Interactive lab

Four core activities

Every activity uses real chapter content and keeps your progress in both study modes. Each also appears inside the topic where it helps most.

Centerpiece

Name the target and effector, then the type; then one clue changes and the mechanism switches.

In context: 3.3 Hypersensitivity reactions →

Centerpiece · Hypersensitivity case sorter

Hypersensitivity case sorter

Read the case, then decide where the antigen is and what does the damage. Only then choose the type. After a correct answer, one clue changes: decide again and watch the mechanism move.

Solved 0 of 9

  1. 1. Target + effector
  2. 2. Type
  3. 3. One clue changes
  4. 4. Type again

The case

A 24-year-old woman with a sore throat takes amoxicillin; she had a full course of penicillin two years ago without problems. Within 15 minutes of the first tablet she has generalized hives, wheezing and a blood pressure of 80/50 mm Hg; serum tryptase is raised.

What caused the reaction?

Step 1 · Where is the antigen, and what does the damage?

Target
Effector

Choose one target and one effector, then check.

The worked solution unlocks after your first attempt.
Causal chains

Type I sensitization, immune complex to vasculitis, AIRE and tolerance, HIV entry to opportunistic infection.

In context: 3.3, 3.5, 3.7 →

Core activity · The Missing Arrow

The Missing Arrow

Complete the causal chain. Place the missing step by dragging a card onto a gap, or tap a card and then tap the gap. Some gaps need an event; others need the mechanism that links one event to the next.

A child inhales grass pollen in spring for the first time, and again the next spring. Complete the chain to the itchy wheal on her skin-prick test.

One gap asks for the event that sensitizes the mast cell; another asks for the mechanism that sets it off on re-exposure.

  1. Dendritic cells present pollen peptide to naive CD4 T cells
  3. B cells switch to IgE against pollen
  4. IgE circulates and binds the high-affinity Fc receptor
  8. histamine dilates venules and opens endothelial junctions
  9. Wheal and flare within 15–20 minutes; late-phase eosinophils hours later

Cards

Tap or drag a card. Placing a used card moves it.

Look-alikes

Anti-GBM vs PSGN, hereditary vs allergic angioedema, Bruton vs hyper-IgM.

In context: 3.3, 3.6, 3.7 →

Core activity · Almost Twins

Almost Twins

Two look-alikes side by side. Decide what they share, then pick the clue that separates them and say why it works.

Look-alike A

Anti-GBM (Goodpasture) disease

Linear IgG along the basement membraneLinear: anti-GBM (type II)
Glomerular capillary loop, immunofluorescence for IgG (schematic).
  • Hematuria, red-cell casts, rising creatinine
  • Smooth linear IgG along the basement membrane; antibody against type IV collagen fixed in the GBM
  • Serum C3 usually normal
  • May bleed into the lungs (alveolar basement membrane shares the antigen)

Step 1 · What they share

What do the two diseases share?

Select every feature that both show.

Case reasoning

ANCA or immune complex; bradykinin or histamine; a boy or a girl with no B cells.

In context: 3.3 Necrotizing vasculitis →

Core activity · One Fact Changes

One Fact Changes

Answer a case and name the decisive clue. Then exactly one fact changes. Decide whether the answer moves, and why.

1 · The original case

A 50-year-old man has fever, weight loss, abdominal pain, bloody urine and red-purple palpable skin lesions. Skin biopsy shows fibrinoid necrosis of small arteries with neutrophils. p-ANCA (anti-myeloperoxidase) is strongly positive; immunofluorescence shows almost no immunoglobulin or complement; serum C3 and C4 are normal.

Which mechanism best explains the vasculitis?

Which fact decided it?