Pocket Notes — Human Health and Disease
Pathogens quick recall
| Disease | Pathogen | Class |
|---|---|---|
| Typhoid | Salmonella typhi | Bacterium |
| Pneumonia | Streptococcus pneumoniae / H. influenzae | Bacterium |
| Common cold | Rhinovirus | Virus |
| Dengue | Dengue virus (via Aedes) | Virus |
| Chikungunya | Chikungunya virus (via Aedes) | Virus |
| Malaria | Plasmodium spp. | Protozoan |
| Amoebiasis | Entamoeba histolytica | Protozoan |
| Ringworm | Microsporum, Trichophyton | Fungus |
| Ascariasis | Ascaris | Helminth |
| Elephantiasis (filariasis) | Wuchereria bancrofti / W. malayi (via Culex) | Helminth |
| AIDS | HIV | Retrovirus |
Malaria
- Vector: **female Anopheles**
- Most dangerous species: Plasmodium falciparum
- Toxin causing chill+fever: haemozoin
- Cycle needs both mosquito & humans (mosquito = definitive host; human = intermediate).
Widal test
Diagnoses typhoid — detects antibodies against Salmonella typhi.
Immunity
- Innate — non-specific, present from birth.
- Acquired — specific, develops after exposure.
Barriers of innate immunity: Physical, Physiological, Cellular, Cytokine.
Acquired immunity types
| Type | Component | Where |
|---|---|---|
| Humoral | Antibodies from B cells | Blood |
| Cell-mediated | T cells | Tissues |
- Active — body makes antibodies (infection / vaccine).
- Passive — ready antibodies (colostrum IgA / anti-tetanus serum).
5 antibody classes (mnemonic: GAMED)
G — IgG (most abundant, crosses placenta) · A — IgA (mucosa, colostrum) · M — IgM (first response) · E — IgE (allergies) · D — IgD (B cell receptor)
Antibody structure
Y-shaped, 4 chains — 2 heavy + 2 light = H₂L₂.
Lymphoid organs
| Primary (mature) | Secondary (act) |
|---|---|
| Bone marrow | Spleen |
| Thymus | Lymph nodes, tonsils, MALT, Peyer's patches |
AIDS quick facts
- HIV = retrovirus (RNA + reverse transcriptase).
- Targets helper T cells (CD4).
- Not transmitted by: hugging, sharing food, mosquito bite.
- Diagnosis: ELISA.
- Treatment: anti-retroviral (ART) drugs — controls, does not cure.
Cancer
- Uncontrolled division · Loss of contact inhibition.
- Benign (localised) vs Malignant (invasive + metastasis).
- Proto-oncogene → Oncogene (activation).
- Detection: biopsy, CT, MRI, radioactive antibodies.
- Treatment: surgery + radiotherapy + chemotherapy + immunotherapy (α-interferon).
Common drugs quick recall
| Drug | Source | Effect |
|---|---|---|
| Opioids (heroin/smack) | Papaver somniferum (poppy) | CNS depressant |
| Cannabinoids (marijuana, hashish) | Cannabis sativa | Affect CVS |
| Cocaine (coke, crack) | Erythroxylum coca | Stimulant, dopamine surge |
Allergy essentials
- Trigger: allergens (dust, pollen, mites).
- Mediators released by mast cells: histamine + serotonin.
- Treatment: anti-histamines, steroids, adrenaline.
Vaccines
- Introduce antigens → memory B & T cells form.
- Recombinant Hepatitis B vaccine — antigen made in yeast (Saccharomyces cerevisiae).
Autoimmune example
Rheumatoid arthritis — antibodies attack joints.
FAQ traps
- Which mosquito for dengue? — Aedes (not Anopheles).
- Which for elephantiasis? — Culex.
- What does colostrum give? — Passive immunity via IgA.
- Which antibody is most abundant? — IgG.
- Which crosses placenta? — IgG.