Introduction

Caffeine is an alkaloid compound, which is especially found in the seeds, leaves and fruit of some plants, where it acts as a natural pesticide that kills insects feeding on the plants. Caffeine is part of a group of chemicals called xanthine alkaloids. Xanthine (pronounced /ˈzænθiːn/ or /ˈzænθaɪn/), (3,7-dihydro-purine-2,6-dione), is a purine base found in most human body tissues and fluids and in other organisms. A number of mild stimulants are derived from xanthine, including caffeine and theobromine (2).

Materials and methodsEvery day the subject’s, heart rate and blood pressure (systolic and diastolic) was measured at 8:00, 9:00, 10:00, 11:00, 12:00, 13:00, 15:00. On Monday the subject was given herbal tea (100ml). On Tuesday red bull (100ml). On Wednesday herbal tea (100ml). On Thursday black coffee (100ml of water/ 30g coffee) On Friday water (100ml). The amount of liquid a100ml measuring cylinder was used. The blood pressure was always measured with the subject sitting down, in the classroom and/or the staffroom and was always measured on the left arm. An A&D UA-767 Digital blood pressure monitor was used which measured the heart rate and blood pressure..  

Results

Conclusions

From the graph we can conclude that, when there is a steep rise in the heart rate is due to the Red Bull and the Herbal Tea, whereas when the subject drank coffee, it was constant. However we weren’t expecting these results, as it shows that, our heart rate increases in a steady way when drinking Red Bull, but when you consume coffee, the increase is almost non existent.

Diastolic results show when subject was consuming Red Bull, even though the subject had started at a lower rate, at the end of the day, it had ended at a higher rate than Mondays. On Wednesday, it didn’t show any increase as from the start to the end of the day, it stayed on 64. This could be an anomalous result. On Thursday, when subject consumed coffee, it started at 66.5 and ended at 73 there was a big increase. We could see a correlation between caffeine and increase of diastolic measurement.

Systolic results show that Tuesday it started at a higher rate and ended on a higher rate than Monday. On Wednesday, it started at 121 and ended at 126.5. On Thursday it started at 124.5 and ended at 125.5. This shows us that Thursday showed a more constant increase but Wednesday showed a steeper increase than Thursdays.

Contact/non contact time

Our results show a correlation between contact time and higher systolic measurements. On Monday the range was 107-120 for non contact time, whereas at contact time, it was 124-133. Tuesday, 117-127 non contact, 135.5-137 contact. Wednesday 112-121 in non contact time. contact time,124-137. beginning and end

Investigation into the effect of caffeine on the heart rate

Ravneet Singh , Anisa Shahid, Irshaad Shaikh

Y9 students at Lister Community School

References:

1. Images http://www.chemexper.com/ (accessed 16/03/2014 -19:30)2. http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Xanthine.html (accessed

16/03/2014 -21:00)3. energydrink.redbull.com/caffeine (11th march 3:54)4. http://www.bbc.co.uk/radio1/advice/factfile_az/caffeine (11th march- 6:19 5. BBC bite size (11th march 5:10)6. http://www.medicaldaily.com/why-women-need-more-sleep-men-research-shows-

stronger-mental-physical-response-inadequate-rest (4:00)7. http://sleepfoundation.org/how-sleep-works/how-much-sleep-do-we-really-need (11th

march 2014-16:06)8. Description of products: http://nutritiondata.self.com/(3:30)

Acknowledgements: Miss Scouler (science teacher), Mr Kettle (science teacher), Ms L Green, Ms Quero

(Science teacher).

Fig. 2. Red bull nutrition facts.

Fig. 3 Ecosta Yutu Cuii- organic coffee (Reservas Celulares Forestales, Tutupec Oaxaca

Fig. 4(a-c). Results from heart rate and blood pressure. Trend lines.

(a)(a)

(b)(b)

(c)(c)

Fig. 5. Systolic measurements during contact/non-contact time of teaching..

Fig. 1 Caffeine MoleculeMolecular formula C8H10N4O2 Molecular weight 194.193 mp (°C): 234- 239 (1) .