Daphnia Lab Report
HUMAN PHYSIOLOGY REPORT
DAPHNIA
Aim
The aim of this experiment is to investigate the effect of temperature and various substances on the heart beat of Daphnia, a water flea.
Introduction
Daphnia belongs to a group of small, freshwater crustaceans of the order Cladocera commonly called water fleas. They are very suitable for laboratory studies due to the nature of their transparent exoskeletons. Hence, it is possible to watch Daphnia hearts without dissecting them. Daphnia is ectothermic and easily found in pond water which is classified into 80 different species in the UK (J.Parmentier, V.Egmond, 1999 [online]). The anatomy of Daphnia is shown in figure 1 below.
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Figure 2. Photograph of a Daphnia under the …show more content…
Human body temperature is maintained at 37℃ - 38℃ called homeostasis state. As the temperature changes, the human body will react to maintain its homeostasis. When the outside temperature increases, it doesn’t affect the internal environment directly like Daphnia, but indirectly. In a hot environment, the human control centre will send a nerve impulse to expand capillaries to allow more blood to flow near the surface of the body to cool down the body. As there is an increased demand in blood supply, the heart will have to work harder; therefore, beats faster. However, the heart rate will increase for a short time only and become normal as soon as the body temperature is back to normal. In a cold environment, the control centre directs the blood vessels of the skin to constrict to conserve heat. As there is a slower flow of blood, the heart rate is slower as a consequence. Again, as soon as the body temperature rises to normal, the control centre is inactivated. Like Daphnia, human hardly survive in extreme temperature, either very hot or very cold environment. Also, human has a range of heart rate about 60 -110 beats per minute at rest. The human heart cannot beat faster or slower that range for so long; therefore, as the temperature keeps increasing or decreasing, the heart rate stops increasing or decreasing …show more content…
Caffeine is a natural component of coffee which directly involves in causing the increase in Daphnia heart rate after the addition of coffee solution. Caffeine binds to adenosine receptors (adenosine A(1), A(2A) receptors) to prevent adenosine from binding to these receptors of its own. As adenosine is an inhibitory neurotransmitter, this effect of caffeine will prevent the inhibitory effect, and thus increase neural discharge. As a consequent, cardiac muscle will be more active and heart rate will increase (Docshare, 2010 [online]). Likewise, for human, caffeine is a strong stimulant which helps stimulate the nervous system and increase the cell metabolism (M.Kent, 2000). Also, it works by a similar mechanism to Daphnia; it releases the neurotransmitter which makes the heart and breathing rate increase. Therefore, caffeine increases human heart rate as well. However, human has mechanism to alter their enzymes levels to compensate for a higher heart rate, so the effect of coffee (even concentrated) happens only in a short period of
DAPHNIA
Aim
The aim of this experiment is to investigate the effect of temperature and various substances on the heart beat of Daphnia, a water flea.
Introduction
Daphnia belongs to a group of small, freshwater crustaceans of the order Cladocera commonly called water fleas. They are very suitable for laboratory studies due to the nature of their transparent exoskeletons. Hence, it is possible to watch Daphnia hearts without dissecting them. Daphnia is ectothermic and easily found in pond water which is classified into 80 different species in the UK (J.Parmentier, V.Egmond, 1999 [online]). The anatomy of Daphnia is shown in figure 1 below.
68453048260
317190251791
Figure 2. Photograph of a Daphnia under the …show more content…
Human body temperature is maintained at 37℃ - 38℃ called homeostasis state. As the temperature changes, the human body will react to maintain its homeostasis. When the outside temperature increases, it doesn’t affect the internal environment directly like Daphnia, but indirectly. In a hot environment, the human control centre will send a nerve impulse to expand capillaries to allow more blood to flow near the surface of the body to cool down the body. As there is an increased demand in blood supply, the heart will have to work harder; therefore, beats faster. However, the heart rate will increase for a short time only and become normal as soon as the body temperature is back to normal. In a cold environment, the control centre directs the blood vessels of the skin to constrict to conserve heat. As there is a slower flow of blood, the heart rate is slower as a consequence. Again, as soon as the body temperature rises to normal, the control centre is inactivated. Like Daphnia, human hardly survive in extreme temperature, either very hot or very cold environment. Also, human has a range of heart rate about 60 -110 beats per minute at rest. The human heart cannot beat faster or slower that range for so long; therefore, as the temperature keeps increasing or decreasing, the heart rate stops increasing or decreasing …show more content…
Caffeine is a natural component of coffee which directly involves in causing the increase in Daphnia heart rate after the addition of coffee solution. Caffeine binds to adenosine receptors (adenosine A(1), A(2A) receptors) to prevent adenosine from binding to these receptors of its own. As adenosine is an inhibitory neurotransmitter, this effect of caffeine will prevent the inhibitory effect, and thus increase neural discharge. As a consequent, cardiac muscle will be more active and heart rate will increase (Docshare, 2010 [online]). Likewise, for human, caffeine is a strong stimulant which helps stimulate the nervous system and increase the cell metabolism (M.Kent, 2000). Also, it works by a similar mechanism to Daphnia; it releases the neurotransmitter which makes the heart and breathing rate increase. Therefore, caffeine increases human heart rate as well. However, human has mechanism to alter their enzymes levels to compensate for a higher heart rate, so the effect of coffee (even concentrated) happens only in a short period of