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Human Body Systems - Impact of Lifestyle on Health

Grade 7IB

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

🔑Concepts

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The human body requires a balance of nutrients to maintain homeostasis; a lack of essential vitamins or minerals can lead to deficiency diseases, while an excess of C6H12O6C_6H_{12}O_6 (glucose) or fats can lead to type 2 diabetes and obesity.

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Cellular respiration is the process where cells break down C6H12O6C_6H_{12}O_6 in the presence of O2O_2 to release energy (ATPATP), with CO2CO_2 and H2OH_2O as byproducts.

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The circulatory system's efficiency is measured by heart rate (beats per minute, or BPMBPM); regular aerobic exercise strengthens the cardiac muscle, increasing stroke volume and lowering resting heart rate.

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Lifestyle choices like smoking introduce harmful substances such as COCO (carbon monoxide) and tar into the respiratory system, which reduces the surface area of the alveoli and hinders the diffusion of O2O_2 into the bloodstream.

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The Body Mass Index (BMIBMI) is a statistical measurement used to categorize an individual's weight relative to their height, though it does not distinguish between muscle mass and fat mass.

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Excessive consumption of sodium (Na+Na^+) can lead to hypertension (high blood pressure) by increasing the osmotic pressure in the blood vessels, forcing the heart to work harder.

📐Formulae

BMI=mass (kg)height2 (m2)BMI = \frac{mass \text{ (kg)}}{height^2 \text{ (m}^2\text{)}}

C6H12O6+6O2→6CO2+6H2O+Energy (ATP)C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy (ATP)}

Target Heart Rate=(220−age)×% intensity\text{Target Heart Rate} = (220 - \text{age}) \times \text{\% intensity}

Cardiac Output=Stroke Volume×Heart Rate\text{Cardiac Output} = \text{Stroke Volume} \times \text{Heart Rate}

💡Examples

Problem 1:

A 13-year-old student has a mass of 45 kg45\text{ kg} and a height of 1.5 m1.5\text{ m}. Calculate their BMIBMI and determine if they fall within the healthy range (18.518.5 to 24.924.9).

Solution:

BMI=451.52=452.25=20 kg/m2BMI = \frac{45}{1.5^2} = \frac{45}{2.25} = 20\text{ kg/m}^2

Explanation:

Since 20 kg/m220\text{ kg/m}^2 is between 18.518.5 and 24.924.9, the student is within the healthy weight range for their height.

Problem 2:

During exercise, a student's heart rate increases from 70 BPM70\text{ BPM} to 140 BPM140\text{ BPM}. If their stroke volume is 70 mL70\text{ mL} per beat, calculate the change in Cardiac Output in Liters per minute (L/minL/min).

Solution:

Resting Output=70×70=4900 mL/min=4.9 L/min\text{Resting Output} = 70 \times 70 = 4900\text{ mL/min} = 4.9\text{ L/min} Exercise Output=140×70=9800 mL/min=9.8 L/min\text{Exercise Output} = 140 \times 70 = 9800\text{ mL/min} = 9.8\text{ L/min} ΔOutput=9.8−4.9=4.9 L/min\Delta \text{Output} = 9.8 - 4.9 = 4.9\text{ L/min}

Explanation:

Cardiac output is the volume of blood pumped by the heart per minute. Exercise doubles the heart rate in this scenario, thereby doubling the total volume of oxygenated blood delivered to the muscles.

Problem 3:

Explain the chemical impact of Carbon Monoxide (COCO) from cigarette smoke on the blood's ability to transport O2O_2.

Solution:

COCO has a higher affinity for hemoglobin than O2O_2. It forms carboxyhemoglobin (HbCOHbCO) instead of oxyhemoglobin (HbO2HbO_2).

Explanation:

Because COCO binds more tightly to hemoglobin, it prevents O2O_2 from attaching to red blood cells. This reduces the amount of O2O_2 available for cellular respiration, causing the heart to pump faster to compensate.

Impact of Lifestyle on Health - Revision Notes & Key Formulas | IB Grade 7 Science