Introduction

Human health and diseases are important topics in NEET Biology, often tested in both theory and application-based MCQs. This chapter explains diseases, immunity, vaccines, antibiotics, and prevention strategies.

Health is physical, mental, and social well-being, not just the absence of disease. Diseases are broadly classified into infectious and non-infectious types.

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1. Types of Diseases

A. Infectious (Communicable) Diseases:

• Caused by pathogens (bacteria, viruses, fungi, protozoa, helminths)

• Spread through air, water, food, vectors, or direct contact

Examples:

B. Non-Infectious (Non-Communicable) Diseases:

• Not caused by pathogens

• Often due to lifestyle, genetics, or environment

Examples:

2. Immunity

Definition:

• Body’s ability to resist infection

Types of Immunity:

A. Innate (Natural) Immunity:

• Present from birth

• Non-specific → Responds immediately

• Components: Skin, mucous membranes, phagocytes, NK cells

B. Acquired (Adaptive) Immunity:

• Develops after exposure to pathogens

• Specific → Memory response

• Types:

  1. Active immunity → Body produces antibodies

     • Natural → Infection

     • Artificial → Vaccination

  2. Passive immunity → Antibodies received externally

     • Natural → Mother to child via placenta/milk

     • Artificial → Injection of antibodies (e.g., antivenom)

NEET Tip:

• Vaccines → Active immunity, long-lasting

• Antisera → Passive immunity, short-term

3. Vaccination

Definition:

• Administration of antigenic material to stimulate immunity

Types of Vaccines:

• Live attenuated → Weakened pathogen (e.g., Measles)

• Killed/inactivated → Dead pathogen (e.g., Polio – Salk vaccine)

• Subunit → Part of pathogen (e.g., Hepatitis B)

• Toxoid → Inactivated toxin (e.g., Tetanus)

NEET Tip:

• Know vaccines for polio, TB, measles, hepatitis, tetanus

4. Antibiotics and Chemotherapy

Antibiotics:

• Substances produced by microorganisms → Kill/inhibit bacteria

• Example: Penicillin → Inhibits bacterial cell wall synthesis

Chemotherapy:

• Use of chemicals to treat infectious or non-infectious diseases

• Example: Antiviral drugs, anticancer drugs

NEET Tip:

• Antibiotics → Only effective against bacteria, not viruses

5. Lifestyle and Preventive Measures

Lifestyle Diseases:

• Obesity, diabetes, hypertension, cardiovascular disorders

• Prevention → Healthy diet, exercise, avoid smoking/alcohol

Preventive Measures for Infectious Diseases:

• Personal hygiene → Hand washing, clean water

• Vector control → Mosquito nets, insecticides

• Quarantine → Stop epidemic spread

NEET Tip:

• Prevention is key → Often asked in NEET MCQs

6. Cancer – Types and Causes

Definition:

• Uncontrolled cell division due to genetic mutation

Types:

• Carcinoma → Epithelial tissue

• Sarcoma → Connective tissue

• Leukemia → Blood cells

• Lymphoma → Lymphatic tissue

Causes:

• Genetic mutation, carcinogens, radiation, viruses (HPV, EBV)

NEET Tip:

• Focus on cancer-causing agents and prevention

7. NEET Important Formulas / Memory Aids

1. Infection Formula: Pathogen + Host → Disease

2. Active immunity formula: Vaccine → Body → Antibodies → Memory cells

3. Passive immunity formula: Antibody injection → Immediate protection

4. Vector-borne disease formula: Pathogen + Vector → Host infection

Mnemonic for Preventive Measures:
“Clean hands, safe food, vaccinated kids, vector control”

8. NEET Exam Tips

• Focus on infectious vs non-infectious diseases

• Memorize causative agents, transmission, symptoms, and vaccines

• Diagram-based questions → Immune response, antibody structure, vaccine mechanism

• Lifestyle disease questions → Prevention and management

Conclusion

Human Health and Diseases are high-yield NEET topics. Mastery of infectious & non-infectious diseases, immunity, vaccines, antibiotics, lifestyle disorders, and prevention is essential for scoring in NEET MCQs and diagram-based questions.

With this StudentBro.in guide, students can efficiently revise disease types, immunity formulas, and preventive strategies, enhancing accuracy and speed during NEET exams.

Remember: Maintaining health = Disease prevention + Immunity + Lifestyle management + Vaccination.