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Life Processes and Living Things - The effect of exercise on the heart

Grade 5IGCSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

The heart is a muscular pump that circulates blood through the body to deliver O2O_2 (oxygen) and nutrients to cells.

During exercise, muscles require more energy, which is produced through the process of cellular respiration.

To meet the increased energy demand, the heart must beat faster to deliver more O2O_2 and remove waste products like CO2CO_2 (carbon dioxide).

Pulse rate is a measure of how many times the heart beats in one minute, typically expressed as beats per minute (bpm).

Recovery time is the duration it takes for the heart rate to return to its resting state after physical activity. A shorter recovery time often indicates better cardiovascular fitness.

The resting heart rate for an average 10-year-old is typically between 7070 and 110110 bpm.

📐Formulae

Heart Rate (bpm)=Number of BeatsTime in Minutes\text{Heart Rate (bpm)} = \frac{\text{Number of Beats}}{\text{Time in Minutes}}

BPM=Beats in 15 seconds×4\text{BPM} = \text{Beats in 15 seconds} \times 4

BPM=Beats in 10 seconds×6\text{BPM} = \text{Beats in 10 seconds} \times 6

💡Examples

Problem 1:

Before PE class, Leo measures his pulse and counts 1818 beats in 1515 seconds. After running, he counts 4545 beats in 1515 seconds. Calculate his resting heart rate and his heart rate after exercise in bpm.

Solution:

Resting: 18×4=7218 \times 4 = 72 bpm. After exercise: 45×4=18045 \times 4 = 180 bpm.

Explanation:

To find the beats per minute (bpm) from a 1515-second count, we multiply by 44 because 15 seconds×4=60 seconds15 \text{ seconds} \times 4 = 60 \text{ seconds} (which is 11 minute).

Problem 2:

Why does the body produce more CO2CO_2 during a sprint than while sitting down?

Solution:

During a sprint, muscles perform more respiration to create energy, leading to higher CO2CO_2 production.

Explanation:

Respiration uses O2O_2 and glucose to create energy, releasing CO2CO_2 as a byproduct. Faster movement requires more energy, thus increasing the rate of this chemical reaction.

The effect of exercise on the heart Revision - Grade 5 Science IGCSE