5 Step #6	46 to 60 seconds required to return to normal standing rate.	6
Part B. 5 Step #9	32 beats	0
	Total Points:	30

Justification: This table shows the heart rate while in different positions, such as standing up or reclining. It shows that when one is standing up, the heart rate is higher than when they are reclining. Also, this shows the fitness points that are associated with these measurements. The total points at the bottom show that this person has a good fitness score overall.

Analysis Questions

1. Why does blood pressure vary among different individuals?
1. Blood pressure varies among different individuals because it is affected by the individual's age or their health. Since not everyone is the same age, they have different blood pressures. As one gets older, their blood pressure may increase. If an individual is healthy, then they most likely have a normal blood pressure; however, if they are not healthy their blood pressure may be too high.
2. Why does a poor score on the Fitness Test mean?
1. A poor score on the fitness test means that the individual is not really healthy. It is more likely for them to die from heart diseases and have high blood pressure. They may have an unhealthy lifestyle and in order to improve their score, they must live healthier.
3. Why are standing, resting, and exercising heart rates different?
1. When an individual is standing, gravity pulls the blood down so the heart must work a little bit harder to keep it flowing throughout the body. When an individual is resting, they are laying down which makes it easier for the heart to pump blood. This is why the heart rate becomes lower while resting. When one is exercising, the body needs oxygen so the heart rate increases to deliver the oxygen more quickly.
4. Why are athletes capable of delivering more oxygenated blood to their body?
1. Athletes are more capable of delivering more oxygenated blood because since they train their bodies, their hearts are stronger and become enlarged. Whether the athlete is exercising or not, their heart is capable of delivering more blood to their body than an untrained heart.
5. Why does an athlete have to work harder to achieve a maximum heart rate?
1. An athlete has to work hard to achieve a maximum heart rate because they are constantly exercising. When athletes exercise, their bodies demand more oxygen so by increasing their heart rate, athletes are able to deliver oxygen more quickly through the blood. If an athlete had a low heart rate, they wouldn’t perform very well.

In conclusion, heart rate varies from person to person. Since they live different lifestyles, their health is affected differently. If one lives a healthy life, they will most likely have a lower blood pressure while a person with an unhealthy life will have a higher blood pressure. Heart rate and blood pressure are affected by an individual's activity. For example, if they are exercising, their heart rate will increase; if they are sleeping their heart rate will decrease. Some errors that could have occurred are if we measured the blood pressure incorrectly or if we calculated the measurements incorrectly. If this experiment were to be repeated, one thing that could be changed would be to change the type of exercise that was performed.