16. ENVIRONMENTAL AND NUTRITIONAL DISEASES

This chapter explains how the environment and nutrition affect human health. Environmental factors like air pollution and smoking expose the body to harmful chemicals, while nutritional imbalance leads to diseases such as malnutrition, vitamin deficiencies and obesity.

Air Pollution

Air pollution means harmful gases, particles or biological agents present in the air. These pollutants can be natural (volcanoes) or man-made (industries, vehicles).

Types of Air Pollutants

  • Primary pollutants: released directly into the air. Examples: sulfur dioxide (SO₂), nitrogen oxides (NOx), carbon monoxide (CO), particulate matter, volatile organic compounds.
  • Secondary pollutants: formed in the atmosphere when primary pollutants react. Example: ground-level ozone and photochemical smog.

Important Pollutants

  • Sulfur dioxide: irritates eyes and lungs, contributes to acid rain.
  • Nitrogen oxides: involved in smog formation, can cause respiratory irritation.
  • Carbon monoxide: a deadly gas that binds to hemoglobin and causes hypoxia.
  • Particulate matter: causes lung damage and respiratory diseases.
  • Ozone: harmful at ground level, causes throat irritation and breathing difficulty.

Sources

Anthropogenic (human-made): factories, vehicles, burning waste, agriculture, construction, and household chemicals.

Natural sources: volcanoes, dust storms, forest fires, radon gas, methane from animals.

Smoking

1. Industrial Smog

Smog forms when smoke mixes with fog. Burning coal and industrial emissions release sulfur dioxide and nitrogen oxides causing acid rain.

2. Tobacco Smoking

Tobacco smoke contains nicotine, tar and many carcinogens.

  • Nicotine stimulates the nervous system initially but causes dependence.
  • Smoking increases the risk of heart attack, stroke, COPD, and lung cancer.
  • Chronic smokers develop reduced immunity and faster aging of organs.

Protein-Calorie Malnutrition

Occurs when the diet lacks adequate protein and energy. Common in children.

Kwashiorkor

  • Caused by protein deficiency but calories may be adequate.
  • Symptoms: edema, moon face, fatty liver, thin hair, flaky skin, low albumin.

Marasmus

  • Due to severe deficiency of both calories and protein.
  • Symptoms: extreme thinness, muscle wasting, loss of fat, no edema.

Vitamins

Vitamins are essential nutrients required in small amounts. They are of two types:

  • Fat-soluble: Vitamins A, D, E, K
  • Water-soluble: Vitamin B-complex and Vitamin C

Vitamin A

  • Needed for vision, epithelial health and immunity.
  • Deficiency: night blindness, dry skin.
  • Toxicity: headache, nausea, hair loss.

Vitamin B-Complex

Important for energy production and nervous system function.

  • B1 deficiency: beriberi
  • B2 deficiency: cheilosis, glossitis
  • B3 deficiency: pellagra
  • B12/Folic acid deficiency: megaloblastic anemia

Vitamin C

  • Acts as antioxidant, required for collagen synthesis and immunity.
  • Deficiency: scurvy.

Vitamin D

  • Regulates calcium and bone health.
  • Deficiency: rickets in children, osteomalacia in adults.
  • Toxicity: hypercalcemia.

Vitamin K

  • Essential for blood clotting.
  • Deficiency: bleeding disorders.

Vitamin E

  • Antioxidant that protects cell membranes.
  • Deficiency: neuropathy, muscle weakness.

Obesity

Obesity is excess fat accumulation, defined as BMI ≥ 30.

Causes

  • Overeating, lack of physical activity
  • Genetics
  • Hormonal diseases like hypothyroidism or Cushing’s syndrome

Complications

  • Hyperinsulinemia and insulin resistance
  • Type 2 diabetes
  • Hypertension
  • Hyperlipidemia
  • Atherosclerosis and heart attack
  • Fatty liver disease
  • Gallstones
  • Osteoarthritis
  • Higher risk of cancers (breast, colon, prostate)

Starvation

Starvation occurs when the body’s nutritional needs are not met for long periods.

Stages of Starvation

  • First 24 hours: body uses glucose stored as glycogen.
  • Next few days: proteins are broken down to maintain blood glucose.
  • After one week: fat breakdown increases and ketone bodies become major fuel, even for the brain.

Prolonged starvation leads to organ failure and death.

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