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Health Immunity and Disease - Lifestyle and Autoimmune Diseases

Grade 9IB

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

🔑Concepts

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Lifestyle diseases, also known as non-communicable diseases (NCDs), are conditions primarily caused by the way people live, such as diet, physical inactivity, and substance use. Examples include Type 2 Diabetes and Cardiovascular Disease (CVDCVD).

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Risk factors for lifestyle diseases include high intake of saturated fats and sugars, leading to obesity, which is often measured using the Body Mass Index (BMIBMI).

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Autoimmune diseases occur when the immune system fails to recognize the body's own cells as 'self' and mistakenly attacks them. This is a failure of self-tolerance involving BB-lymphocytes and TT-lymphocytes.

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Type 1 Diabetes is an autoimmune disease where the immune system destroys insulin-producing beta cells in the pancreas, whereas Type 2 Diabetes is a lifestyle disease where cells become resistant to insulin or the pancreas produces insufficient amounts.

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Cardiovascular diseases (CVDCVD) are often linked to atherosclerosis, the buildup of plaques in arteries. This is exacerbated by high blood pressure (hypertension) and high levels of low-density lipoprotein (LDLLDL) cholesterol.

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The 'Hygiene Hypothesis' suggests that a lack of early childhood exposure to infectious agents and microorganisms increases susceptibility to autoimmune diseases by suppressing the natural development of the immune system.

📐Formulae

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

Waist-to-hip ratio=waist circumferencehip circumference\text{Waist-to-hip ratio} = \frac{\text{waist circumference}}{\text{hip circumference}}

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

💡Examples

Problem 1:

An individual has a body mass of 90 kg90\text{ kg} and a height of 1.8 m1.8\text{ m}. Calculate their BMIBMI and determine their weight category if the threshold for 'Obese' is BMI≥30BMI \ge 30.

Solution:

Step 1: Use the formula BMI=massheight2BMI = \frac{\text{mass}}{\text{height}^2}. Step 2: Substitute the values: BMI=901.82BMI = \frac{90}{1.8^2}. Step 3: BMI=903.24≈27.78 kg/m2BMI = \frac{90}{3.24} \approx 27.78\text{ kg/m}^2.

Explanation:

Since 27.78<3027.78 < 30, the individual is classified as 'Overweight' but not yet 'Obese'. However, they are at a higher risk for lifestyle diseases such as Type 2 Diabetes.

Problem 2:

Explain the difference between Type 1 and Type 2 Diabetes in terms of their cause and relationship to lifestyle.

Solution:

Type 1 Diabetes is an autoimmune condition where the body’s immune system destroys the pancreatic cells that produce insulin. Type 2 Diabetes is a lifestyle condition where the body's cells no longer respond correctly to insulin (insulin resistance), often linked to a diet high in C12H22O11C_{12}H_{22}O_{11} (sucrose) and low physical activity.

Explanation:

The primary difference lies in the trigger: Type 1 is an immune system malfunction (non-preventable via lifestyle), while Type 2 is highly correlated with BMIBMI and behavioral choices (largely preventable).