Effect of caffeine on heart rate on Daphina

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Effects of caffeine on the heart rate of daphnia

Aim: to observe the effects of different concentrations of caffeine on the heart rate of daphnia.

Null hypothesis: caffeine has no effect on the heart rate of daphnia.

Alternative hypothesis: as the concentration of caffeine increases so does the heart rate of daphnia.

Scientific background:  

Caffeine is a nerves cell stimulant that increases heart rate by the stimulation of cardiac cells. Caffeine does this by blocking adenosine, a neurotransmitter that allows the body to relax. This blockage results in the adrenal gland to release adrenaline hormone, this causes the heart rate to increase, pupils to dilate, your muscles to tighten up, and glucose is released into the blood stream for extra energy.

Caffeine also increases dopamine; this activates pleasure parts of the brain which activates the caffeine addiction.

Over excess drinking of caffeine could result in restlessness, headaches, and increases blood pressure. Over a long term as the body gets used to the amount of caffeine, it needs higher concentrations for more energy, releasing more and more hormones. This experiment is useful because it proves that caffeine is a stimulant that affects the heart and body, excess drinking of caffeine can be very harmful to the body as it could increase chances of cardiovascular disease.

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Equipment and justification:

Method:

(Control)

  1. Extract the largest daphnia with a pipette out of the beaker and place into a cavity slide.
  2. Absorb all the excess water with a paper towel.
  3. Add a few drops of distilled water along with a few strands of cotton wool into the cavity slide.
  4. Place it under the microscope and count how many times its heart beats in 30 seconds on the stop clock.
  5. When 30 seconds has past, stop the clock and record the heart beats in a table.
  6. Repeat the sample 3 times with distilled water and ...

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