Does Caffeine Affect Heart Rate?

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Mos

DOES CAFFEINE AFFECT HEART RATE?

AIM:  To investigate the effect of caffeine  on the heart rate of Daphnia (water fleas).

Caffeine is a stimulant drug, which causes increased amounts of stimulatory neurotransmitters to be released.

APPARATUS:  

Culture of Daphnia

Cavity slides and cover slips

Dropping pipettes

Distilled water

Cotton wool

Caffeine solution

Stop clock

Paper towel/ filter paper

Microscope

Lamp

PREDICTION:  I believe that an increase in caffeine concentration in the surrounding water on the daphnia results in an increase in heart rate.

This is known because caffeine is a stimulant, which has the effect, among other things, of increasing the heart rate of any living organism, which consumes or absorbs it.  Caffeine causes increased amounts of stimulatory neurotransmitters to be released.  At high levels of consumption, caffeine has been linked to raised blood pressure and raised heart rate.

A high dosage of caffeine results in an increased neurone firing in the brain.  The pituitary glad sees all the activity and thinks some sort of emergency must be occurring, therefore releasing hormones that tell the adrenal glands to produce adrenaline.  Adrenaline is the ‘fight or flight’ hormone and has a number of effects on your body.  Some of the effects happen to be an in heart BPM (beats per minute), which is an increase in heart rate, and an increase in blood pressure.

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Just like in a human heart, a Daphnia’s heart will beat faster when receiving a dose of caffeine.

METHOD:  A few strands of cotton wool were placed on a cavity slide (helps restrict the movement of the Daphnia).  Using a pipette, one large water flea was transferred to the cavity slide.  Before doing so, the water around the Daphnia was removed using a paper towel.  A few drops of distilled water were added to the cavity slide containing the Daphnia.  A cavity slide filled with iced water was placed under a different slide and was sealed by a ...

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