Chain of infection notes
Tue, Nov 10, 2026 · Week 12 · Principles of Biomedical Technology (Principles of Biomedical Science)
Today's goal: Students take notes on the chain of infection, pathogens, and the immune response, then complete the PLTW online task.
This is a model of the work you should turn in today. Use it to check your own: match the structure and the level of detail, do not copy it. Your data and wording should be your own.
Chain of infection (six links, in order):
- Infectious agent: the pathogen itself, for example MRSA bacteria.
- Reservoir: where the agent lives and multiplies, for example a colonized patient or a contaminated surface.
- Portal of exit: how it leaves the reservoir, for example respiratory droplets or wound drainage.
- Mode of transmission: how it travels, for example contact, droplet, or airborne.
- Portal of entry: how it gets into the next host, for example a surgical incision or the respiratory tract.
- Susceptible host: a person who can be infected, for example a patient with a weakened immune system.
Where controls break the chain:
- Hand hygiene breaks the mode of transmission link by removing pathogens before they travel from one person to the next.
- Gloves and gowns (PPE) block the portal of exit and portal of entry by putting a barrier between the agent and the host.
- Aseptic technique during a procedure protects the portal of entry so the agent cannot reach a sterile site.
Immune response outline:
- Innate immunity acts immediately and is non-specific: skin, mucus, inflammation, and white blood cells that engulf invaders.
- Adaptive immunity is slower but specific: B cells make antibodies and memory cells form, so the next exposure is met faster.
Key idea: you only have to break one link to stop the spread, so pick the link a control actually reaches.
| Chain link | Control that breaks it | How it works |
|---|---|---|
| Mode of transmission | Hand hygiene | Removes pathogens before they travel between people |
| Portal of exit and entry | Gloves and gown (PPE) | Barrier between the agent and the host |
| Portal of entry | Aseptic technique | Keeps a sterile site free of the agent during a procedure |
This model shows the level of evidence and organization needed to complete: Completes the infection-control note-taking task: a labeled six-link chain of infection with PPE and aseptic technique mapped to specific links, plus a short innate versus adaptive immunity outline.
- Date and label the entry.
- Record the procedure, observation, or design decision clearly.
- End with what the evidence means and the next step.
Keep the structure. Replace the question, facts, measurements, and evidence. Then recheck units, vocabulary, and whether the conclusion goes beyond the evidence.
Also due today: Complete the assigned PLTW online activity on hospital-acquired infections, then keep these notes in your notebook for Wednesday's case.
Claim ceiling: Today's evidence supports a classroom claim about chain of infection notes. It cannot prove causation, diagnose a real patient, or justify action outside this room.
One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.
Tap an answer to see the full explanation. Nothing is recorded or graded.
It builds this reusable test skill: Matching an infection-control measure to the chain-of-infection link it interrupts.
- Name the concept or data pattern being tested.
- Cross out choices that violate that rule or the evidence.
- Justify the best remaining choice before checking the answer.