Interactive lab

Six 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

Predict ICF and ECF volume, osmolality and water shift for eleven events, then watch the boxes change.

In context: 4.2 Fluid shifts →

Centerpiece · Fluid Compartment Predictor

Where does the water go?

Pick an event. For the cells (ICF) and the extracellular fluid (ECF), predict whether volume and osmolality rise, fall or stay the same, and which way water crosses the cell membrane. Then reveal.
0/11 solved

Event

A 70-kg man receives 2 L of 0.9% NaCl intravenously over an hour.

+ isotonic NaCl → ECF

Before the event: ICF two-thirds and ECF one-third of body water at normal osmolalityOsmolalityVolumecell membraneICFcells, 2/3ECF1/3Before: predict, then reveal
Dashed: beforeSolid: afterWidth = volume · height = osmolalitySchematic, exaggerated
ICF (cells)

Volume

Osmolality

ECF

Volume

Osmolality

Water across the cell membrane

Make all five predictions, then check. The boxes will change to the real result.

Reasoning workbench

Six guided gases, or enter pH, PaCO₂, HCO₃⁻, Na⁺, Cl⁻ and albumin: name the primary disorder, calculate the expected compensation and the anion gap, and check for a second disorder, with every formula and substitution shown.

In context: 4.4 Acid–base →

Activity · Acid–base workbench

Work the gas, one decision at a time

Primary disorder, then the compensation check with its calculation, then the anion gap, then anything left over. A step opens only when the one before it is right. Use the guided cases, or enter values and do the arithmetic yourself.

Case

A 47-year-old man found collapsed in a pool of vomitus; respirations 30/min; muscle spasms in arms and jaw; oxalate crystals in the urine. Work up answer D of Simulation Q31.

ABG (option D)
pH 7.29 · PaCO₂ 30 mm Hg · HCO₃⁻ 14 mEq/L
Serum
Na⁺ 137 · Cl⁻ 99 · HCO₃⁻ 8 mEq/L
Osmolality
328 mOsm/kg; calculated–measured gap 32
  1. 1. pH
  2. 2. Primary
  3. 3. Compensation
  4. 4. Anion gap
  5. 5. Second disorder?

    Step 1 · pH

    pH 7.29 is:

    Midterm sim. p.12–13
    3D model

    Trace an embolus from the femoral vein through the right heart to the pulmonary arteries, predict each next structure and compare small, large and saddle emboli. Works as a 2D diagram without WebGL.

    In context: 4.6 Thrombosis and embolism →

    Activity · 3D teaching model

    Thrombus to pulmonary embolism: trace the route

    Predict where the clot goes before the model shows you. This is a schematic built from simple shapes to show how the vessels connect: it is not to scale and it is not a scan or a specimen.
    Patient's rightPatient's leftfront viewThrombus (attached)Right femoral vein
    Teaching schematic, front view. The leg is shortened and vessel widths are exaggerated. Blue vessels carry deoxygenated blood (systemic veins and pulmonary arteries); the left heart is shown in grey because it is not on this route.

    The 2D diagram shows the same route, steps and questions as the 3D model.

    Stage 1 of 5

    A mass in the femoral vein

    A 62-year-old man is on bed rest five days after a hip replacement. His right calf and thigh are swollen. The cutaway shows a dark red mass fixed to the wall of the right femoral vein, in the pocket behind a valve cusp.

    The thrombus is attached to the wall of the right femoral vein; nothing has detached yet.

    The mass is attached to the vein wall where it formed. What is it, and which part of the Virchow triad matters most here?

    L4 p.34–36
    Answer the prediction to continue.
    Causal chains

    SIADH, vomiting alkalosis, nephrotic edema, DVT to PE, sepsis: fill the missing step.

    In context: 4.3, 4.4, 4.5, 4.6, 4.7 →

    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 64-year-old smoker with small cell carcinoma of the lung has a seizure. Serum Na⁺ is 116 mEq/L. Complete the chain from the tumor to the seizure.

    Two gaps need a mechanism (how one step causes the next); two need an event (what has happened).

    1. Small cell carcinoma secretes ADH whatever the plasma osmolality
    3. Free water reabsorbed; urine concentrated (UOsm > 100 mOsm/kg)
    4. retained water dilutes the ECF
    7. Brain cells swell inside the skull (cerebral edema)
    8. raised intracranial pressure and neuronal dysfunction

    Cards

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

    Look-alikes

    Six look-alike pairs, from central vs nephrogenic DI to hypovolemic vs cardiogenic shock.

    In context: 4.2, 4.3, 4.5, 4.6, 4.7 →

    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

    Central diabetes insipidus

    Central diabetes insipidus: no ADH reaches a normal collecting-duct cellcollecting ductADHNo ADH; receptor works
    After pituitary surgery: no ADH reaches a normal collecting duct (schematic).
    • Polyuria, polydipsia, dilute urine
    • Plasma osmolality and Na⁺ high-normal or high
    • Urine concentrates after desmopressin
    • Head trauma, pituitary surgery, craniopharyngioma

    Step 1 · What they share

    What do these two patients share?

    Select every feature that both show.

    Case reasoning

    Change one lab value (chloride, PaCO₂, urine osmolality, desmopressin response, hemoglobin) and decide whether the diagnosis moves.

    In context: 4.4 Anion gap →

    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 45-year-old man has had profuse watery diarrhea for five days. Na⁺ 138, Cl⁻ 114, HCO₃⁻ 14 mEq/L. Arterial pH 7.31, PaCO₂ 29 mm Hg.

    What kind of acidosis is this?

    Which fact decided the type?