Heart Rate & Exercise (Edexcel IGCSE Science (Double Award)) : Revision Note

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Heart Rate & Exercise

Control of the heart rate

  • A heart rate is measured by counting the number of times a heart beats in a minute (bpm)

    • Factors such as exercise or levels of adrenaline can affect a heart rate

  • The natural resting heart rate is controlled by a group of cells located in the right atrium called the pacemaker

    • The role of the pacemaker is to coordinate the contraction of the heart muscle and regulate the heart rate

    • Pacemaker cells send out electrical impulses which initiate a contraction in the cardiac muscle

Exercise and heart rate

  • The heart pumps blood to respiring cells to supply oxygen and glucose and remove respiratory waste

  • During exercise, muscle cells respire faster to increase energy supply

    • Respiration is aerobic during moderate exercise and anaerobic during intense exercise

  • Increased respiration raises the need for oxygen, glucose, and waste removal

  • The nervous system responds by:

    • Increasing heart rate to deliver oxygen and glucose more frequently

    • Increasing the volume of blood pumped to supply larger amounts of oxygen and glucose

  • At the end of a period of exercise, the heart rate may remain high for a period of time as oxygen is required in the muscles to break down the lactic acid from anaerobic respiration

  • Production of the hormone adrenaline also increases heart rate as part of a 'fight or flight' response

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Lára Marie McIvor

Author: Lára Marie McIvor

Expertise: Biology, Psychology & Sociology Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.

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