Biology · ZoologyZOO 08
Human Health & Disease
Innate and adaptive immunity, vaccines, cancer biology, AIDS, drug and alcohol abuse
Concept Core
Essential theory — everything NCERT tests on Human Health & Disease
IMMUNITY
Innate (non-specific): physical barriers (skin, mucus), cellular barriers (neutrophils, NK cells, macrophages), physiological barriers (HCl, lysozyme), inflammatory response.
Adaptive (specific): Humoral (B-cells, antibodies) + Cell-mediated (T-cells). Primary response: slow, low titre. Secondary response: fast, high titre (memory cells).
ANTIBODIES & VACCINES
Antibody structure: Y-shaped, 4 polypeptides (2 heavy + 2 light chains). 5 types: IgG (most abundant), IgM (first in primary), IgA (secretions), IgE (allergies), IgD (B-cell surface).
Active immunity: antigen → body makes antibodies (vaccines, natural infection). Passive immunity: ready-made antibodies given (antivenom, colostrum). Faster but short-lived.
HIV/AIDS
HIV: Human Immunodeficiency Virus (retrovirus, ssRNA). Attacks helper T-cells (CD4⁺) → immune suppression.
Transmission: sexual contact, infected blood/needles, mother-to-child (breast milk). NOT by casual contact.
Stages: 2–10 yr latent period. AIDS = advanced stage (CD4 count <200). Diagnosed by ELISA, Western blot.
CANCER
Oncogenes: genes that cause cancer (proto-oncogenes activated by mutation/viral). Tumour suppressor genes (e.g., p53, Rb) normally inhibit cell division.
Types: Benign (localised, non-invasive) vs Malignant (invasive, metastatic). Carcinogens: chemical, radiation, viral.
Diagnosis: biopsy, CT, MRI, antibody detection. Treatment: surgery, radiation, chemotherapy.
DRUGS & ALCOHOL ABUSE
Opioids: heroin (diacetylmorphine), morphine — bind opioid receptors, euphoria, highly addictive.
Cannabinoids: THC (from Cannabis sativa), marijuana, hashish, ganja. Acts on cannabinoid receptors in brain.
Coca alkaloids: cocaine from Erythroxylum coca. Stimulant.
Morphine: used medically for pain but addictive. Barbiturates, benzodiazepines: sedatives.
Fact & Formula Vault
High-yield facts, numbers, and formulas
Immunity Types
Innate: non-specific, no memory
Adaptive: specific, has memory
Humoral: B-cells, antibodies
Cell-mediated: T-cells, cytotoxic
Antibody Types
IgG: most abundant, crosses placenta
IgM: first in primary response
IgA: secretions (saliva, colostrum)
IgE: allergies (mast cells)
HIV Facts
Retrovirus: RNA → DNA (reverse transcriptase)
Attacks CD4⁺ helper T-cells
Latent period: 2–10 years
Diagnosis: ELISA, Western blot
Worked Examples
NEET-style questions solved step-by-step
EASYPassive immunity is provided by:▾
Passive immunity is provided by:
Ready-made antibodies given from outside the body. Examples: antivenom (snake bite), colostrum (mother's first milk to newborn), immunoglobulin injections. Fast-acting but short-lived (no memory).
MEDIUMHIV attacks which specific cells?▾
HIV attacks which specific cells?
CD4⁺ helper T-lymphocytes (T-helper cells). HIV uses CD4 as receptor. Progressive depletion of these cells leads to immunodeficiency → opportunistic infections → AIDS.
HARDWhich of these is NOT a characteristic of malignant tumours?▾
Which of these is NOT a characteristic of malignant tumours?
Malignant tumours: invasive, metastatic (spread via blood/lymph), poorly defined borders. Benign tumours: localised, encapsulated, non-metastatic. If the option says 'non-metastatic' that describes benign, NOT malignant.
Mistake DNA
Common NEET traps for this chapter
⚠ Active vs Passive immunity
Active immunity is long-lasting (memory cells). Passive is immediate but short-lived (no memory).
✓ Fix: Vaccine = active. Antivenom = passive. 'Active effort' by your body = active immunity.
⚠ HIV transmission
HIV is NOT transmitted by handshakes, sharing food, mosquito bites, or casual contact. Only via blood, sexual contact, breast milk.
✓ Fix: HIV = bodily fluid transmission only
⚠ Benign vs Malignant
Benign does NOT metastasise (spread). Malignant does. Malignant tumours invade surrounding tissue.
✓ Fix: Benign = stays put. Malignant = spreads (metastasis).
Chapter Intelligence
Exam data and last-minute strategy
NEET Frequency
2–3 Q/year. HIV (CD4⁺, ELISA diagnosis), active vs passive immunity, IgG/IgM roles, cancer types (benign vs malignant), drug-source plant names.
High-Yield
IgG = most abundant. IgM = first in primary response. HIV = retrovirus → CD4⁺ T-cells. Benign = localised. Malignant = metastatic. Heroin = diacetylmorphine.
Strategy
Immunity table (innate vs adaptive vs humoral vs cell-mediated). Know antibody types by memory trick: G-Most, M-First, A-Secretion, E-Allergy.
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