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Living Things - Human Body Systems (Circulatory, Respiratory, Digestive)

Grade 5IB

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

🔑Concepts

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The Digestive System is responsible for breaking down food into nutrients such as glucose (C6H12O6C_6H_{12}O_6). This involves mechanical digestion (teeth) and chemical digestion (enzymes and stomach acid).

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The Respiratory System facilitates gas exchange. In the lungs, oxygen (O2O_2) is absorbed into the bloodstream at the alveoli, while carbon dioxide (CO2CO_2) is released from the blood to be exhaled.

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The Circulatory System acts as the body's transport network. The heart pumps blood containing O2O_2 and nutrients to the body's cells and carries CO2CO_2 and waste products away.

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Interaction of Systems: The Digestive system provides the fuel (C6H12O6C_6H_{12}O_6), the Respiratory system provides the catalyst (O2O_2), and the Circulatory system delivers both to cells to produce energy through cellular respiration.

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Blood Vessels: Arteries carry oxygenated blood away from the heart (high O2O_2 concentration), while veins carry deoxygenated blood back to the heart (high CO2CO_2 concentration), except in pulmonary circulation.

📐Formulae

C6H12O6+6O2→6CO2+6H2O+EnergyC_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}

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

Total Lung Capacity=Vital Capacity+Residual Volume\text{Total Lung Capacity} = \text{Vital Capacity} + \text{Residual Volume}

💡Examples

Problem 1:

During a science experiment, a Grade 5 student measures their pulse and counts 2020 beats in 1515 seconds. Calculate the student's heart rate in Beats Per Minute (BPM).

Solution:

20×4=80 BPM20 \times 4 = 80 \text{ BPM}

Explanation:

To find the heart rate for a full minute (6060 seconds), you multiply the count from 1515 seconds by 44, because 15×4=6015 \times 4 = 60.

Problem 2:

Describe the change in gas concentration as blood passes through the capillaries surrounding the alveoli in the lungs.

Solution:

The concentration of O2O_2 increases while the concentration of CO2CO_2 decreases.

Explanation:

Due to diffusion, oxygen moves from the high-concentration area in the alveoli to the lower concentration in the blood, while CO2CO_2 moves from the blood into the lungs to be exhaled.

Problem 3:

Which system is primarily responsible for the transport of C6H12O6C_6H_{12}O_6 to the muscles during exercise?

Solution:

The Circulatory System.

Explanation:

While the Digestive system extracts the glucose (C6H12O6C_6H_{12}O_6) from food, the Circulatory system (via blood plasma) is responsible for moving it to the muscle cells.

Human Body Systems (Circulatory, Respiratory, Digestive) Revision - Grade 5 Science IB