• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

How does caffeine and ethanol affect the heart rate?

Extracts from this document...


How does caffeine and ethanol affect the heart rate? Introduction At rest a normal adult heart beats around 75 times per minute. During strenuous exercise it may rise to 200 beats per minute. The SAN (sino-atrial node) controls the heart rate. Information is sent via two autonomic nerves that link the SAN with cardiovascular centre in the medulla of the brain, the rate increases or decreases depending on the information received. Factors, which affect the heart: > The secretion of adrenaline. This may be under stress, excitement or other emotions. > Movement of the limbs (exercise). Heart rate and breathing rate increase due to oxygen levels falling and levels of carbon dioxide rising. > Blood pressure. When blood pressure is too high, a mechanism prevents increase in heart rate. Adrenaline is a hormone, which is produced by the adrenal gland; it is usually secreted in tiny amounts, when stressed or scared. It raises your heart rate immediately. Adrenaline improves the strength of the contractions of the heart. ...read more.


The caffeine was inserted into the cavity slide along with the daphnia using a pipette. The caffeine needed to be concentrated in order for the daphnia to survive. Again, the slide was placed under the microscope. The same process as before was carried out to record the number of beats per minute. The concentration of the caffeine used was 1x10 % = 0.00001 The exact same process was used for the ethanol experiment. However, instead of inserting caffeine into the cavity slide, after removing the water, ethanol replaced it. The ethanol also needed to be concentrated and had a concentration of 35%. A concentration of 5% was used, but this proved to be too strong for the daphnia and they died, so 35% seemed to be appropriate. Lab coats were worn throughout the experiment to ensure no substances were spilt over our clothes. After the experiment, hands were washed so that any possible contact from the water(from the daphnia)was washed. Results Original (Daphnia in water) Daphnia Number Reading One Number of beats/min Reading Two Number of beats/min Reading Three Number of beats/min 1 112 132 136 ...read more.


Ethanol: looking at the graphs we can see that ethanol has slowed down the heart rate. In figure 3, it is clear that here is where the widest difference between the original number of beats per minute and the number of beats per minute in ethanol. Crustacean heartbeats are regulated by nerve pulses. The impulses are regulated by pacemaker neurones located in a group of nerve cells called the cardiac Ganglion. Impulses are transferred to larger follower neurones, these carry signals to the cardiac muscle resulting in a heartbeat. For ethanol to decrease the heart rate, it must have some sort of effect on the nerves. When hormones attach to the receptor, the change in the nerve takes place, then the change in the heart rate. Some hormones stimulate an increase and some hormones decrease the heart rate. The nerve fibres conducting pulses to the hearts of daphnia may contain receptors that inappropriately bind to ethanol causing a decrease in the nerve activity. From the above it is possible to say that my hypothesis was correct. Caffeine, being a stimulant, increased the heart rate and ethanol, being a depressant, decreased the heart rate. Melissa Osman 5 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Humans as Organisms section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Humans as Organisms essays

  1. Marked by a teacher

    Does Caffeine Affect Heart Rate?

    4 star(s)

    * Using the same piece of equipment for recording the same for each experiment. * Using the same person to do the recording. * Use the same measurements then it will be fair. SAFETY: The equipment should be used safely so that we can get the right observations.

  2. Marked by a teacher

    Does Caffeine affect Heart Rate?

    3 star(s)

    Effects of caffeine * Boost of energy * A heighten feeling of alertness. * Increases heart rate * Increases in urine * Problems going to sleep * Lack of deep sleep * Jitters * Headaches * Dizziness * Anxiety Amounts of caffeine in food and drink You can see the

  1. Investigation into the factors which affect the heart rate in daphnia.

    Therefore there is less solution for the daphnia to survive as the daphnia is a waterfly which needs water to survive in. This then causes the heartrate to intentionally increase because there is less solution, harder to survive the heart will have to work harder to help the daphnia to survive.

  2. The effect of caffeine concentration on the heart rate of Daphnia.

    I have used the range within the results to place error bars on the chart, as the values I measured are spread about the mean, and as you can see this indicates the variation of results. I could also have used the standard deviation or standard error to quantify the variation.

  1. The heart rate of a Daphnia (water flea)

    224 This proves that my experiment was not nearly accurate enough. This is I think, due to (see Evaluation) Evaluation My procedure worked well and allowed us to collect a sufficient amount of data in support of my predictions. The predictions I made were correct.

  2. Does caffeine affect heart rate

    Using a new daphnia every time (because the previous Daphnia already had a concentration of caffeine in their blood stream, which would affect the results when new concentrations were added), different concentrations of the caffeine solution were tested; we tested a caffeine solution at 40%, 60%, 80% and then 100%.

  1. Effect of Ethanol on the Daphnia heart rate

    The next Petri dish will contain 0.2% ethanol concentration, and you will make concentrations going up to 0.8%, so: * 0.2 %: With the other small syringe (this one will only be used for ethanol), add 2 ml of the 1% Ethanol, to 8 ml of distilled water (remember to use the water syringe).

  2. Investigating The Effect Of Drugs On the Heart Rate of a Daphnia.

    be bigger than another and one may be an adult while another is a child. Also if a daphnia which has been gradually added to more alcohol then its heart rate will hopefully decrease gradually instead of using different daphnia's who's hearts rates will be all different.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work