Investigating the effect of chemicals on the rate of heart beat of Daphnia.

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Winston Wong

Investigating the effect of chemicals on the rate of heart beat of Daphnia

Planning

Aim

The aim of the experiment is to look into the effects of the chemicals: ethanol and adrenaline and on the rate of heartbeat of the water flea, Daphnia.

Background Information

Daphnia: A small poikilothermic (body temperature affected by temperature of environment) fresh water crustacean.  It is relatively transparent so its internal organs can be observed though a light microscope, therefore the heartbeat can be seen.

The heart and nerves involved with it: Heartbeats are controlled mainly by nerve pulses. These impulses are caused by pacemaker neurons situated in a group of nerve cells called the cardiac ganglion.  The impulses are then transmitted to larger follower neurons, which carry the signal to the cardiac muscle, causing it to beat.

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Receptors permit communication between neighbouring nerve cells, e.g. between the pacemaker neurons and the follower neurons, the receptors attach to a chemical called a neurotransmitter.  The receptors can accidentally bind onto the other molecules. This can cause an unsuitable change.  

Ethanol: Ethanol is an alcohol and is a depressant; therefore when it attaches to a nerve receptor, rate of heartbeat is most likely to slow down.

Adrenaline: Adrenaline is a hormone produced in the adrenal glands and is a stimulant and is sometimes referred to as the “fight or flight” hormone.  Therefore when it attaches to nerve ...

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