Human Health & Disease: Essential NEET Facts

HIV is a retrovirus carrying reverse transcriptase (RNA → DNA). It targets CD4+ T-helper cells specifically.
HIV diagnosis: ELISA (screening) → Western blot (confirmation).
Malaria vectors: female Anopheles only (P. vivax = 48-hr cycle; P. falciparum = most lethal/malignant tertian).
Haemozoin pigment released during RBC rupture in malaria causes cyclic fever.
Filariasis vector: Culex mosquito (NOT Anopheles) — caused by Wuchereria bancrofti/malayi, affects lymphatics.
Typhoid: Salmonella typhi → small intestine → Widal test.
Pneumonia: Streptococcus pneumoniae + Haemophilus influenzae → fluid-filled alveoli.
Amoebiasis: Entamoeba histolytica → large intestine → bloody diarrhoea.
Ascariasis: Ascaris lumbricoides → intestinal blockage; filariasis → lymphoedema (elephantiasis).
IgA is the antibody in colostrum (first breast milk).
IgG is the antibody that crosses the placenta.
IgE mediates allergic responses via mast cells → histamine release.
Active immunity: self-produced, slow onset, long-lasting, memory cells formed.
Passive immunity: preformed antibodies received, immediate, short-lived, NO memory cells.
Innate immunity has 4 barrier types: physical, physiological, cellular, cytokine.
NK cells are part of innate cellular immunity.
Interferons are cytokine barriers against viral infections.
Cancer: oncogenes (activated proto-oncogenes) promote division; p53 and Rb are tumour suppressors.
Malignant tumours metastasise via blood/lymph; benign are localised.
Heroin = diacetylmorphine from Papaver somniferum (opium poppy); CNS depressant.
Cocaine from Erythroxylum coca; blocks dopamine reuptake; CNS stimulant.
Cannabinoids from Cannabis sativa; affect cardiovascular system.
Nicotine: addictive, carcinogenic → lung cancer, emphysema.
Autoimmunity = immune attack on self-tissue; example: rheumatoid arthritis.
Biopsy is the gold standard for cancer diagnosis.