1. Health vs disease
| Feature | Health | Disease |
|---|---|---|
| Meaning | State of complete physical, mental and social well-being. | Condition that impairs normal functioning of the body or mind. |
| Influences | Balanced diet, hygiene, exercise, mental peace and social environment. | Pathogens, genetic abnormalities, lifestyle, environment and social conditions. |
| Example of prevention | Personal and public hygiene, vaccination and healthy habits. | Early diagnosis, appropriate treatment and control of transmission. |
2. Bacterial vs viral vs protozoan vs helminthic diseases
| Category | Disease / pathogen | Transmission | Key symptom / point |
|---|---|---|---|
| Bacterial | Typhoid - Salmonella typhi; pneumonia - Streptococcus pneumoniae / Haemophilus influenzae | Contaminated food/water; droplets | Typhoid: sustained high fever; pneumonia: fluid-filled alveoli and breathing difficulty. |
| Viral | Common cold - rhinoviruses | Droplets and contaminated objects | Nasal congestion, sore throat, cough and headache; affects nose and respiratory passage, not lungs. |
| Protozoan | Malaria - Plasmodium; amoebiasis - Entamoeba histolytica | Female Anopheles mosquito; contaminated food/water and houseflies | Malaria fever recurs with release of haemozoin; amoebiasis causes mucus/blood in stool. |
| Helminthic | Ascariasis - Ascaris; filariasis - Wuchereria | Contaminated food/water; mosquito vectors | Ascaris affects intestine; filaria affects lymph vessels and causes elephantiasis. |
3. Innate immunity vs acquired immunity
| Feature | Innate immunity | Acquired immunity |
|---|---|---|
| Present from | Birth | After exposure to specific antigen or vaccination |
| Specificity | Non-specific | Pathogen / antigen specific |
| Response on repeat exposure | No immunological memory | Secondary response is faster and stronger due to memory cells |
| Components | Physical, physiological, cellular and cytokine barriers | B-lymphocytes, T-lymphocytes and antibodies / cell-mediated response |
4. Active vs passive immunity
| Feature | Active immunity | Passive immunity |
|---|---|---|
| Source | Body produces its own antibodies after antigen exposure. | Ready-made antibodies are received. |
| Onset | Slow; develops after a lag period | Immediate |
| Duration / memory | Long-lasting; memory cells form | Temporary; no memory cells form |
| Examples | Natural infection or vaccination | Maternal antibodies through placenta/colostrum; antivenom injection |
5. Humoral vs cell-mediated immune response
| Point | Humoral response | Cell-mediated response |
|---|---|---|
| Main cells | B-lymphocytes | T-lymphocytes |
| Effector | Antibodies in body fluids | Activated T cells |
| Best known role | Neutralises antigens in fluids | Rejects transplanted tissue and attacks infected/abnormal cells |
| Basis for | Vaccination and antibody-mediated defence | Graft rejection |
6. HIV infection vs AIDS
| Feature | HIV infection | AIDS |
|---|---|---|
| Meaning | Infection with Human Immunodeficiency Virus, a retrovirus. | Advanced syndrome caused by severe immune suppression due to HIV. |
| Main target | Macrophages and helper T lymphocytes | Marked fall in helper T-cell count enables opportunistic infections. |
| Transmission | Sexual contact, contaminated blood/needles, infected mother to child. | Not spread by casual contact, sharing food, mosquito bites or social interaction. |
| Detection | ELISA detects antibodies; confirmatory testing is used. | Clinical picture includes recurrent infections and progressive immune failure. |
7. Benign vs malignant tumour
| Feature | Benign tumour | Malignant tumour |
|---|---|---|
| Growth | Remains confined to original location | Invades surrounding tissues |
| Spread | Does not spread to distant sites | Can spread through blood to new sites - metastasis |
| Risk | Usually less harmful unless it compresses vital structures | Potentially life-threatening |
| Control failure | Abnormal growth but usually localised | Loss of normal contact inhibition and uncontrolled proliferation |
8. Drug classes and common effects
| Class | Examples | Source / action |
|---|---|---|
| Opioids | Morphine, heroin (smack) | Poppy latex / derivatives; bind opioid receptors in CNS and gastrointestinal tract. |
| Cannabinoids | Marijuana, hashish, ganja | Cannabis sativa; affect cardiovascular system and CNS. |
| Coca alkaloid | Cocaine (coke / crack) | Erythroxylum coca; interferes with dopamine transport and causes euphoria. |
| Hallucinogens | LSD | Produces altered perception and hallucinations. |