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Staying Alive - Human Organs

Grade 3Cambridge (IGCSE)

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

🔑Concepts

•

The human body is organized into systems. For example, the heart and blood vessels make up the circulatory system, while the lungs and windpipe make up the respiratory system.

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Pulse rate is a measurement of how many times the heart beats in one minute. It can be measured at the wrist or neck. During exercise, the heart rate increases to pump more oxygen (O2O_{2}) to the muscles.

📐Formulae

Pulse Rate (BPM)=Number of heartbeatsTime in minutes\text{Pulse Rate (BPM)} = \frac{\text{Number of heartbeats}}{\text{Time in minutes}}

Breathing Rate=Number of breathsTime in minutes\text{Breathing Rate} = \frac{\text{Number of breaths}}{\text{Time in minutes}}

💡Examples

Problem 1:

Sara counted 2222 heartbeats in 1515 seconds. Calculate her heart rate in beats per minute (BPM).

Solution:

To find the BPM, we multiply the 1515-second count by 44 (since 15×4=6015 \times 4 = 60 seconds). BPM=22×4=88\text{BPM} = 22 \times 4 = 88 Sara's heart rate is 8888 BPM.

Explanation:

Heart rate is always measured over a full minute (6060 seconds). Since there are four 1515-second intervals in one minute, we multiply by 44.

Problem 2:

Identify which organ is being described: 'I am located in the chest, protected by the ribcage. I expand when you breathe in and shrink when you breathe out.'

Solution:

The Lungs.

Explanation:

The lungs are the primary organs for gas exchange and are protected by the ribs in the thoracic cavity.

Problem 3:

A student counts their breaths for 22 minutes and records a total of 4040 breaths. What is their breathing rate per minute?

Solution:

Breathing Rate=40 breaths2 minutes=20 breaths per minute\text{Breathing Rate} = \frac{40 \text{ breaths}}{2 \text{ minutes}} = 20 \text{ breaths per minute}

Explanation:

Divide the total number of breaths by the total number of minutes to find the rate for a single minute.