Learn: Core Practical 1 - Caffeine and Daphnia Heart Rate

Welcome!Welcome back! You've already studied the cardiovascular system, including how blood flows through the heart and vessels, and how the cardiac cycle works. Today, we'll be building on that knowledge to investigate the effect of caffeine on heart rate using Daphnia.

Why Daphnia?Daphnia, also known as water fleas, are small aquatic invertebrates. Their heart rate is easy to observe under a microscope, making them ideal for this experiment. By studying their heart rate, scientists can investigate how substances like caffeine affect biological processes.

What is Caffeine?Caffeine is a stimulant found in coffee, tea, and energy drinks. It speeds up the activity of the nervous system and can increase heart rate. Investigating its effects on Daphnia helps us understand how caffeine impacts organisms.

How Does Caffeine Affect Heart Rate?Caffeine stimulates the heart by increasing the release of adrenaline and other chemicals that speed up heart contractions. This can lead to a higher heart rate in both humans and Daphnia.

Ethical ConsiderationsUsing live organisms, like Daphnia, in experiments raises ethical questions. We must minimise harm by handling them carefully and returning them to their environment after the experiment. It's important to consider whether the benefits of the research outweigh the impact on the organisms.

Experimental ProcedureIn this practical, you'll observe the heart rate of Daphnia under a microscope. You'll expose them to different concentrations of caffeine and record the number of beats per minute. It's crucial to handle the Daphnia gently and ensure they remain hydrated.

Review Time!Well done! You've learned about how caffeine affects heart rate, why Daphnia are used, and the ethical considerations involved. Let's test your understanding with a few questions.