Heart Rate
Biology: Edexcel IGCSE, topic 3.3.23
Heart Rate
Heart rate is the number of time the heart beats per minute. A normal resting heart rate is close to 75 beats per minute. Certain factors can cause an increase in heart rate:
Exercise
- Muscle cells use up more energy (released in respiration) during exercise, so they need to respire at a faster rate.
- The heart pumps faster to circulate oxygenated blood to muscle tissues.
Adrenaline
- In times of fear or stress, adrenaline is a hormone that triggers the so-called ‘fight or flight’ response, preparing the body to move and think quickly in response to danger.
- Adrenaline increases heart rate and blood pressure.
- This means that there is an increase in blood flow around the body, specifically to the muscle cells.