🌸Chapter 7
Human Health and Diseases
(Summary Notes)
🧬 1. HEALTH
- Definition (NCERT keyword):
A state of complete physical, mental, and social well-being and not merely the absence of disease. - Factors affecting health:
• Diet
• Hygiene
• Environment
• Genetic factors
• Lifestyle
🦠 2. DISEASE
- Definition:
Any deviation from normal functioning of body organs or systems. - Types:
1.
Infectious
(Communicable):
Caused by pathogens; e.g., Typhoid, Malaria, AIDS
2.
Non-infectious
(Non-communicable):
Genetic, lifestyle, or deficiency diseases; e.g., Cancer, Diabetes
⚔️ 3. PATHOGENS
Organisms causing diseases.
Major groups:
|
Type |
Example |
Disease |
|
Bacteria |
Salmonella typhi |
Typhoid |
|
Virus |
HIV |
AIDS |
|
Protozoa |
Plasmodium |
Malaria |
|
Fungi |
Microsporum |
Ringworm |
|
Helminth |
Wuchereria bancrofti |
Filariasis |
💉 4. COMMON DISEASES IN
HUMANS
🧪 (A) BACTERIAL DISEASES
|
Disease |
Causative Agent |
Symptoms |
Transmission |
|
Typhoid |
Salmonella typhi |
High fever, weakness, intestinal perforation |
Contaminated food/water |
|
Pneumonia |
Streptococcus pneumoniae, Haemophilus influenzae |
Fever, chills, cough |
Droplet infection |
Test:
Widal test (Typhoid)
🦟 (B) PROTOZOAN DISEASE
Malaria:
Plasmodium vivax, P. falciparum
Vector: Female Anopheles mosquito
Life cycle diagram (for revision):
Human (Asexual phase)
↓
Mosquito bite → sporozoites → liver
→ merozoites → RBCs → gametocytes
↓
Mosquito (Sexual phase)
Gametes → zygote → ookinete → oocyst
→ sporozoites (salivary glands)
🩸 Fever occurs when infected RBCs rupture and
release toxins.
🧬 (C) HELMINTHIC DISEASE
Filariasis (Elephantiasis):
- Wuchereria bancrofti / W.
malayi
- Vector: Female Culex
mosquito
- Symptoms: Swelling of limbs, scrotum.
🍄 (D) FUNGAL DISEASE
Ringworm: Microsporum, Trichophyton, Epidermophyton
- Spread by contact with infected
person or articles.
- Causes itchy circular patches.
🦠 (E) VIRAL DISEASE
AIDS (Acquired Immuno Deficiency Syndrome)
- Causative agent: HIV (Human Immunodeficiency
Virus)
- Transmission:
- Sexual contact
- Contaminated needles
- Blood transfusion
- Mother to child
Effect:
- HIV attacks Helper T-cells
(CD4+ cells) → immune system weakens → opportunistic infections.
Diagnostic test: ELISA
🩸 5. IMMUNITY
Definition:
Ability of the body to resist or fight infection.
Types:
(1) Innate Immunity (Non-specific,
present from birth)
Barriers:
|
Type |
Example |
|
Physical |
Skin, mucous membrane |
|
Physiological |
HCl, tears, saliva |
|
Cellular |
Phagocytes, NK cells |
|
Cytokine |
Interferons (against viruses) |
(2) Acquired Immunity (Specific,
develops after exposure)
- Active: Produced by own body (e.g.,
infection or vaccination).
- Passive: Ready-made antibodies (e.g.,
colostrum, serum therapy).
Diagram: Innate vs Acquired Immunity
IMMUNITY
├── Innate (born with)
│
├── Physical
│
├── Physiological
│
├── Cellular
│
└── Cytokine
└── Acquired (after exposure)
├── Active (infection/vaccine)
└── Passive (mother's milk/serum)
🧫 6. IMMUNE SYSTEM
COMPONENTS
- Lymphoid Organs: Thymus, bone marrow, spleen,
lymph nodes, tonsils.
- Cells:
- B-lymphocytes → produce antibodies
- T-lymphocytes → kill infected
cells (cell-mediated immunity)
💉 7. VACCINATION &
IMMUNISATION
Vaccination: Giving dead/attenuated pathogens to induce immunity.
Immunisation: Process of developing immunity after vaccination.
|
Vaccine |
Disease Prevented |
|
BCG |
Tuberculosis |
|
DPT |
Diphtheria, Pertussis, Tetanus |
|
OPV |
Polio |
|
Hepatitis-B |
Hepatitis |
|
MMR |
Measles, Mumps, Rubella |
Principle: Memory cell formation (secondary immune response).
🧠 8. ALLERGIES
Definition: Exaggerated immune response to harmless substances
(allergens).
Mediator: Histamine (released from mast cells).
Examples: Asthma, hay fever, drug allergy.
Treatment: Antihistamines, steroids, desensitization therapy.
🧬 9. AUTOIMMUNE DISEASES
Definition: Immune system attacks body’s own cells.
Examples:
- Rheumatoid arthritis
- Type I diabetes mellitus
- Multiple sclerosis
🎗️ 10. CANCER
Definition: Uncontrolled cell division leading to tumor formation.
Types:
- Benign: Localized, non-spreading.
- Malignant: Spreads (metastasis).
Causes (Carcinogens):
Radiation, chemicals, viruses (oncogenic viruses), genetic mutations.
Treatment:
Surgery, radiation, chemotherapy, immunotherapy.
🚭 11. DRUG AND ALCOHOL ABUSE
Common Abused Substances
|
Type |
Examples |
|
Depressants |
Alcohol, barbiturates |
|
Stimulants |
Cocaine, amphetamines |
|
Hallucinogens |
LSD, marijuana |
Effects:
- Brain damage, liver cirrhosis,
mental depression, addiction.
Prevention:
Awareness, counselling, peer support, rehabilitation.
🧩 12. AIDS – Detailed
Summary Diagram
HIV virus → attacks CD4+ T-cells
↓
Decreased immunity
↓
Opportunistic infections (TB,
pneumonia, diarrhea, cancer)
↓
Death (due to infections)
Prevention:
- Safe sex practices
- Use sterile needles
- Screen blood before transfusion
- Avoid drug abuse
🩺 13. INTERFERONS
Definition: Proteins secreted by virus-infected cells to protect
neighboring cells from viral infection.
Use: Antiviral and anticancer therapy.
🧠 14. IMPORTANT DEFINITIONS
(Quick NCERT Glossary)
|
Term |
Definition |
|
Pathogen |
Disease-causing organism |
|
Antigen |
Substance triggering immune response |
|
Antibody |
Protein produced by B-cells to neutralize antigen |
|
Vaccination |
Process of introducing antigen to develop immunity |
|
Allergen |
Substance causing allergy |
|
Immunity |
Body’s defense ability |
|
Interferon |
Antiviral protein |
|
Carcinogen |
Cancer-causing agent |
|
AIDS |
Acquired Immuno Deficiency Syndrome |
|
Oncogene |
Gene causing cancer |
|
Colostrum |
First milk rich in antibodies |
|
ELISA |
Test for AIDS detection |
📊 15. NCERT HOT TOPIC CHART
(Quick Recap)
|
Concept |
Key Point |
Exam Tip |
|
Immunity |
Innate + Acquired |
Revise barriers & vaccines |
|
Malaria |
Life cycle of Plasmodium |
Diagram important |
|
AIDS |
HIV structure + T-cell attack |
ELISA test |
|
Allergy |
Histamine + Mast cells |
1 marker |
|
Cancer |
Benign vs Malignant |
Causes & therapy |
|
Drugs |
Alcohol & LSD effects |
NEET factual Qs |
🧩 16. IMPORTANT DIAGRAMS TO
REVISE
1.
Life
cycle of Plasmodium
2.
Life
cycle of Wuchereria bancrofti
3.
Structure
of HIV virus
4.
Types
of immunity (Flow chart)
5.
Vaccination
chart (from NCERT)
🧭 17. QUICK REVISION FORMULA
Health = Prevention + Hygiene + Immunity
Disease = Pathogen + Weak Immunity
Control = Vaccination + Awareness + Treatment
🌟 18. EXAM TIPS
✅ Revise NCERT line diagrams and boxes.
✅ Focus on flowcharts (Malaria, AIDS, Immunity).
✅ Practice MCQs on vaccine, immunity, allergy, and diseases.
✅ Memorize causative agents + symptoms + transmission.
✅ NEET Concept Links: Immunity, Vaccination, AIDS, Cancer, Drugs.
