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Gallery 7

Heart Rate

A kit drum with a stainless steel handle and green support in front. To the right is a purple infomation sign with the words 'Heart Rate'
A close up of a kit drum.

The rate at which your heart beats can be influenced by events that are exciting or calming.

How it works

Simply grip the silver bar with both hands. Listen to the drum beat in response to your heart rate and see your heart rate as beats per minute on the LCD display.

Things to try or ask around the exhibit

  • Come back and measure your heart rate after trying a scary or energetic exhibit, such as Free Fall!
  • Take deep breaths. How does this affect your heart rate?
  • Will the drum beat faster or slower if you do five star-jumps before holding the bar?
  • Can you hear a change in rhythm if you stand still afterwards?

Background

You can see your heart rate on the LCD display (in beats per minute) and hear the drum beating in time with your heart beat. Sensors inside the exhibit’s bar detect tiny electrical nerve signals being emitted by nerves along your arteries. Your arteries stretch and contract in response to the blood being pushed out by your heart. As the arteries stretch, the nerves are stimulated and they emit tiny electrical signals. The arterial nerve signals are detected by sensors embedded within the bar, which then converts and amplifies the signals via an electronic circuit, to control the LCD display and a stepper motor controlling the drum.

The terms ‘heart rate’ and ‘pulse rate’ are often used interchangeably, although heart rate refers to how often your heart beats, while pulse rate refers to how often your arterial walls are expanding in response to your beating heart pushing blood around your body. The heart generates pressure waves that move the arterial walls. Vasoconstriction means the contraction of blood vessels, while vasodilation means the expansion of blood vessels.

Your actions and environment have a measurable and visible effect on the speed of your heartbeat. Your heart will beat about 100 000 times a day, pushing 7500 litres of oxygen-rich blood through about 96 500 km of branching blood vessels that link our cells together.

Finding the science in your world

When you’re scared or stressed, your body releases more adrenaline (epinephrine). This hormone stimulates nerves, causing your arteries to shrink a little and making your heart beat faster.

When blood vessels constrict they actually increase blood pressure; narrower spaces require more force to push the blood through. However, constricting blood vessels also reduce the amount of blood supplied to tissues, cutting off oxygen and nutrient supply.