The Effect Of Acetylcholine On The Heart Rate Of Daphnia Magna
The Effects of Temperature, Acetylcholine, and Adrenaline on the Heart Rate of Daphnia magna
Hieu Duong
6 April 2011
Introduction The heart is a muscular organ that constantly pumps blood throughout the human body. The continuous flow of blood creates a system for vital organs within the body to gain oxygen and nutrients. The timely delivery of oxygen to the body’s organs is very crucial. Brain cells, for example, will die within minutes if the flow of oxygen is obstructed. For the blood to be pumped out of the heart and into the body, contraction of the heart must take place. The rate of contraction is also referred to as the heart rate, which is usually measured in beats per minute. In this experiment, the effect …show more content…
of temperature and chemicals on the heart rate of a Daphnia magna is observed. The heart is readily observed in the experiment because D. magna is transparent. D. magna is ectothermic which means that it gains most of its heat from external sources, such as the environment. These ectotherms are unable to produce enough heat for thermoregulation, so they rely on behavioral means such as seeking out shade or basking in the sun to adjust their body temperature. Due to D. magna’s dependence on temperature, varying temperature can be vital for this animal’s heartbeat (Campbell and Reece, 2009). Temperature can also be related to heartbeat through metabolic rate. Metabolic rate is the total amount of energy an animal uses in a unit of time. Temperature controls metabolism through its effects on the rates of biochemical reactions (Brown et al, 2001). For a chemical reaction to occur, molecules within the body must collide. If the temperature is increased, the movement and collision of particles will increase which will speed up the biochemical reactions. To compensate for this increase in chemical reactions, the heart must pump more nutrients and oxygen throughout the body. As a result, there is an increase in heart rate. The opposite occurs when the temperature decreases because the particles are moving slower, resulting in less chemical reactions (Moore et al, 2008).
Release of chemicals may result in a decrease or increase in chemical reactions, depending on the structure and composition of the chemical.
Acetylcholine is a common neurotransmitter that has an inhibitory effect on vertebrate cardiac muscle. The neurotransmitter does this by releasing neurons which activates a signal transduction pathway. As a result, the G protein in the pathway stops adenylyl cyclase and opens the muscle cell membrane’ potassium channels. These two actions result in a reduction in the cardiac muscle contraction.
Another chemical known as epinephrine has the opposite effect on cardiac muscle. In the wall of the right atrium, there is a cluster of cells called the sinoatrial node that sets the rate for which all cardiac muscle contracts. Hormones, such as epinephrine, within the body can influence the sinoatrial node and cause the heart rate to increase (Campbell and Reese, 2009).
Hypothesis
The Effect of Temperature on the Heart Rate of Daphnia magna
The alternate hypothesis is that the D. magna heart rate will increase as the temperature increases. The D. magna heart rate will decrease as the temperature decreases.
The Effect of Chemicals on the Heart Rate of Daphnia magna
The alternate hypothesis is that Acetylcholine will decrease the heart rate and Adrenaline will increase the heart rate of D. magna.
Materials and …show more content…
Method
The Effect of Temperature on the Heart rate of Daphnia magna A plastic pipette with an enlarged hole made by a cut at the tip was collected along with a depression slide. A small amount of petroleum jelly about the size of a pebble was smeared onto one of the wells. The pipette was then used to draw up a D. magna. After placing the D. magna on the petroleum smeared well, a Kimwipe was used to draw up the culture fluid from the well. The animal was then observed under a dissection microscope to ensure that it was still alive. Two droplets of the culture fluid were then added onto the D. magna to prevent desiccation. The D. magna was then placed onto the dissection microscope and allowed to rest for one minute with the light turned off. The heart was located using the model on the projector. The light was turned on and the number of heart beats was counted for five seconds after allowing the specimen to rest for one minute. This value was recorded and multiplied by 12 to get the number of beats per minute, which provided a room temperature value for the heart rate. The room temperature was determined by exposing the thermometer to the open environment. A glass petri plate was collected and completely filled with ice water. It was placed under the microscope and a thermometer was placed into the ice water until the temperature reached two degrees Celsius. Then, the slide containing the D. magna was placed onto the glass petri plate and allowed to rest for one minute with the light turned off. After the one minute, the light was turned on and the heart beats were counted for five seconds, recorded, and again multiplied by 12 to get the beats per minute. The petri dish was emptied and then filled with cold tap water. A thermometer was placed into the petri dish to determine the temperature, which came out to be 19 degrees Celsius. The same steps were performed to find the beats per minute for the D. magna in the cold tap water. These steps were repeated two more times using warm tap water, which had a temperature of 26 degrees Celsius and hot tap water which had a temperature of 38 degrees Celsius.
The Effect of Chemicals on the Heart Rate of Daphnia magna
A plastic pipette with an enlarged hole, due to a cut at the tip, was collected along with a depression slide. A small amount of petroleum jelly about the size of a pebble was smeared onto one of the wells. The pipette was then used to draw up a D. magna. After placing the D. magna on the petroleum smeared well, a Kimwipe was used to draw off the culture fluid. The animal was then observed under a dissection microscope to ensure that it was still alive. Two droplets of the culture fluid were then added onto the D. magna to prevent desiccation. The D. magna was again placed onto the dissection microscope and allowed to rest for one minute with the light turned off. The heart was located using the model on the projector. After one minute had passed, the light was turned on and the number of beats was counted for five seconds. This value was recorded and then multiplied by 12 to get beats per minute. Using the corner of a Kimwipe, all of the culture fluid was drawn off. Two drops of acetylcholine (concentration 1:10,000) were added onto the D. magna, and it was allowed to rest for one minute. The heart beat was then counted for five seconds and recorded. This value was multiplied by 12 to get beats per minute. The D. magna was allowed to rest for 55 seconds immediately after counting with the light turned off. The step was repeated four more times. After finishing this section, another Kimwipe was used to draw up all of the acetylcholine (concentration 1:10,000) from the well. Two drops of culture fluid were added onto the D. magna and allowed to rest for one minute with the light turned off. The number of heart beats per minute was then calculated by turning the lights on and counting the heart beat for five seconds. This value was then multiplied by 12 and recorded then multiplying that value by 12 and recording it. A Kimwipe was used to draw off all of the culture fluid and two drops of adrenaline (concentration 1:10,000) were then added to the D. magna. After allowing it to rest for one minute with the light turned off, the same steps that were used in the acetylcholine experiment were used to determine the number of beats per minute as a result of the adrenaline. After three minutes however, the D. magna died so the experiment ended.
Results
Temperature and heart rate had a direct relationship. As the temperature increased, the heart rate increased. As temperature decreased, the heart rate also decreased (Figure 1).
Figure 1: Effects of Temperature on Daphnia magna Heart rate
Heart rate increased immediately after the addition of acetylcholine and continued to increase until 3 minutes later. The heart rate began to decrease until minute 4. After 4 minutes, the heart rate was constant (Figure 2).
Figure 2: Effects of Acetylcholine on Daphnia magna Heart rate
Heart rate of D. magna increased for the first minute immediately after the addition of epinephrine. It decreased after the first minute until minute 3. The D. magna died after minute 3 (Figure 3). The chemical epinephrine had a greater increase in number of heart beats than acetylcholine.
Figure 3: Effects of Adrenaline/Epinephrine on Daphnia magna Heart rate
Discussion
The hypothesis for the first experiment involving temperature and heart beat was supported by the results of this study. As the temperature was raised, the rate of heart beat also increased. There was, however, a drop at 26 degrees Celsius. The Daphnia magna has a very quick beating heart, which may have resulted in miscounting if the observer did not pay close enough attention. The direct relationship between the temperature and the heart rate was probably a result of an increase in biochemical reactions (Brown et al, 2001). As temperature increased, particles that were involved moved faster leading to an increase in the likelihood of a collision required for a chemical reaction. The heart rate likely increased because the heart needed to compensate for the increase in chemical reactions by supplying more oxygen and nutrients that are required for metabolic processes. The demand in oxygen and nutrients led to an increase in contraction and therefore in heart rate. The opposite occurred when the temperature was lower because the particles were moving slower. Slower moving particles have a less likely chance of colliding which would decrease the rate of chemical reaction (Moore et al, 2008).
In the second experiment, the result did not support the hypothesis.
The heart rate increased with the addition of acetylcholine whereas acetylcholine was predicted to reduce muscle cell contraction. G proteins in the signal transduction pathway of acetylcholine prevented adenylyl cyclase and the opening of potassium channels which was supposed to reduce cardiac muscle contraction. The light of the dissection microscope may have inhibited this reduction. Every time the light was turned on, its intensity accelerated the heart rate of the D. magna. The D. magna was unable to cope with this light change because it was constantly turned on and off during the experiment. The increase in heart rate may have over-powered the effect of acetylcholine. As a result, the heart rate seemed to increase as an effect of acetylcholine, but in actuality, it was a result of the
light.
The third hypothesis was supported, but it should be noted that epinephrine may induce death. The addition of epinephrine likely influenced the sinoatrial node to increase in the rate and timing of the contraction of cardiac muscle. The heart rate decreased after one minute most likely as a result of the effect of the epinephrine fading away. The death of the D. magna probably occurred because of the rapid change in heart rate (Campbell and Reese, 2009).
Heart related issues have always been a problem within the United States. Due to the importance of the heart, being able to control this phenomenon is vital to maintaining good health. One important component of the heart, the rate of contraction, can be readily controlled. If the heart is contracting abnormally fast, adjusting the temperature within the body to a lower degree or applying the chemical, acetylcholine, may help lower the heart rate. If the heart is beating abnormally slow, using epinephrine or increasing the temperature within the body can help speed up the heart.
Conclusion
1. The heart rate of D. magna gradually increased with the increase in temperature.
2. Acetylcholine increased the heart rate of D. magna.
3. Epinephrine increased heart rate of D. magna. After 3 minutes, the D. magna died.
References
Campbell, Neil., Jane Reece.2009. Biology, 8th ed. Beth Wilbur ed. Benjamin Cummings
Publishing, San Francisco, California. pp.905, 1059-1060.
Moore, John W., Conrad L. Stanitski., Peter C. Jurs. 2008. Chemistry: The Molecular Science,
3rd ed. Lisa Lockwood ed. Lachina Publishing Services, Belmont, California. pp. 645-
650.
Brown, James H., Charnov, Eric L., Gillooly, James F., Savage, Van M., West, Geoffrey B.
2001. Effects of Size and Temperature on Metabolic Rate. pp. 2248-2251
Hieu Duong
6 April 2011
Introduction The heart is a muscular organ that constantly pumps blood throughout the human body. The continuous flow of blood creates a system for vital organs within the body to gain oxygen and nutrients. The timely delivery of oxygen to the body’s organs is very crucial. Brain cells, for example, will die within minutes if the flow of oxygen is obstructed. For the blood to be pumped out of the heart and into the body, contraction of the heart must take place. The rate of contraction is also referred to as the heart rate, which is usually measured in beats per minute. In this experiment, the effect …show more content…
of temperature and chemicals on the heart rate of a Daphnia magna is observed. The heart is readily observed in the experiment because D. magna is transparent. D. magna is ectothermic which means that it gains most of its heat from external sources, such as the environment. These ectotherms are unable to produce enough heat for thermoregulation, so they rely on behavioral means such as seeking out shade or basking in the sun to adjust their body temperature. Due to D. magna’s dependence on temperature, varying temperature can be vital for this animal’s heartbeat (Campbell and Reece, 2009). Temperature can also be related to heartbeat through metabolic rate. Metabolic rate is the total amount of energy an animal uses in a unit of time. Temperature controls metabolism through its effects on the rates of biochemical reactions (Brown et al, 2001). For a chemical reaction to occur, molecules within the body must collide. If the temperature is increased, the movement and collision of particles will increase which will speed up the biochemical reactions. To compensate for this increase in chemical reactions, the heart must pump more nutrients and oxygen throughout the body. As a result, there is an increase in heart rate. The opposite occurs when the temperature decreases because the particles are moving slower, resulting in less chemical reactions (Moore et al, 2008).
Release of chemicals may result in a decrease or increase in chemical reactions, depending on the structure and composition of the chemical.
Acetylcholine is a common neurotransmitter that has an inhibitory effect on vertebrate cardiac muscle. The neurotransmitter does this by releasing neurons which activates a signal transduction pathway. As a result, the G protein in the pathway stops adenylyl cyclase and opens the muscle cell membrane’ potassium channels. These two actions result in a reduction in the cardiac muscle contraction.
Another chemical known as epinephrine has the opposite effect on cardiac muscle. In the wall of the right atrium, there is a cluster of cells called the sinoatrial node that sets the rate for which all cardiac muscle contracts. Hormones, such as epinephrine, within the body can influence the sinoatrial node and cause the heart rate to increase (Campbell and Reese, 2009).
Hypothesis
The Effect of Temperature on the Heart Rate of Daphnia magna
The alternate hypothesis is that the D. magna heart rate will increase as the temperature increases. The D. magna heart rate will decrease as the temperature decreases.
The Effect of Chemicals on the Heart Rate of Daphnia magna
The alternate hypothesis is that Acetylcholine will decrease the heart rate and Adrenaline will increase the heart rate of D. magna.
Materials and …show more content…
Method
The Effect of Temperature on the Heart rate of Daphnia magna A plastic pipette with an enlarged hole made by a cut at the tip was collected along with a depression slide. A small amount of petroleum jelly about the size of a pebble was smeared onto one of the wells. The pipette was then used to draw up a D. magna. After placing the D. magna on the petroleum smeared well, a Kimwipe was used to draw up the culture fluid from the well. The animal was then observed under a dissection microscope to ensure that it was still alive. Two droplets of the culture fluid were then added onto the D. magna to prevent desiccation. The D. magna was then placed onto the dissection microscope and allowed to rest for one minute with the light turned off. The heart was located using the model on the projector. The light was turned on and the number of heart beats was counted for five seconds after allowing the specimen to rest for one minute. This value was recorded and multiplied by 12 to get the number of beats per minute, which provided a room temperature value for the heart rate. The room temperature was determined by exposing the thermometer to the open environment. A glass petri plate was collected and completely filled with ice water. It was placed under the microscope and a thermometer was placed into the ice water until the temperature reached two degrees Celsius. Then, the slide containing the D. magna was placed onto the glass petri plate and allowed to rest for one minute with the light turned off. After the one minute, the light was turned on and the heart beats were counted for five seconds, recorded, and again multiplied by 12 to get the beats per minute. The petri dish was emptied and then filled with cold tap water. A thermometer was placed into the petri dish to determine the temperature, which came out to be 19 degrees Celsius. The same steps were performed to find the beats per minute for the D. magna in the cold tap water. These steps were repeated two more times using warm tap water, which had a temperature of 26 degrees Celsius and hot tap water which had a temperature of 38 degrees Celsius.
The Effect of Chemicals on the Heart Rate of Daphnia magna
A plastic pipette with an enlarged hole, due to a cut at the tip, was collected along with a depression slide. A small amount of petroleum jelly about the size of a pebble was smeared onto one of the wells. The pipette was then used to draw up a D. magna. After placing the D. magna on the petroleum smeared well, a Kimwipe was used to draw off the culture fluid. The animal was then observed under a dissection microscope to ensure that it was still alive. Two droplets of the culture fluid were then added onto the D. magna to prevent desiccation. The D. magna was again placed onto the dissection microscope and allowed to rest for one minute with the light turned off. The heart was located using the model on the projector. After one minute had passed, the light was turned on and the number of beats was counted for five seconds. This value was recorded and then multiplied by 12 to get beats per minute. Using the corner of a Kimwipe, all of the culture fluid was drawn off. Two drops of acetylcholine (concentration 1:10,000) were added onto the D. magna, and it was allowed to rest for one minute. The heart beat was then counted for five seconds and recorded. This value was multiplied by 12 to get beats per minute. The D. magna was allowed to rest for 55 seconds immediately after counting with the light turned off. The step was repeated four more times. After finishing this section, another Kimwipe was used to draw up all of the acetylcholine (concentration 1:10,000) from the well. Two drops of culture fluid were added onto the D. magna and allowed to rest for one minute with the light turned off. The number of heart beats per minute was then calculated by turning the lights on and counting the heart beat for five seconds. This value was then multiplied by 12 and recorded then multiplying that value by 12 and recording it. A Kimwipe was used to draw off all of the culture fluid and two drops of adrenaline (concentration 1:10,000) were then added to the D. magna. After allowing it to rest for one minute with the light turned off, the same steps that were used in the acetylcholine experiment were used to determine the number of beats per minute as a result of the adrenaline. After three minutes however, the D. magna died so the experiment ended.
Results
Temperature and heart rate had a direct relationship. As the temperature increased, the heart rate increased. As temperature decreased, the heart rate also decreased (Figure 1).
Figure 1: Effects of Temperature on Daphnia magna Heart rate
Heart rate increased immediately after the addition of acetylcholine and continued to increase until 3 minutes later. The heart rate began to decrease until minute 4. After 4 minutes, the heart rate was constant (Figure 2).
Figure 2: Effects of Acetylcholine on Daphnia magna Heart rate
Heart rate of D. magna increased for the first minute immediately after the addition of epinephrine. It decreased after the first minute until minute 3. The D. magna died after minute 3 (Figure 3). The chemical epinephrine had a greater increase in number of heart beats than acetylcholine.
Figure 3: Effects of Adrenaline/Epinephrine on Daphnia magna Heart rate
Discussion
The hypothesis for the first experiment involving temperature and heart beat was supported by the results of this study. As the temperature was raised, the rate of heart beat also increased. There was, however, a drop at 26 degrees Celsius. The Daphnia magna has a very quick beating heart, which may have resulted in miscounting if the observer did not pay close enough attention. The direct relationship between the temperature and the heart rate was probably a result of an increase in biochemical reactions (Brown et al, 2001). As temperature increased, particles that were involved moved faster leading to an increase in the likelihood of a collision required for a chemical reaction. The heart rate likely increased because the heart needed to compensate for the increase in chemical reactions by supplying more oxygen and nutrients that are required for metabolic processes. The demand in oxygen and nutrients led to an increase in contraction and therefore in heart rate. The opposite occurred when the temperature was lower because the particles were moving slower. Slower moving particles have a less likely chance of colliding which would decrease the rate of chemical reaction (Moore et al, 2008).
In the second experiment, the result did not support the hypothesis.
The heart rate increased with the addition of acetylcholine whereas acetylcholine was predicted to reduce muscle cell contraction. G proteins in the signal transduction pathway of acetylcholine prevented adenylyl cyclase and the opening of potassium channels which was supposed to reduce cardiac muscle contraction. The light of the dissection microscope may have inhibited this reduction. Every time the light was turned on, its intensity accelerated the heart rate of the D. magna. The D. magna was unable to cope with this light change because it was constantly turned on and off during the experiment. The increase in heart rate may have over-powered the effect of acetylcholine. As a result, the heart rate seemed to increase as an effect of acetylcholine, but in actuality, it was a result of the
light.
The third hypothesis was supported, but it should be noted that epinephrine may induce death. The addition of epinephrine likely influenced the sinoatrial node to increase in the rate and timing of the contraction of cardiac muscle. The heart rate decreased after one minute most likely as a result of the effect of the epinephrine fading away. The death of the D. magna probably occurred because of the rapid change in heart rate (Campbell and Reese, 2009).
Heart related issues have always been a problem within the United States. Due to the importance of the heart, being able to control this phenomenon is vital to maintaining good health. One important component of the heart, the rate of contraction, can be readily controlled. If the heart is contracting abnormally fast, adjusting the temperature within the body to a lower degree or applying the chemical, acetylcholine, may help lower the heart rate. If the heart is beating abnormally slow, using epinephrine or increasing the temperature within the body can help speed up the heart.
Conclusion
1. The heart rate of D. magna gradually increased with the increase in temperature.
2. Acetylcholine increased the heart rate of D. magna.
3. Epinephrine increased heart rate of D. magna. After 3 minutes, the D. magna died.
References
Campbell, Neil., Jane Reece.2009. Biology, 8th ed. Beth Wilbur ed. Benjamin Cummings
Publishing, San Francisco, California. pp.905, 1059-1060.
Moore, John W., Conrad L. Stanitski., Peter C. Jurs. 2008. Chemistry: The Molecular Science,
3rd ed. Lisa Lockwood ed. Lachina Publishing Services, Belmont, California. pp. 645-
650.
Brown, James H., Charnov, Eric L., Gillooly, James F., Savage, Van M., West, Geoffrey B.
2001. Effects of Size and Temperature on Metabolic Rate. pp. 2248-2251