Chapter 2: Health and Diseases
Comprehensive chapter summary with detailed explanations and examples.
Grade 8 Chapter 2: Health and Diseases
Introduction
Health is a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity. Disease, on the other hand, is a condition of the body or mind that disturbs the normal functioning of an organism. This chapter explores various types of diseases, their causes, symptoms, and methods of prevention and treatment, emphasizing the importance of public health and healthy lifestyle choices.
Types of Diseases
Diseases can be broadly classified into two main types:
- Infectious Diseases: Diseases spread through pathogens (microorganisms like bacteria, viruses, fungi, protozoa).
- Non-infectious Diseases: Diseases that do not spread through pathogens, often caused by lifestyle, genetics, or environmental factors.
Infectious Diseases
These diseases spread from one person to another through various means. Maintaining hygiene and public sanitation is crucial to prevent their spread.
Common Infectious Diseases and Their Details
| Disease | Pathogen | Mode of Infection | Symptoms | Prevention and Treatment |
|---|---|---|---|---|
| Tuberculosis (TB) | Bacteria (*Mycobacterium tuberculosis*) | Spitting by patient, air (through coughing/sneezing), prolonged contact with patient, sharing materials. | Chronic cough, blood in sputum, difficulty breathing, weight loss, fever, chest pain. | BCG vaccination, isolation of patients, regular medication (DOTS). |
| Hepatitis | Virus (Hepatitis A, B, C, D, E) | Contaminated water/food (A, E), blood transfusion, shared needles, unprotected sexual contact (B, C, D). | Anorexia, yellow urine, general weakness, nausea, vomiting, grey stools. | Boiled water, proper storage of food, vaccination (for A, B). |
| Dysentery | Bacteria (*Shigella*, *E. coli*), Virus, Protozoa (*Entamoeba histolytica*) | Contaminated food/water. | Watery stools, pain in abdomen, fever. | Clean food and water, ORS. |
| Typhoid | Bacteria (*Salmonella typhi*) | Contaminated food/water. | Anorexia, headache, rash, high fever (104°F), abdominal pain. | Clean food and water, vaccination. |
| Cholera | Bacteria (*Vibrio cholerae*) | Contaminated food/water. | Vomiting, severe diarrhea, dehydration, muscle cramps. | Clean food and water, vaccination. |
| Malaria | Protozoa (*Plasmodium* species) | Female Anopheles mosquito bite. | Recurrent fever with shivering, headache, vomiting, sweating. | Prevent mosquito breeding (no stagnant water), mosquito nets, repellents, antimalarial drugs. |
| Dengue | Virus (DENV) | Female Aedes aegypti mosquito bite. | Acute fever, headache, vomiting, pain in eye sockets, decreased platelet count (can lead to internal hemorrhage). | Prevent mosquito breeding (clean surroundings, no stagnant water), mosquito nets, repellents. |
Other Infectious Diseases
Swine Flu
Pathogen: H1N1 virus. This virus spreads through the nose, throat, and lungs of people, and also through pigs.
Mode of Infection: Spread through contact with infected pigs or humans, and through droplets from coughing and sneezing.
Symptoms: Difficulty in breathing, sore throat, body pain, fever.
Prevention and Treatment: Avoid contact with infected persons, maintain hygiene, prompt medical attention.
AIDS (Acquired Immuno Deficiency Syndrome)
Pathogen: HIV (Human Immunodeficiency Virus). This virus destroys the body's immune system.
Mode of Infection:
- Unprotected sexual contact.
- Through blood transfusion (infected blood).
- Sharing of needles/syringes.
- From infected mother to baby during pregnancy, birth, or breastfeeding.
Symptoms: HIV infection does not show immediate symptoms. Symptoms appear after 8-10 years. These include persistent fever, weight loss, chronic diarrhea, skin rashes, and opportunistic infections.
Diagnosis: ELISA test, Western Blot test.
Prevention: Safe sexual practices, screening of blood before transfusion, use of sterilized needles/syringes, avoiding sharing personal items that might come into contact with blood.
Rabies
Pathogen: Rabies virus.
Mode of Infection: Bite of infected animals (dogs, rabbits, monkeys, cats, bats). The virus enters the brain via nerves.
Symptoms: Fever for 2-12 weeks, hydrophobia (extreme fear of water), exaggerated behavior, hallucinations, paralysis. Fatal disease.
Prevention and Treatment: Immediate vaccination after animal bite (5 doses), washing the wound thoroughly with soap and water. Vaccination is crucial for prevention.
Non-infectious Diseases
These diseases do not spread from one person to another. They are often caused by internal factors or lifestyle choices.
1. Cancer
Definition: Uncontrolled and abnormal cell growth in any part of the body, leading to the formation of malignant tumors or lumps. Cancer cells often spread to other parts of the body (metastasis).
Causes:
- Consumption of tobacco (smoking, chewing).
- Alcoholism.
- Lack of fiber in diet (fruits, leafy vegetables).
- Excessive consumption of junk food.
- Obesity.
- Lack of physical exercise.
- Heredity (genetic predisposition).
Symptoms: Chronic cough, hoarse voice, difficulty swallowing, unexplained lumps, unexplained weight loss, chronic fever, persistent headache, change in bowel habits, abnormal bleeding.
Types of Cancer: Oral cancer, breast cancer, blood cancer (leukemia), lung cancer, stomach cancer, skin cancer, etc.
Prevention and Treatment: Avoid tobacco and alcohol, balanced diet, regular exercise, early detection, chemotherapy, radiation therapy, surgery.
2. Diabetes
Definition: A condition where the body either does not produce enough insulin or cannot effectively use the insulin it produces, leading to high blood sugar levels. Insulin is a hormone produced by the pancreas that regulates blood sugar.
Causes:
- Heredity (genetic predisposition).
- Obesity.
- Lack of physical exercise.
- Mental stress.
- Excessive consumption of sugar, refined carbohydrates, and junk food.
Symptoms: Frequent urination at night, increased thirst, increased hunger, weight loss, blurred vision, fatigue, slow healing of wounds.
Prevention and Treatment: Balanced diet, regular exercise, medication (insulin injections or oral drugs), avoiding sugary foods.
3. Heart Diseases (Heart Attack)
Definition: A condition where the heart muscles do not receive sufficient blood supply due to decreased efficiency of the heart's pumping action. This can be caused by blockages in the coronary arteries.
Causes:
- Smoking.
- Alcoholism.
- Diabetes.
- Obesity.
- Lack of physical exercise.
- Mental stress.
- Heredity.
- High blood pressure, high cholesterol.
Symptoms: Severe chest pain, pain in shoulders, neck, and arms, cramps in hands, tremors, breathlessness, sweating, uneasiness.
Prevention and Treatment: Balanced diet, regular exercise, stress management, avoiding smoking and alcohol, medical treatments like angioplasty, bypass surgery, pacemaker insertion, or heart transplant.
Misuse of Medicines
Antibiotics
Definition: Antibiotics are medicines used to cure bacterial infections. They work by killing or inhibiting the growth of bacteria.
Misuse:
- Taking antibiotics without a doctor's prescription.
- Taking antibiotics for viral infections (e.g., flu, common cold), against which they are ineffective.
- Stopping the course of antibiotics prematurely.
Consequences of Misuse: Leads to the development of antibiotic resistance in bacteria, making infections harder to treat in the future. Can also cause nausea, stomach ache, dysentery, and vomiting.
Generic Medicines
Definition: Generic medicines are produced and distributed without patent. They are equivalent to branded medicines in terms of dosage, safety, strength, route of administration, quality, performance, and intended use. Their manufacturing cost is less due to no research expenses, hence they are cheaper.
Benefits: More affordable, making healthcare accessible to a wider population.
Lifestyle and Diseases
Lifestyle plays a significant role in preventing or causing diseases. A healthy lifestyle includes:
- Balanced diet.
- Adequate sleep (7-8 hours).
- Regular physical exercise (e.g., walking, jogging, cycling, yoga).
- Avoiding addictions (tobacco, alcohol, drugs).
- Managing stress.
- Proper hygiene and sanitation.
Adopting a healthy lifestyle can significantly reduce the risk of non-infectious diseases like diabetes, heart disease, and cancer, and also strengthen the immune system against infectious diseases.
Blood Donation
Importance: Donating blood is a selfless act that can save lives. Blood is essential for patients undergoing surgery, accident victims, cancer patients, and those with blood disorders.
Eligibility: Healthy individuals between 18 and 60 years of age, weighing more than 50 kg, can donate blood. A person can donate blood 3-4 times a year.
Benefits: Donating blood helps maintain blood circulation, and the body produces new blood, which is beneficial for the donor's health.
Organ Donation
Importance: Organ donation is the process of donating organs (like kidneys, heart, liver, lungs, pancreas, eyes, skin, etc.) after death to save or improve the lives of others. It is a critical medical procedure for patients with end-stage organ failure.
Process: Individuals can pledge to donate their organs by signing a donor card. The decision is usually confirmed with family consent after death.
Benefits: Organ donation gives a second chance at life to recipients, significantly improving their quality of life and extending their lifespan.
Summary
- Health is a state of complete physical, mental, and social well-being. Disease is a disturbance in normal body functioning.
- Diseases are classified as infectious (spread by pathogens) and non-infectious (due to internal factors/lifestyle).
- Common infectious diseases include TB, Hepatitis, Dysentery, Typhoid, Cholera, Malaria, Dengue, Swine Flu, AIDS, and Rabies, each with specific pathogens, modes of infection, symptoms, and prevention.
- Non-infectious diseases like Cancer, Diabetes, and Heart Diseases are often linked to lifestyle, genetics, and stress.
- Misuse of antibiotics leads to drug resistance. Generic medicines are affordable alternatives.
- A healthy lifestyle (balanced diet, exercise, good sleep, no addictions) is crucial for disease prevention.
- Blood and organ donation are vital acts that save lives and improve public health.
References
- Maharashtra State Board Science and Technology Standard Eight Textbook (Specific Edition/Year) - Chapter 2: Health and Diseases.
- Maharashtra State Board 8th Standard Science Syllabus.
- Balbharati Science and Technology Textbook.