Immunology & Exam Strategy – Comprehensive Notes

Viruses

• Extremely small: on the order of nanometres (rough reference in class: “something-nanometres; 2 is there, 5 is there”).
• Invisible with standard light microscopes.
• Structural components
  • Nucleic-acid core (DNA or RNA)
  • Protein capsid
  • May possess an additional nuclear envelope (lipid bilayer taken from host)
  • Spikes (surface proteins) used for host-cell attachment & entry.
• Biological nature
  • Obligate intracellular parasites → can only replicate inside living host cells.
  • Term virulent = capable of causing serious disease.
  • Mentioned term pili/pilus (bacterial attachment structure) appeared on ATI dynamic quiz; flagged for review.

ATI Dynamic Quizzing & Study-Strategy

• Access granted ~ 10 weeks into term.
• Dynamic Quizzing
  • Lets students build custom NCLEX-style question sets based on weak areas.
  • Program does not repeat questions → finishing the easy bank forces only difficult items to remain.
• Observed pitfalls
  • Students answering ≈100 questions/day (≈700 wk; >6 000 total) ended up with disproportionately hard graded assessments.
  • Excessive practice drains “easy” pool → assessment = high difficulty only.
• Instructor’s unofficial advice
  • Complete all required ATI homework (doesn’t deplete question bank).
  • Limit extra dynamic quizzes to ≈50 questions/week (or fewer) to preserve balanced difficulty.
  • Seek additional banks (Quizlet, UWorld ≈5 000 Qs) for high-volume practice rather than ATI.
• Grading weight
  • ATI assessments constitute about 20\% of course mark – enough to matter but cannot individually cause course failure (minimum overall pass =75).

Prions & Creutzfeldt–Jakob Disease (CJD)

• Both variant (vCJD) and classic CJD are prion diseases.
  • Misfolded proteins → induce abnormal folding of normal proteins.
• Transmission differences
  • Variant CJD: acquired from bovine spongiform encephalopathy (mad-cow)–contaminated meat.
  • Classic / sporadic CJD: most commonly
  • Iatrogenic → via unsterile neurosurgical instruments or other medical equipment.
  • Also possible via inherited mutations.
• Nursing relevance: strict sterilisation of neurosurgical tools; prions resist standard autoclaving.

Overview of White Blood Cells (WBCs)

• Produced in red bone marrow.
• Three big functional groups
  1. Granulocytes: neutrophils, eosinophils, basophils
  2. Monocytes → macrophages
  3. Lymphocytes: B, T, NK cells
• Quick roles
  • Neutrophils & macrophages: front-line phagocytosis of large particles/pathogens.
  • NK (natural-killer) cells: cytotoxic lymphocytes that destroy virus-infected / tumour cells (adaptive trigger needed).

Granulocyte Cheat-Sheet

• Remember visual cue: cytoplasm looks “grainy” under light microscope.

Eosinophils

• Key facts ("1 fact, 2 things")
  • Allergy (hypersensitivity) mediators.
  • Anti-parasitic, esp. helminth (worm) infections.
• Elevated eosinophil count → think asthma, hay fever, parasitic worms.

Basophils (≈ Mast Cells)

• Release inflammatory mediators
  • Prominent chemical: histamine (vasodilation, ↑vascular permeability → redness, swelling, itch).
  • Also store/release eicosanoids & leukotrienes (Chapter 6 chemistry review).
• Mast cells = tissue-resident counterpart performing similar functions.
• Clinical pearl: Over-active histamine response may be exacerbated by alcohol (hepatically prioritised toxin, adds inflammatory burden).

Neutrophils

• Name hints at function: “neutralise” pathogens via rapid phagocytosis.
• First WBC to arrive at acute infection site; form pus when they die.

Dendritic Cells

• Found in epidermal stratum basale & other tissues (integumentary Ch 6).
• Capture antigens in skin → migrate to lymph nodes to activate adaptive immunity.

Innate vs Adaptive Immunity

• Two canonical classifications – also labelled by multiple synonyms.
  • Innate = nonspecific — present at birth, no memory, immediate.
  • Adaptive = acquired = specific — develops after exposure; slower start, has memory.
• Cell mapping
  • Innate: physical barriers (skin, mucous), neutrophils, macrophages, eosinophils, basophils/mast, dendritic cells, NK, complement, interferon.
  • Adaptive: B-cells (→plasma cells producing antibodies), T-cells (helper & cytotoxic), NK (when specifically primed).

Lines of Defence Framework

1. First Line (Innate)
   • Physical & chemical barriers: skin (largest mucous membrane / cutaneous membrane), sebum, mucus, cilia, normal flora.
2. Second Line (Innate internal)
   • Cellular: phagocytes (neutrophils, macrophages, dendritic), eosinophils, basophils
   • Chemical: interferons (viral replication blocker), complement, acute-phase proteins.
3. Third Line (Adaptive)
   • B-lymphocytes → plasma cells → antibodies (immunoglobulins).
4. Often grouped within “third” – T-lymphocytes (helper CD4⁺, cytotoxic CD8⁺) orchestrate & directly kill.

Cytokines & Interferon

• Cytokines = small proteins that regulate immune activity (signalling molecules).
• Possess short half-lives → effects are rapid & transient t_{1/2}\text{ small} \Rightarrow \text{short-lived action}.
• Interferon (IFN-α/β/γ)
  • Innate antiviral cytokine: induces neighbouring cells to express antiviral proteins → interferes with viral replication cycle.

Antigen vs Antibody (Key NCLEX Pair)

• Antigen: any molecule recognised as foreign; evokes immune response.
• Antibody = Immunoglobulin (Ig)
  • Y-shaped protein produced by plasma cells; binds antigen, tags for destruction.

Five Antibody Classes ("GAMED")

• IgG,\ IgA,\ IgM,\ IgE,\ IgD
• Mnemonic: “I Gained” or “GAMED”.
  • IgE correlates with allergy & parasites (ties back to eosinophils).

Structural Labels to Memorise

• Light Chain (smaller polypeptide)
• Heavy Chain (larger polypeptide)
• Variable Region (tips) → defines antigen specificity; differs among classes.
• Constant Region → conserved backbone; defines class functions.
• Antigen-binding site = top of each “Y” arm.
• Chains held together by disulphide (S–S) bonds.

Miscellaneous Numerical & Practical Facts

• Air embolism ≤20\ \text{mL (cc)} usually dissipates safely (gas dissolves, phagocytes help process).^*
• High-volume caffeine & alcohol each carry distinct systemic effects; alcohol competes for hepatic metabolism, increasing circulating drug levels.

Ethical / Practical Implications

• Over-reliance on single commercial question bank may skew assessment outcomes; balance preparatory sources to maintain equity.
• Strict sterilisation protocols for neurosurgical instruments critical to prevent iatrogenic prion transmission.
• Patient counselling: alcohol avoidance in chronic inflammatory or histamine-sensitive conditions.

Exam & Study Tips

• Know definitions verbatim: “virulent”, “obligate intracellular parasite”, “cytokine”.
• Map each WBC to its signature action (allergy, histamine, phagocytosis, parasites).
• Reproduce antibody diagram from memory with labelled parts and functions.
• Distinguish innate vs adaptive on multiple overlapping classification schemes (cells, timing, specificity, line of defence).
• Practise ATI dynamic quizzes in moderation (≈50 Q/week) & supplement with external banks (UWorld).
• Recall vCJD vs classic CJD sources for infection-control scenarios.

^Note: Numbers are illustrative; always confirm institutional protocols for air-embolism thresholds.