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TITLE: THE EFFECT OF CAFFEINE ON HEART RATE

NAME: NUR AMALINA BT ZOLKEFLEE

SID NUMBER: 2010843164

CLASS: 11M2

DATE OF EXPERIMENT: 16TH AUGUST 2010

LECTURER’S NAME: DR.NORAINI BINTI FADZILLAH

PARTNER’S NAME: FATIN NABILAH BT MOHD NASIR

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ABSTRACT

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INTRODUCTION

BACKGROUND INFORMATION

Human have consumed caffeine since Stone Age. Early people found that eating seed,

bark, and leaves of certain plants had increase their awareness, decrease their fatigue and

stimulate their mood. So what is actually caffeine ? Caffeine is a white crystalline

xanthine alkaloid, a phsychoactive stimulant drug. It is discovered by a German chemist,

Friedrich Ferdinand Runge in 1819. Caffeine can be found in beans, leaves and fruit of

some plants where it acts as natural pesticide that paralyse and kill certain insects feeding

on the plants. Caffeine is also consumed by human in infusions extracted from bean of

coffee plants and leaves of tea bush. In humans, caffeine is said to give a big impact on

human central nervous system(CNS). It is said can ward off drowsiness, restore alertness,

and has diuretic( a substance that cause increase in flow of urine) properties. But studies

did not show that caffeine can cause dehydration because most regular caffeine

consumers had developed a very strong tolerance in it. Basically, the normal function of

caffeine is it act as natural pesticide and inhibit seed germination of nearby coffee

seedlings, giving it a better chance of survival. The common source of caffeine is tea,

coffee and chocolate derived from cocoa bean. Caffeine content in coffee varies

depending on type of coffee bean and method used to derive the caffeine. But in general,

in 30ml of espresso, there are 40mg of caffeine, in 120ml of drip coffee, there are 100mg

of caffeine. Factually, dark-roast coffee has less caffeine than the lighter roast because

roasting process reduce the bean’s caffeine content.Is it true tea has more caffeine than

coffee? Well, although tea contains more caffeine than coffee (by dry weight), a typical

serving contains is less, as tea is normally brewed much weaker. Besides strength of the

brew, growing conditions, processing techniques and other variables also affect caffeine

content. Certain types of tea may contain somewhat more caffeine than other teas. Tea

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contains small amounts of theobromine and slightly higher levels of theophylline than

coffee. Recently, many manufacturers begun putting caffeine in their products especially

the shower products like shampoo and soap. Studies show that caffeine in shampoo

applied for two minutes is absorbed through the skin and reaches blood stream. They

claimed it can improve mental alertness. Caffeine is being used pharmacologically in

order to treat apnea in premature newborns. In 1819, Ferdinand isolated relatively pure

caffeine for the first time..

Diagram 1.1 shows the caffeine.

The nitrogen atoms which are planar( sp2 orbital hybridization) in caffeine resulting

caffeine’s molecule having aromatic character. Moving to effect of caffeine on human’s

body. As a CNS and metabolic stimulant, it helps to reduce fatigue and restore mental

alertness. It also helps in correcting irregular heart beats, make it faster and clearer flow

of thought, increase our focus, improve body coordination and act as competitive

inhibitor to adenosine, a neurotransmitter. Caffeine from coffee is absorbed by stomach

and small intestine within 45 minutes and then distributed to all body tissues. If we take

caffeine in moderation, it take less than hour for caffeine to begin affecting the body and

it will be ergogenic (increase a person’s ability for mental and physical labour) to us. A

study carried out show that trained runners showed 44% increase ‘race-pace’ endurance

as well as a 51% increase in cycling endurance, after a dosage of 9 milligrams of caffeine

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per kilogram of body weight. Caffeine will also increase the effectiveness of drug. For an

example, it makes pain reliever 40% more effective in relieving headache if being taken

with caffeine. Nowadays, more and more headache drugs include caffeine in their

formulae. But, there’s still bad effect if we take it excessively. This can lead to

caffeinism. Caffenism together with caffeine dependency can cause nervousness, anxiety,

irritability, muscle twitching, insomnia, headaches, heart palpitation and peptic ulcers. In

heart, caffeine bind to receptors on surface of heart muscle cells, which leads to an

increase in the level of cAMP ( cyclicAMP- function to increase activity of funny current

which directly increase the heart rate) inside the cells by blocking the enzyme that

degrades cAMP and mimicking the effects of epinephrine (which binds to receptors on

the cell that activate cAMP production). cAMP acts as a "second messenger," and

activates a large number of protein kinase A (PKA~cAMP-dependent protein kinase).

This has the overall effect of increasing the rate of glycolysis and increases the amount of

ATP available for muscle contraction and relaxation. According to one study, caffeine in

the form of coffee helps to reduce the risk of heart disease. However, the protective effect

was found only in participants who were not severely hypertensive ( patients that are not

suffering from a very high blood pressure). Research suggests that drinking caffeinated

coffee can cause a temporary increase in the stiffening of arterial walls. In order to

determine effect of caffeine in human life, we have to take a substitute of human being.

Daphnia has been chosen because it have sort of heart that we can see in magnification

due to its transparent body. Daphnia or commonly known as water flea is a small,

planktonic crustaceans. It is 0.2~0.5mm in length which can been seen by naked eyes. It

live in various aquatic environment from acidic swamps to freshwater lakes, ponds,

streams and rivers.

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Diagram 1.2 shows daphnia and where the heart locate.

In many Daphnia species, the skin is translucent. Therefore, it is an excellent subject as

one can observe the beating heart on top of the back, just behind the head. Average heart

rate for Daphnia is 180 beats per minute(BPM). Daphnia is prone to alcohol intoxication,

and therefore making it a good subject to study the effect of depressant on nervous

system. Not only alcohol, Daphnia can also become an indicator to study the effect of

caffeine, nicotine and adrenaline on heart beat. Daphnia is belong to clodoceran family

Daphiniidae. It reproduce parthenogetically usually in spring until end of summer. The

newly hatched Daphnia must moult several times before they are fully grown into an

adult usually after about two weeks. The young are small copies of the adult; there are no

true nymphal or instar stages. A fully mature female able to produce young about every

10 days under normal condition. The Daphnia’s lifespan are not more than 1 year.

Usually 108 days at 30C while 29 days at 280C. They eat tiny crustaceans but usually

ingest unicellular algae, protists, bacteria, and yeast(normally in lab). The beating of legs

produces a constant current through the skin which bring the material into digestive tract.

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The trapped food particles are formed into food bolus. The food bolus moves down the

digestive tract until is emptied through the anus. Basically, Daphnia is being used to test

the effect of toxins on ecosystem also known as indicator species. This is due to their

short lifespan and reproductive capabilities. In order to count the heart beat of Daphnia,

we need to use a microscope ; either compound microscope with low power objective or

dissecting microscope. A depression slide is used instead of plain slide. This is due to the

depression slide have polished, concave depression at the centre of slide where it can hold

large drop of water.

Diagram 1.3 shows microscope Light source, a light or a mirror (7) Diaphragm and condenser lens (8) Objective (3)

Ocular lens (eyepiece) (1) Objective turret (to hold multiple objective lenses) (2) Stage (to hold the sample) (9) Focus wheel to move the stage (4 - coarse adjustment, 5 - fine adjustment)

RATIONALE OF REPORT

Nowadays, due to the fast developing world, people tend not to care about the food or

the beverages the take each day. As long as it tastes nice then everyone would prefer to

have it. Did you ever know that the drink that we often have during our breakfast is an

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insecticide? Sounds horrible right? Yeah, caffeine acts as natural insecticide to the plants

it comes from. It can paralyse or even kill the insects feeding on its leaves, barks, fruits

etc. Cocoa in South Africa, and tea in Asia have all been used for hundred years to

produce drinks containing caffeine. Even these days, caffeine is also used as flavour

enhancer in soft drinks. In humans, caffeine acts as a stimulant drug, causing increased

amounts of stimulatory neurotransmitters to be released. At high levels of consumption

caffeine has been linked to restlessness, insomnia, and anxiety, causing raised blood

pressure. This can lead to heart and circulation problems. That is why it is important for

us to carry out this experiment. To see by ourselves how the heart beat increase when the

Daphnia is put into caffeine of 0.5% concentration. From this experiment, we can analyse

the data and use it to compare with human being, But we have to be careful because

Daphnia is different from human. Things happen to Daphnia might not be the same as

taken place in human being.

OBJECTIVES

Basically, our experiment is done to investigate the effect of caffeine on heart rate of

Daphnia. This experiment also is done to find the average heart beat of Daphnia at

normal condition( without being caffeinated) . Next, we would like to create awareness

among society how caffeine give such great impact on our heart. It can lead to

cardiovascular diseases because as our heart rate increase, this will at the same time

increase our blood pressure and thus give tense to our arteries, which is very harmful. By

measuring the heart rate of Daphnia in normal condition and caffeinated condition, we

can compare the heart rate and thus making it as an indicator for human heart rate.

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EXPERIMENTAL HYPOTHESIS

Presence of caffeine on Daphnia will increase the heart rate. This is because caffeine

is a stimulant. It means that it will increase the heart rate of living organism which

consume or absorb it( For this case, Daphnia absorb). At very high consumption, caffeine

linked to raised blood pressure. As blood pressure increase, the alertness (which is linked

to neurones in brain) also increase. The stimulated pituitary gland in brain send impulse

to adrenal gland to release adrenaline( a fight or flight hormone). This hormone

eventually increase the heart rate. That is how caffeine can increase our heart rate.

NULL HYPOTHESIS

There is no difference in rate of heart beat between Daphnia in culture solution and

caffeine solution. This is because Daphnia is highly resistant to caffeine. Furthermore,

caffeine does not affect anything to Daphnia’s body meaning that it will not affect human

body too.

VARIABLES

MANIPULATED VARIABLE: Presence of caffeine in solution where Daphnia is put in

CONSTANT VARIABLE: Species of Daphnia

RESPONDING VARIABLE: Heart beat per minute(BPM)

MATERIALS AND APPARATUS

MATERIALS: Culture of Daphnia, 0.5% caffeine solution, tissue paper, muslin cloth,

paper.

APPARATUS : plastic transfer pipette, beaker, stopwatch, compound microscope, pencil,

dissecting slide,

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METHOD

Measuring normal heart rate of Daphnia1. By using a plastic pipette, a Daphnia is withdrawn from the beaker

containing culture solution.

2. The Daphnia is placed on the cavity slide together with a few drops of

pond water( culture solution).

3. Excess pond water is wiped using muslin cloth.

4. By using a microscope , the Daphnia is focussed under the low-powered

objective lens. Then, the heart is focussed.

5. The heart rate is counted by tapping a piece of scrap paper eveytime the

heart beats and marks are counted afterwards. The heart rate is counted for

20 seconds. The count is repeated three times to get the average value.

6. Values are times with three to get the heart beat per minute.

7. Readings are recorded and tabulated.

Mesuring the heart rate of Daphnia in caffeine solution

1. The culture solution is drew off. By using a dropper, a drop of

caffeine solution is added onto the Daphnia.

2. By using a microscope , the Daphnia is focussed under the low-

powered objective lens. Then, the heart is focussed.

3. The heart rate is counted by tapping a piece of scrap paper

eveytime the heart beats and marks are counted afterwards. The

heart rate is counted for 20 seconds. The count is repeated three

times to get the average value.

4. Values are times with three to get the heart beat per minute.

5. Readings are recorded and tabulated

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SAFETY MEASURES AND RISK ASSESSMENT

There are a few safety measures that must be taken into consideration in order to make

sure that the experiment is going on smoothly without any accidents. But this experiment

is quite simple because it does not involve hazardous substances. The materials used are

apparently not harmful but still there are a number of safety measures that we must obey.

First, we must wear the lab coat to prevent any stain onto our cloth. We have to make

sure the concentration of caffeine used is not more than 1% because Daphnia does not get

enough oxygen in such concentrated solution. Do not eat and drink throughout the

experiment because the biology lab still keep the hazardous chemical substances even we

are not using it. We must also be very careful when handling the lab apparatus like

beakers and cavity slide which tend to break easily and will harm our safety. The

microscope are fragile and light bulbs can get so hot, so we have to be careful. We have

to take care of handling any chemicals that might be affected the heart rate of Daphnia.

And always keep the laboratory in clean state.

RESULTS AND DATA

Table 1: Daphnia in culture solution(normal condition)

Heart rate of Daphnia in

20s

Heart rate of Daphnia in one minute

10 30

9 27

8 24

Therefore, the average value of Daphnia’s heart rate= (30+27+24)/3

= 27 BPM

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Table 2: Daphnia in 0.5% caffeine solution

Heart rate of Daphnia in

20s

Heart rate of Daphnia in one minute

14 42

12 36

11 33

Therefore, the average value of Daphnia’s heart rate= (42+36+33)/3

= 37 BPM

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DISCUSSION

Based on our result, we found that the heart rate of Daphnia increase when it is put

in caffeine solution. In normal condition, the heart rate of Daphnia is 27 beats per minute,

while in caffeine solution, it is 37 beats per minute.The heart rate increase by 37%. Our

result meets our hypothesis. Caffeine solution is indeed a stimulant. Upon comparing our

result with other groups, they got the same as us that is an increment in heart rate in

caffeine solution. As we look on the sequence of our result, the heart rate decrease with

time, means that the first data is higher than the second, and so did the second data, it is

higher than the third one making the first data to be the highest and the last data is the

lowest. We conclude that as time goes on, the Daphnia is stressful enough to be in little

of water. It is dying actually.

CONCLUSION

After we have done this experiment, finally we came into conclusion heart rate of

Daphnia do increase in caffeine solution compared to its normal heart rate. Our

experimental hypothesis is accepted. The heart rate increase by 37% is because caffeine is

a stimulant. Caffeine belong to a group of compound called methylxanthines which affect

the heart rate by increasing beats per minute. It blocks adenosine receptor on surface of

heart muscle which produce adenosine(function to slow down heart rate in human causing

sleepiness). If this receptor is blocked, then fewer enzyme is produced and hence making

the heart rate increase. Daphnia is an unique organism because it absorbs chemicals that

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are present in the water surround it without selection. We conclude that our experiment

is successful because all the objectives aimed before experiment have been achieved.

LIMITATIONS AND ANOMALAOUS RESULT

There are a few limitations that prevent us from getting a very acurate and precise

result.This is due to lack in time. Most of our time is wasted to catch the tiny Daphnia in

pond water. It is so hard to see such small creature with naked eyes. We are also lack in

Daphnia which only 2 Daphnia provided for us. This is because Daphnia has short

lifespan. They died easily.. The actual value for Daphnia’s normal heart rate is 172 beats

per minute, but ours is only 27 beats per minute. While for in caffeine,it is 173 BPM, but

ours is 37 BPM only. We conclude that measurement that we took is not accurate due to

Daphnia become stressed in small volume of water. Therefore, the heart beats irregularly

and the measurements taken is not accurate enough. The illuminating light from

microscope have create a high temperature surrounding which is not suitable for Daphnia,

a temperature-sensitive organism. While taking the measurements, the Daphnia keep

moving and swimming around. With the beating leg and its active movement are

confusing us to see the heart beats

SUGGESTION FOR IMPROVEMENT

In order to get a more accurate result, a few suggestions had came across. The first one

is instead of using a plastic pipette to withdraw the Daphnia, it is better for us to use a

small fishing net. Using pipette took a lot of time because we tend to catch the

algae(bigger in size) rather than Daphnia which is small and transparent. The experiments

also should be repeated thoroughly (from beginning till end) to get a more valid result.

When the Daphnia moves around, we should wipe the solution so that it is hard for it to

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swim around with much less solution. To prevent the Daphnia from overheating, while

observing the heart rate, we should turn off the microscope and use the heat sink- a cavity

slide filled with iced-water was placed under different slide and was sealed by a

coverslip. This slide was then placed below the slide containing Daphnia.

REFERENCES AND BIBLIOGRAPHY

http://www.naturalhub.com/natural_food_guide_fruit_vitamin_c.htm; 4th August 2010

http://en.wikipedia.org/wiki/Vitamin_C; 4th August 2010 http://www.practicalbiology.org/areas/advanced/health-and-disease/whats-in-our-

food/measuring-the-vitamin-c-content-of-foods-and-fruit-juices,53,EXP.html; 4th August 2010

http://www.coursework.info/GCSE/Biology/Living_Things_in_their_Environment/Measurement_of_the_vitamin_C_content_of_L10763.html; 4th August 2010

http://en.wikipedia.org/wiki/Dichlorophenolindophenol; 4th August 2010

APPENDIX

Scientific classification Kingdom: AnimaliaPhylum: ArthropodaSubphylum: CrustaceaClass: BranchiopodaOrder: CladoceraFamily: DaphniidaeGenus: DaphniaMüller, 1785 Species

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Subgenus Daphnia

D. ambiguaD. arenata

D. catawba

D. cheraphila

D. latispina

D. melanica

D. middendorffiana

D. minnehaha

D. neo-obtusa

D. obtusa

D. oregonensis

D. parvula

D. pileata

D. prolata

D. pulex

D. pulicaria

D. retrocurva

D. tanakai

D. tenebrosa

D. villosa

Subgenus Hyalodaphnia

D. curvirostrisD. dentifera

D. dubia

D. galeata

D. lacustris

D. laevis

D. longiremis

D. longispina

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D. mendotae

D. thorata

D. umbra

Subgenus Ctenodaphnia

D. barbataD. brooksi

D. ephemeralis

D. exilis

D. lumholtzi

D. magna

D. salina

D. similis

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